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linux/arch/parisc/math-emu/fmpyfadd.c
Linus Torvalds 1da177e4c3 Linux-2.6.12-rc2 
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!
2005-04-16 15:20:36 -07:00

2656 lines
78 KiB
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/*
* Linux/PA-RISC Project (http://www.parisc-linux.org/)
*
* Floating-point emulation code
* Copyright (C) 2001 Hewlett-Packard (Paul Bame) <bame@debian.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/*
* BEGIN_DESC
*
* File:
* @(#) pa/spmath/fmpyfadd.c $Revision: 1.1 $
*
* Purpose:
* Double Floating-point Multiply Fused Add
* Double Floating-point Multiply Negate Fused Add
* Single Floating-point Multiply Fused Add
* Single Floating-point Multiply Negate Fused Add
*
* External Interfaces:
* dbl_fmpyfadd(src1ptr,src2ptr,src3ptr,status,dstptr)
* dbl_fmpynfadd(src1ptr,src2ptr,src3ptr,status,dstptr)
* sgl_fmpyfadd(src1ptr,src2ptr,src3ptr,status,dstptr)
* sgl_fmpynfadd(src1ptr,src2ptr,src3ptr,status,dstptr)
*
* Internal Interfaces:
*
* Theory:
* <<please update with a overview of the operation of this file>>
*
* END_DESC
*/
#include "float.h"
#include "sgl_float.h"
#include "dbl_float.h"
/*
* Double Floating-point Multiply Fused Add
*/
int
dbl_fmpyfadd(
dbl_floating_point *src1ptr,
dbl_floating_point *src2ptr,
dbl_floating_point *src3ptr,
unsigned int *status,
dbl_floating_point *dstptr)
{
unsigned int opnd1p1, opnd1p2, opnd2p1, opnd2p2, opnd3p1, opnd3p2;
register unsigned int tmpresp1, tmpresp2, tmpresp3, tmpresp4;
unsigned int rightp1, rightp2, rightp3, rightp4;
unsigned int resultp1, resultp2 = 0, resultp3 = 0, resultp4 = 0;
register int mpy_exponent, add_exponent, count;
boolean inexact = FALSE, is_tiny = FALSE;
unsigned int signlessleft1, signlessright1, save;
register int result_exponent, diff_exponent;
int sign_save, jumpsize;
Dbl_copyfromptr(src1ptr,opnd1p1,opnd1p2);
Dbl_copyfromptr(src2ptr,opnd2p1,opnd2p2);
Dbl_copyfromptr(src3ptr,opnd3p1,opnd3p2);
/*
* set sign bit of result of multiply
*/
if (Dbl_sign(opnd1p1) ^ Dbl_sign(opnd2p1))
Dbl_setnegativezerop1(resultp1);
else Dbl_setzerop1(resultp1);
/*
* Generate multiply exponent
*/
mpy_exponent = Dbl_exponent(opnd1p1) + Dbl_exponent(opnd2p1) - DBL_BIAS;
/*
* check first operand for NaN's or infinity
*/
if (Dbl_isinfinity_exponent(opnd1p1)) {
if (Dbl_iszero_mantissa(opnd1p1,opnd1p2)) {
if (Dbl_isnotnan(opnd2p1,opnd2p2) &&
Dbl_isnotnan(opnd3p1,opnd3p2)) {
if (Dbl_iszero_exponentmantissa(opnd2p1,opnd2p2)) {
/*
* invalid since operands are infinity
* and zero
*/
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
Set_invalidflag();
Dbl_makequietnan(resultp1,resultp2);
Dbl_copytoptr(resultp1,resultp2,dstptr);
return(NOEXCEPTION);
}
/*
* Check third operand for infinity with a
* sign opposite of the multiply result
*/
if (Dbl_isinfinity(opnd3p1,opnd3p2) &&
(Dbl_sign(resultp1) ^ Dbl_sign(opnd3p1))) {
/*
* invalid since attempting a magnitude
* subtraction of infinities
*/
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
Set_invalidflag();
Dbl_makequietnan(resultp1,resultp2);
Dbl_copytoptr(resultp1,resultp2,dstptr);
return(NOEXCEPTION);
}
/*
* return infinity
*/
Dbl_setinfinity_exponentmantissa(resultp1,resultp2);
Dbl_copytoptr(resultp1,resultp2,dstptr);
return(NOEXCEPTION);
}
}
else {
/*
* is NaN; signaling or quiet?
*/
if (Dbl_isone_signaling(opnd1p1)) {
/* trap if INVALIDTRAP enabled */
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
/* make NaN quiet */
Set_invalidflag();
Dbl_set_quiet(opnd1p1);
}
/*
* is second operand a signaling NaN?
*/
else if (Dbl_is_signalingnan(opnd2p1)) {
/* trap if INVALIDTRAP enabled */
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
/* make NaN quiet */
Set_invalidflag();
Dbl_set_quiet(opnd2p1);
Dbl_copytoptr(opnd2p1,opnd2p2,dstptr);
return(NOEXCEPTION);
}
/*
* is third operand a signaling NaN?
*/
else if (Dbl_is_signalingnan(opnd3p1)) {
/* trap if INVALIDTRAP enabled */
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
/* make NaN quiet */
Set_invalidflag();
Dbl_set_quiet(opnd3p1);
Dbl_copytoptr(opnd3p1,opnd3p2,dstptr);
return(NOEXCEPTION);
}
/*
* return quiet NaN
*/
Dbl_copytoptr(opnd1p1,opnd1p2,dstptr);
return(NOEXCEPTION);
}
}
/*
* check second operand for NaN's or infinity
*/
if (Dbl_isinfinity_exponent(opnd2p1)) {
if (Dbl_iszero_mantissa(opnd2p1,opnd2p2)) {
if (Dbl_isnotnan(opnd3p1,opnd3p2)) {
if (Dbl_iszero_exponentmantissa(opnd1p1,opnd1p2)) {
/*
* invalid since multiply operands are
* zero & infinity
*/
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
Set_invalidflag();
Dbl_makequietnan(opnd2p1,opnd2p2);
Dbl_copytoptr(opnd2p1,opnd2p2,dstptr);
return(NOEXCEPTION);
}
/*
* Check third operand for infinity with a
* sign opposite of the multiply result
*/
if (Dbl_isinfinity(opnd3p1,opnd3p2) &&
(Dbl_sign(resultp1) ^ Dbl_sign(opnd3p1))) {
/*
* invalid since attempting a magnitude
* subtraction of infinities
*/
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
Set_invalidflag();
Dbl_makequietnan(resultp1,resultp2);
Dbl_copytoptr(resultp1,resultp2,dstptr);
return(NOEXCEPTION);
}
/*
* return infinity
*/
Dbl_setinfinity_exponentmantissa(resultp1,resultp2);
Dbl_copytoptr(resultp1,resultp2,dstptr);
return(NOEXCEPTION);
}
}
else {
/*
* is NaN; signaling or quiet?
*/
if (Dbl_isone_signaling(opnd2p1)) {
/* trap if INVALIDTRAP enabled */
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
/* make NaN quiet */
Set_invalidflag();
Dbl_set_quiet(opnd2p1);
}
/*
* is third operand a signaling NaN?
*/
else if (Dbl_is_signalingnan(opnd3p1)) {
/* trap if INVALIDTRAP enabled */
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
/* make NaN quiet */
Set_invalidflag();
Dbl_set_quiet(opnd3p1);
Dbl_copytoptr(opnd3p1,opnd3p2,dstptr);
return(NOEXCEPTION);
}
/*
* return quiet NaN
*/
Dbl_copytoptr(opnd2p1,opnd2p2,dstptr);
return(NOEXCEPTION);
}
}
/*
* check third operand for NaN's or infinity
*/
if (Dbl_isinfinity_exponent(opnd3p1)) {
if (Dbl_iszero_mantissa(opnd3p1,opnd3p2)) {
/* return infinity */
Dbl_copytoptr(opnd3p1,opnd3p2,dstptr);
return(NOEXCEPTION);
} else {
/*
* is NaN; signaling or quiet?
*/
if (Dbl_isone_signaling(opnd3p1)) {
/* trap if INVALIDTRAP enabled */
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
/* make NaN quiet */
Set_invalidflag();
Dbl_set_quiet(opnd3p1);
}
/*
* return quiet NaN
*/
Dbl_copytoptr(opnd3p1,opnd3p2,dstptr);
return(NOEXCEPTION);
}
}
/*
* Generate multiply mantissa
*/
if (Dbl_isnotzero_exponent(opnd1p1)) {
/* set hidden bit */
Dbl_clear_signexponent_set_hidden(opnd1p1);
}
else {
/* check for zero */
if (Dbl_iszero_mantissa(opnd1p1,opnd1p2)) {
/*
* Perform the add opnd3 with zero here.
*/
if (Dbl_iszero_exponentmantissa(opnd3p1,opnd3p2)) {
if (Is_rounding_mode(ROUNDMINUS)) {
Dbl_or_signs(opnd3p1,resultp1);
} else {
Dbl_and_signs(opnd3p1,resultp1);
}
}
/*
* Now let's check for trapped underflow case.
*/
else if (Dbl_iszero_exponent(opnd3p1) &&
Is_underflowtrap_enabled()) {
/* need to normalize results mantissa */
sign_save = Dbl_signextendedsign(opnd3p1);
result_exponent = 0;
Dbl_leftshiftby1(opnd3p1,opnd3p2);
Dbl_normalize(opnd3p1,opnd3p2,result_exponent);
Dbl_set_sign(opnd3p1,/*using*/sign_save);
Dbl_setwrapped_exponent(opnd3p1,result_exponent,
unfl);
Dbl_copytoptr(opnd3p1,opnd3p2,dstptr);
/* inexact = FALSE */
return(OPC_2E_UNDERFLOWEXCEPTION);
}
Dbl_copytoptr(opnd3p1,opnd3p2,dstptr);
return(NOEXCEPTION);
}
/* is denormalized, adjust exponent */
Dbl_clear_signexponent(opnd1p1);
Dbl_leftshiftby1(opnd1p1,opnd1p2);
Dbl_normalize(opnd1p1,opnd1p2,mpy_exponent);
}
/* opnd2 needs to have hidden bit set with msb in hidden bit */
if (Dbl_isnotzero_exponent(opnd2p1)) {
Dbl_clear_signexponent_set_hidden(opnd2p1);
}
else {
/* check for zero */
if (Dbl_iszero_mantissa(opnd2p1,opnd2p2)) {
/*
* Perform the add opnd3 with zero here.
*/
if (Dbl_iszero_exponentmantissa(opnd3p1,opnd3p2)) {
if (Is_rounding_mode(ROUNDMINUS)) {
Dbl_or_signs(opnd3p1,resultp1);
} else {
Dbl_and_signs(opnd3p1,resultp1);
}
}
/*
* Now let's check for trapped underflow case.
*/
else if (Dbl_iszero_exponent(opnd3p1) &&
Is_underflowtrap_enabled()) {
/* need to normalize results mantissa */
sign_save = Dbl_signextendedsign(opnd3p1);
result_exponent = 0;
Dbl_leftshiftby1(opnd3p1,opnd3p2);
Dbl_normalize(opnd3p1,opnd3p2,result_exponent);
Dbl_set_sign(opnd3p1,/*using*/sign_save);
Dbl_setwrapped_exponent(opnd3p1,result_exponent,
unfl);
Dbl_copytoptr(opnd3p1,opnd3p2,dstptr);
/* inexact = FALSE */
return(OPC_2E_UNDERFLOWEXCEPTION);
}
Dbl_copytoptr(opnd3p1,opnd3p2,dstptr);
return(NOEXCEPTION);
}
/* is denormalized; want to normalize */
Dbl_clear_signexponent(opnd2p1);
Dbl_leftshiftby1(opnd2p1,opnd2p2);
Dbl_normalize(opnd2p1,opnd2p2,mpy_exponent);
}
/* Multiply the first two source mantissas together */
/*
* The intermediate result will be kept in tmpres,
* which needs enough room for 106 bits of mantissa,
* so lets call it a Double extended.
*/
Dblext_setzero(tmpresp1,tmpresp2,tmpresp3,tmpresp4);
/*
* Four bits at a time are inspected in each loop, and a
* simple shift and add multiply algorithm is used.
*/
for (count = DBL_P-1; count >= 0; count -= 4) {
Dblext_rightshiftby4(tmpresp1,tmpresp2,tmpresp3,tmpresp4);
if (Dbit28p2(opnd1p2)) {
/* Fourword_add should be an ADD followed by 3 ADDC's */
Fourword_add(tmpresp1, tmpresp2, tmpresp3, tmpresp4,
opnd2p1<<3 | opnd2p2>>29, opnd2p2<<3, 0, 0);
}
if (Dbit29p2(opnd1p2)) {
Fourword_add(tmpresp1, tmpresp2, tmpresp3, tmpresp4,
opnd2p1<<2 | opnd2p2>>30, opnd2p2<<2, 0, 0);
}
if (Dbit30p2(opnd1p2)) {
Fourword_add(tmpresp1, tmpresp2, tmpresp3, tmpresp4,
opnd2p1<<1 | opnd2p2>>31, opnd2p2<<1, 0, 0);
}
if (Dbit31p2(opnd1p2)) {
Fourword_add(tmpresp1, tmpresp2, tmpresp3, tmpresp4,
opnd2p1, opnd2p2, 0, 0);
}
Dbl_rightshiftby4(opnd1p1,opnd1p2);
}
if (Is_dexthiddenoverflow(tmpresp1)) {
/* result mantissa >= 2 (mantissa overflow) */
mpy_exponent++;
Dblext_rightshiftby1(tmpresp1,tmpresp2,tmpresp3,tmpresp4);
}
/*
* Restore the sign of the mpy result which was saved in resultp1.
* The exponent will continue to be kept in mpy_exponent.
*/
Dblext_set_sign(tmpresp1,Dbl_sign(resultp1));
/*
* No rounding is required, since the result of the multiply
* is exact in the extended format.
*/
/*
* Now we are ready to perform the add portion of the operation.
*
* The exponents need to be kept as integers for now, since the
* multiply result might not fit into the exponent field. We
* can't overflow or underflow because of this yet, since the
* add could bring the final result back into range.
*/
add_exponent = Dbl_exponent(opnd3p1);
/*
* Check for denormalized or zero add operand.
*/
if (add_exponent == 0) {
/* check for zero */
if (Dbl_iszero_mantissa(opnd3p1,opnd3p2)) {
/* right is zero */
/* Left can't be zero and must be result.
*
* The final result is now in tmpres and mpy_exponent,
* and needs to be rounded and squeezed back into
* double precision format from double extended.
*/
result_exponent = mpy_exponent;
Dblext_copy(tmpresp1,tmpresp2,tmpresp3,tmpresp4,
resultp1,resultp2,resultp3,resultp4);
sign_save = Dbl_signextendedsign(resultp1);/*save sign*/
goto round;
}
/*
* Neither are zeroes.
* Adjust exponent and normalize add operand.
*/
sign_save = Dbl_signextendedsign(opnd3p1); /* save sign */
Dbl_clear_signexponent(opnd3p1);
Dbl_leftshiftby1(opnd3p1,opnd3p2);
Dbl_normalize(opnd3p1,opnd3p2,add_exponent);
Dbl_set_sign(opnd3p1,sign_save); /* restore sign */
} else {
Dbl_clear_exponent_set_hidden(opnd3p1);
}
/*
* Copy opnd3 to the double extended variable called right.
*/
Dbl_copyto_dblext(opnd3p1,opnd3p2,rightp1,rightp2,rightp3,rightp4);
/*
* A zero "save" helps discover equal operands (for later),
* and is used in swapping operands (if needed).
*/
Dblext_xortointp1(tmpresp1,rightp1,/*to*/save);
/*
* Compare magnitude of operands.
*/
Dblext_copytoint_exponentmantissap1(tmpresp1,signlessleft1);
Dblext_copytoint_exponentmantissap1(rightp1,signlessright1);
if (mpy_exponent < add_exponent || mpy_exponent == add_exponent &&
Dblext_ismagnitudeless(tmpresp2,rightp2,signlessleft1,signlessright1)){
/*
* Set the left operand to the larger one by XOR swap.
* First finish the first word "save".
*/
Dblext_xorfromintp1(save,rightp1,/*to*/rightp1);
Dblext_xorfromintp1(save,tmpresp1,/*to*/tmpresp1);
Dblext_swap_lower(tmpresp2,tmpresp3,tmpresp4,
rightp2,rightp3,rightp4);
/* also setup exponents used in rest of routine */
diff_exponent = add_exponent - mpy_exponent;
result_exponent = add_exponent;
} else {
/* also setup exponents used in rest of routine */
diff_exponent = mpy_exponent - add_exponent;
result_exponent = mpy_exponent;
}
/* Invariant: left is not smaller than right. */
/*
* Special case alignment of operands that would force alignment
* beyond the extent of the extension. A further optimization
* could special case this but only reduces the path length for
* this infrequent case.
*/
if (diff_exponent > DBLEXT_THRESHOLD) {
diff_exponent = DBLEXT_THRESHOLD;
}
/* Align right operand by shifting it to the right */
Dblext_clear_sign(rightp1);
Dblext_right_align(rightp1,rightp2,rightp3,rightp4,
/*shifted by*/diff_exponent);
/* Treat sum and difference of the operands separately. */
if ((int)save < 0) {
/*
* Difference of the two operands. Overflow can occur if the
* multiply overflowed. A borrow can occur out of the hidden
* bit and force a post normalization phase.
*/
Dblext_subtract(tmpresp1,tmpresp2,tmpresp3,tmpresp4,
rightp1,rightp2,rightp3,rightp4,
resultp1,resultp2,resultp3,resultp4);
sign_save = Dbl_signextendedsign(resultp1);
if (Dbl_iszero_hidden(resultp1)) {
/* Handle normalization */
/* A straight foward algorithm would now shift the
* result and extension left until the hidden bit
* becomes one. Not all of the extension bits need
* participate in the shift. Only the two most
* significant bits (round and guard) are needed.
* If only a single shift is needed then the guard
* bit becomes a significant low order bit and the
* extension must participate in the rounding.
* If more than a single shift is needed, then all
* bits to the right of the guard bit are zeros,
* and the guard bit may or may not be zero. */
Dblext_leftshiftby1(resultp1,resultp2,resultp3,
resultp4);
/* Need to check for a zero result. The sign and
* exponent fields have already been zeroed. The more
* efficient test of the full object can be used.
*/
if(Dblext_iszero(resultp1,resultp2,resultp3,resultp4)){
/* Must have been "x-x" or "x+(-x)". */
if (Is_rounding_mode(ROUNDMINUS))
Dbl_setone_sign(resultp1);
Dbl_copytoptr(resultp1,resultp2,dstptr);
return(NOEXCEPTION);
}
result_exponent--;
/* Look to see if normalization is finished. */
if (Dbl_isone_hidden(resultp1)) {
/* No further normalization is needed */
goto round;
}
/* Discover first one bit to determine shift amount.
* Use a modified binary search. We have already
* shifted the result one position right and still
* not found a one so the remainder of the extension
* must be zero and simplifies rounding. */
/* Scan bytes */
while (Dbl_iszero_hiddenhigh7mantissa(resultp1)) {
Dblext_leftshiftby8(resultp1,resultp2,resultp3,resultp4);
result_exponent -= 8;
}
/* Now narrow it down to the nibble */
if (Dbl_iszero_hiddenhigh3mantissa(resultp1)) {
/* The lower nibble contains the
* normalizing one */
Dblext_leftshiftby4(resultp1,resultp2,resultp3,resultp4);
result_exponent -= 4;
}
/* Select case where first bit is set (already
* normalized) otherwise select the proper shift. */
jumpsize = Dbl_hiddenhigh3mantissa(resultp1);
if (jumpsize <= 7) switch(jumpsize) {
case 1:
Dblext_leftshiftby3(resultp1,resultp2,resultp3,
resultp4);
result_exponent -= 3;
break;
case 2:
case 3:
Dblext_leftshiftby2(resultp1,resultp2,resultp3,
resultp4);
result_exponent -= 2;
break;
case 4:
case 5:
case 6:
case 7:
Dblext_leftshiftby1(resultp1,resultp2,resultp3,
resultp4);
result_exponent -= 1;
break;
}
} /* end if (hidden...)... */
/* Fall through and round */
} /* end if (save < 0)... */
else {
/* Add magnitudes */
Dblext_addition(tmpresp1,tmpresp2,tmpresp3,tmpresp4,
rightp1,rightp2,rightp3,rightp4,
/*to*/resultp1,resultp2,resultp3,resultp4);
sign_save = Dbl_signextendedsign(resultp1);
if (Dbl_isone_hiddenoverflow(resultp1)) {
/* Prenormalization required. */
Dblext_arithrightshiftby1(resultp1,resultp2,resultp3,
resultp4);
result_exponent++;
} /* end if hiddenoverflow... */
} /* end else ...add magnitudes... */
/* Round the result. If the extension and lower two words are
* all zeros, then the result is exact. Otherwise round in the
* correct direction. Underflow is possible. If a postnormalization
* is necessary, then the mantissa is all zeros so no shift is needed.
*/
round:
if (result_exponent <= 0 && !Is_underflowtrap_enabled()) {
Dblext_denormalize(resultp1,resultp2,resultp3,resultp4,
result_exponent,is_tiny);
}
Dbl_set_sign(resultp1,/*using*/sign_save);
if (Dblext_isnotzero_mantissap3(resultp3) ||
Dblext_isnotzero_mantissap4(resultp4)) {
inexact = TRUE;
switch(Rounding_mode()) {
case ROUNDNEAREST: /* The default. */
if (Dblext_isone_highp3(resultp3)) {
/* at least 1/2 ulp */
if (Dblext_isnotzero_low31p3(resultp3) ||
Dblext_isnotzero_mantissap4(resultp4) ||
Dblext_isone_lowp2(resultp2)) {
/* either exactly half way and odd or
* more than 1/2ulp */
Dbl_increment(resultp1,resultp2);
}
}
break;
case ROUNDPLUS:
if (Dbl_iszero_sign(resultp1)) {
/* Round up positive results */
Dbl_increment(resultp1,resultp2);
}
break;
case ROUNDMINUS:
if (Dbl_isone_sign(resultp1)) {
/* Round down negative results */
Dbl_increment(resultp1,resultp2);
}
case ROUNDZERO:;
/* truncate is simple */
} /* end switch... */
if (Dbl_isone_hiddenoverflow(resultp1)) result_exponent++;
}
if (result_exponent >= DBL_INFINITY_EXPONENT) {
/* trap if OVERFLOWTRAP enabled */
if (Is_overflowtrap_enabled()) {
/*
* Adjust bias of result
*/
Dbl_setwrapped_exponent(resultp1,result_exponent,ovfl);
Dbl_copytoptr(resultp1,resultp2,dstptr);
if (inexact)
if (Is_inexacttrap_enabled())
return (OPC_2E_OVERFLOWEXCEPTION |
OPC_2E_INEXACTEXCEPTION);
else Set_inexactflag();
return (OPC_2E_OVERFLOWEXCEPTION);
}
inexact = TRUE;
Set_overflowflag();
/* set result to infinity or largest number */
Dbl_setoverflow(resultp1,resultp2);
} else if (result_exponent <= 0) { /* underflow case */
if (Is_underflowtrap_enabled()) {
/*
* Adjust bias of result
*/
Dbl_setwrapped_exponent(resultp1,result_exponent,unfl);
Dbl_copytoptr(resultp1,resultp2,dstptr);
if (inexact)
if (Is_inexacttrap_enabled())
return (OPC_2E_UNDERFLOWEXCEPTION |
OPC_2E_INEXACTEXCEPTION);
else Set_inexactflag();
return(OPC_2E_UNDERFLOWEXCEPTION);
}
else if (inexact && is_tiny) Set_underflowflag();
}
else Dbl_set_exponent(resultp1,result_exponent);
Dbl_copytoptr(resultp1,resultp2,dstptr);
if (inexact)
if (Is_inexacttrap_enabled()) return(OPC_2E_INEXACTEXCEPTION);
else Set_inexactflag();
return(NOEXCEPTION);
}
/*
* Double Floating-point Multiply Negate Fused Add
*/
dbl_fmpynfadd(src1ptr,src2ptr,src3ptr,status,dstptr)
dbl_floating_point *src1ptr, *src2ptr, *src3ptr, *dstptr;
unsigned int *status;
{
unsigned int opnd1p1, opnd1p2, opnd2p1, opnd2p2, opnd3p1, opnd3p2;
register unsigned int tmpresp1, tmpresp2, tmpresp3, tmpresp4;
unsigned int rightp1, rightp2, rightp3, rightp4;
unsigned int resultp1, resultp2 = 0, resultp3 = 0, resultp4 = 0;
register int mpy_exponent, add_exponent, count;
boolean inexact = FALSE, is_tiny = FALSE;
unsigned int signlessleft1, signlessright1, save;
register int result_exponent, diff_exponent;
int sign_save, jumpsize;
Dbl_copyfromptr(src1ptr,opnd1p1,opnd1p2);
Dbl_copyfromptr(src2ptr,opnd2p1,opnd2p2);
Dbl_copyfromptr(src3ptr,opnd3p1,opnd3p2);
/*
* set sign bit of result of multiply
*/
if (Dbl_sign(opnd1p1) ^ Dbl_sign(opnd2p1))
Dbl_setzerop1(resultp1);
else
Dbl_setnegativezerop1(resultp1);
/*
* Generate multiply exponent
*/
mpy_exponent = Dbl_exponent(opnd1p1) + Dbl_exponent(opnd2p1) - DBL_BIAS;
/*
* check first operand for NaN's or infinity
*/
if (Dbl_isinfinity_exponent(opnd1p1)) {
if (Dbl_iszero_mantissa(opnd1p1,opnd1p2)) {
if (Dbl_isnotnan(opnd2p1,opnd2p2) &&
Dbl_isnotnan(opnd3p1,opnd3p2)) {
if (Dbl_iszero_exponentmantissa(opnd2p1,opnd2p2)) {
/*
* invalid since operands are infinity
* and zero
*/
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
Set_invalidflag();
Dbl_makequietnan(resultp1,resultp2);
Dbl_copytoptr(resultp1,resultp2,dstptr);
return(NOEXCEPTION);
}
/*
* Check third operand for infinity with a
* sign opposite of the multiply result
*/
if (Dbl_isinfinity(opnd3p1,opnd3p2) &&
(Dbl_sign(resultp1) ^ Dbl_sign(opnd3p1))) {
/*
* invalid since attempting a magnitude
* subtraction of infinities
*/
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
Set_invalidflag();
Dbl_makequietnan(resultp1,resultp2);
Dbl_copytoptr(resultp1,resultp2,dstptr);
return(NOEXCEPTION);
}
/*
* return infinity
*/
Dbl_setinfinity_exponentmantissa(resultp1,resultp2);
Dbl_copytoptr(resultp1,resultp2,dstptr);
return(NOEXCEPTION);
}
}
else {
/*
* is NaN; signaling or quiet?
*/
if (Dbl_isone_signaling(opnd1p1)) {
/* trap if INVALIDTRAP enabled */
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
/* make NaN quiet */
Set_invalidflag();
Dbl_set_quiet(opnd1p1);
}
/*
* is second operand a signaling NaN?
*/
else if (Dbl_is_signalingnan(opnd2p1)) {
/* trap if INVALIDTRAP enabled */
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
/* make NaN quiet */
Set_invalidflag();
Dbl_set_quiet(opnd2p1);
Dbl_copytoptr(opnd2p1,opnd2p2,dstptr);
return(NOEXCEPTION);
}
/*
* is third operand a signaling NaN?
*/
else if (Dbl_is_signalingnan(opnd3p1)) {
/* trap if INVALIDTRAP enabled */
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
/* make NaN quiet */
Set_invalidflag();
Dbl_set_quiet(opnd3p1);
Dbl_copytoptr(opnd3p1,opnd3p2,dstptr);
return(NOEXCEPTION);
}
/*
* return quiet NaN
*/
Dbl_copytoptr(opnd1p1,opnd1p2,dstptr);
return(NOEXCEPTION);
}
}
/*
* check second operand for NaN's or infinity
*/
if (Dbl_isinfinity_exponent(opnd2p1)) {
if (Dbl_iszero_mantissa(opnd2p1,opnd2p2)) {
if (Dbl_isnotnan(opnd3p1,opnd3p2)) {
if (Dbl_iszero_exponentmantissa(opnd1p1,opnd1p2)) {
/*
* invalid since multiply operands are
* zero & infinity
*/
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
Set_invalidflag();
Dbl_makequietnan(opnd2p1,opnd2p2);
Dbl_copytoptr(opnd2p1,opnd2p2,dstptr);
return(NOEXCEPTION);
}
/*
* Check third operand for infinity with a
* sign opposite of the multiply result
*/
if (Dbl_isinfinity(opnd3p1,opnd3p2) &&
(Dbl_sign(resultp1) ^ Dbl_sign(opnd3p1))) {
/*
* invalid since attempting a magnitude
* subtraction of infinities
*/
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
Set_invalidflag();
Dbl_makequietnan(resultp1,resultp2);
Dbl_copytoptr(resultp1,resultp2,dstptr);
return(NOEXCEPTION);
}
/*
* return infinity
*/
Dbl_setinfinity_exponentmantissa(resultp1,resultp2);
Dbl_copytoptr(resultp1,resultp2,dstptr);
return(NOEXCEPTION);
}
}
else {
/*
* is NaN; signaling or quiet?
*/
if (Dbl_isone_signaling(opnd2p1)) {
/* trap if INVALIDTRAP enabled */
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
/* make NaN quiet */
Set_invalidflag();
Dbl_set_quiet(opnd2p1);
}
/*
* is third operand a signaling NaN?
*/
else if (Dbl_is_signalingnan(opnd3p1)) {
/* trap if INVALIDTRAP enabled */
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
/* make NaN quiet */
Set_invalidflag();
Dbl_set_quiet(opnd3p1);
Dbl_copytoptr(opnd3p1,opnd3p2,dstptr);
return(NOEXCEPTION);
}
/*
* return quiet NaN
*/
Dbl_copytoptr(opnd2p1,opnd2p2,dstptr);
return(NOEXCEPTION);
}
}
/*
* check third operand for NaN's or infinity
*/
if (Dbl_isinfinity_exponent(opnd3p1)) {
if (Dbl_iszero_mantissa(opnd3p1,opnd3p2)) {
/* return infinity */
Dbl_copytoptr(opnd3p1,opnd3p2,dstptr);
return(NOEXCEPTION);
} else {
/*
* is NaN; signaling or quiet?
*/
if (Dbl_isone_signaling(opnd3p1)) {
/* trap if INVALIDTRAP enabled */
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
/* make NaN quiet */
Set_invalidflag();
Dbl_set_quiet(opnd3p1);
}
/*
* return quiet NaN
*/
Dbl_copytoptr(opnd3p1,opnd3p2,dstptr);
return(NOEXCEPTION);
}
}
/*
* Generate multiply mantissa
*/
if (Dbl_isnotzero_exponent(opnd1p1)) {
/* set hidden bit */
Dbl_clear_signexponent_set_hidden(opnd1p1);
}
else {
/* check for zero */
if (Dbl_iszero_mantissa(opnd1p1,opnd1p2)) {
/*
* Perform the add opnd3 with zero here.
*/
if (Dbl_iszero_exponentmantissa(opnd3p1,opnd3p2)) {
if (Is_rounding_mode(ROUNDMINUS)) {
Dbl_or_signs(opnd3p1,resultp1);
} else {
Dbl_and_signs(opnd3p1,resultp1);
}
}
/*
* Now let's check for trapped underflow case.
*/
else if (Dbl_iszero_exponent(opnd3p1) &&
Is_underflowtrap_enabled()) {
/* need to normalize results mantissa */
sign_save = Dbl_signextendedsign(opnd3p1);
result_exponent = 0;
Dbl_leftshiftby1(opnd3p1,opnd3p2);
Dbl_normalize(opnd3p1,opnd3p2,result_exponent);
Dbl_set_sign(opnd3p1,/*using*/sign_save);
Dbl_setwrapped_exponent(opnd3p1,result_exponent,
unfl);
Dbl_copytoptr(opnd3p1,opnd3p2,dstptr);
/* inexact = FALSE */
return(OPC_2E_UNDERFLOWEXCEPTION);
}
Dbl_copytoptr(opnd3p1,opnd3p2,dstptr);
return(NOEXCEPTION);
}
/* is denormalized, adjust exponent */
Dbl_clear_signexponent(opnd1p1);
Dbl_leftshiftby1(opnd1p1,opnd1p2);
Dbl_normalize(opnd1p1,opnd1p2,mpy_exponent);
}
/* opnd2 needs to have hidden bit set with msb in hidden bit */
if (Dbl_isnotzero_exponent(opnd2p1)) {
Dbl_clear_signexponent_set_hidden(opnd2p1);
}
else {
/* check for zero */
if (Dbl_iszero_mantissa(opnd2p1,opnd2p2)) {
/*
* Perform the add opnd3 with zero here.
*/
if (Dbl_iszero_exponentmantissa(opnd3p1,opnd3p2)) {
if (Is_rounding_mode(ROUNDMINUS)) {
Dbl_or_signs(opnd3p1,resultp1);
} else {
Dbl_and_signs(opnd3p1,resultp1);
}
}
/*
* Now let's check for trapped underflow case.
*/
else if (Dbl_iszero_exponent(opnd3p1) &&
Is_underflowtrap_enabled()) {
/* need to normalize results mantissa */
sign_save = Dbl_signextendedsign(opnd3p1);
result_exponent = 0;
Dbl_leftshiftby1(opnd3p1,opnd3p2);
Dbl_normalize(opnd3p1,opnd3p2,result_exponent);
Dbl_set_sign(opnd3p1,/*using*/sign_save);
Dbl_setwrapped_exponent(opnd3p1,result_exponent,
unfl);
Dbl_copytoptr(opnd3p1,opnd3p2,dstptr);
/* inexact = FALSE */
return(OPC_2E_UNDERFLOWEXCEPTION);
}
Dbl_copytoptr(opnd3p1,opnd3p2,dstptr);
return(NOEXCEPTION);
}
/* is denormalized; want to normalize */
Dbl_clear_signexponent(opnd2p1);
Dbl_leftshiftby1(opnd2p1,opnd2p2);
Dbl_normalize(opnd2p1,opnd2p2,mpy_exponent);
}
/* Multiply the first two source mantissas together */
/*
* The intermediate result will be kept in tmpres,
* which needs enough room for 106 bits of mantissa,
* so lets call it a Double extended.
*/
Dblext_setzero(tmpresp1,tmpresp2,tmpresp3,tmpresp4);
/*
* Four bits at a time are inspected in each loop, and a
* simple shift and add multiply algorithm is used.
*/
for (count = DBL_P-1; count >= 0; count -= 4) {
Dblext_rightshiftby4(tmpresp1,tmpresp2,tmpresp3,tmpresp4);
if (Dbit28p2(opnd1p2)) {
/* Fourword_add should be an ADD followed by 3 ADDC's */
Fourword_add(tmpresp1, tmpresp2, tmpresp3, tmpresp4,
opnd2p1<<3 | opnd2p2>>29, opnd2p2<<3, 0, 0);
}
if (Dbit29p2(opnd1p2)) {
Fourword_add(tmpresp1, tmpresp2, tmpresp3, tmpresp4,
opnd2p1<<2 | opnd2p2>>30, opnd2p2<<2, 0, 0);
}
if (Dbit30p2(opnd1p2)) {
Fourword_add(tmpresp1, tmpresp2, tmpresp3, tmpresp4,
opnd2p1<<1 | opnd2p2>>31, opnd2p2<<1, 0, 0);
}
if (Dbit31p2(opnd1p2)) {
Fourword_add(tmpresp1, tmpresp2, tmpresp3, tmpresp4,
opnd2p1, opnd2p2, 0, 0);
}
Dbl_rightshiftby4(opnd1p1,opnd1p2);
}
if (Is_dexthiddenoverflow(tmpresp1)) {
/* result mantissa >= 2 (mantissa overflow) */
mpy_exponent++;
Dblext_rightshiftby1(tmpresp1,tmpresp2,tmpresp3,tmpresp4);
}
/*
* Restore the sign of the mpy result which was saved in resultp1.
* The exponent will continue to be kept in mpy_exponent.
*/
Dblext_set_sign(tmpresp1,Dbl_sign(resultp1));
/*
* No rounding is required, since the result of the multiply
* is exact in the extended format.
*/
/*
* Now we are ready to perform the add portion of the operation.
*
* The exponents need to be kept as integers for now, since the
* multiply result might not fit into the exponent field. We
* can't overflow or underflow because of this yet, since the
* add could bring the final result back into range.
*/
add_exponent = Dbl_exponent(opnd3p1);
/*
* Check for denormalized or zero add operand.
*/
if (add_exponent == 0) {
/* check for zero */
if (Dbl_iszero_mantissa(opnd3p1,opnd3p2)) {
/* right is zero */
/* Left can't be zero and must be result.
*
* The final result is now in tmpres and mpy_exponent,
* and needs to be rounded and squeezed back into
* double precision format from double extended.
*/
result_exponent = mpy_exponent;
Dblext_copy(tmpresp1,tmpresp2,tmpresp3,tmpresp4,
resultp1,resultp2,resultp3,resultp4);
sign_save = Dbl_signextendedsign(resultp1);/*save sign*/
goto round;
}
/*
* Neither are zeroes.
* Adjust exponent and normalize add operand.
*/
sign_save = Dbl_signextendedsign(opnd3p1); /* save sign */
Dbl_clear_signexponent(opnd3p1);
Dbl_leftshiftby1(opnd3p1,opnd3p2);
Dbl_normalize(opnd3p1,opnd3p2,add_exponent);
Dbl_set_sign(opnd3p1,sign_save); /* restore sign */
} else {
Dbl_clear_exponent_set_hidden(opnd3p1);
}
/*
* Copy opnd3 to the double extended variable called right.
*/
Dbl_copyto_dblext(opnd3p1,opnd3p2,rightp1,rightp2,rightp3,rightp4);
/*
* A zero "save" helps discover equal operands (for later),
* and is used in swapping operands (if needed).
*/
Dblext_xortointp1(tmpresp1,rightp1,/*to*/save);
/*
* Compare magnitude of operands.
*/
Dblext_copytoint_exponentmantissap1(tmpresp1,signlessleft1);
Dblext_copytoint_exponentmantissap1(rightp1,signlessright1);
if (mpy_exponent < add_exponent || mpy_exponent == add_exponent &&
Dblext_ismagnitudeless(tmpresp2,rightp2,signlessleft1,signlessright1)){
/*
* Set the left operand to the larger one by XOR swap.
* First finish the first word "save".
*/
Dblext_xorfromintp1(save,rightp1,/*to*/rightp1);
Dblext_xorfromintp1(save,tmpresp1,/*to*/tmpresp1);
Dblext_swap_lower(tmpresp2,tmpresp3,tmpresp4,
rightp2,rightp3,rightp4);
/* also setup exponents used in rest of routine */
diff_exponent = add_exponent - mpy_exponent;
result_exponent = add_exponent;
} else {
/* also setup exponents used in rest of routine */
diff_exponent = mpy_exponent - add_exponent;
result_exponent = mpy_exponent;
}
/* Invariant: left is not smaller than right. */
/*
* Special case alignment of operands that would force alignment
* beyond the extent of the extension. A further optimization
* could special case this but only reduces the path length for
* this infrequent case.
*/
if (diff_exponent > DBLEXT_THRESHOLD) {
diff_exponent = DBLEXT_THRESHOLD;
}
/* Align right operand by shifting it to the right */
Dblext_clear_sign(rightp1);
Dblext_right_align(rightp1,rightp2,rightp3,rightp4,
/*shifted by*/diff_exponent);
/* Treat sum and difference of the operands separately. */
if ((int)save < 0) {
/*
* Difference of the two operands. Overflow can occur if the
* multiply overflowed. A borrow can occur out of the hidden
* bit and force a post normalization phase.
*/
Dblext_subtract(tmpresp1,tmpresp2,tmpresp3,tmpresp4,
rightp1,rightp2,rightp3,rightp4,
resultp1,resultp2,resultp3,resultp4);
sign_save = Dbl_signextendedsign(resultp1);
if (Dbl_iszero_hidden(resultp1)) {
/* Handle normalization */
/* A straight foward algorithm would now shift the
* result and extension left until the hidden bit
* becomes one. Not all of the extension bits need
* participate in the shift. Only the two most
* significant bits (round and guard) are needed.
* If only a single shift is needed then the guard
* bit becomes a significant low order bit and the
* extension must participate in the rounding.
* If more than a single shift is needed, then all
* bits to the right of the guard bit are zeros,
* and the guard bit may or may not be zero. */
Dblext_leftshiftby1(resultp1,resultp2,resultp3,
resultp4);
/* Need to check for a zero result. The sign and
* exponent fields have already been zeroed. The more
* efficient test of the full object can be used.
*/
if (Dblext_iszero(resultp1,resultp2,resultp3,resultp4)) {
/* Must have been "x-x" or "x+(-x)". */
if (Is_rounding_mode(ROUNDMINUS))
Dbl_setone_sign(resultp1);
Dbl_copytoptr(resultp1,resultp2,dstptr);
return(NOEXCEPTION);
}
result_exponent--;
/* Look to see if normalization is finished. */
if (Dbl_isone_hidden(resultp1)) {
/* No further normalization is needed */
goto round;
}
/* Discover first one bit to determine shift amount.
* Use a modified binary search. We have already
* shifted the result one position right and still
* not found a one so the remainder of the extension
* must be zero and simplifies rounding. */
/* Scan bytes */
while (Dbl_iszero_hiddenhigh7mantissa(resultp1)) {
Dblext_leftshiftby8(resultp1,resultp2,resultp3,resultp4);
result_exponent -= 8;
}
/* Now narrow it down to the nibble */
if (Dbl_iszero_hiddenhigh3mantissa(resultp1)) {
/* The lower nibble contains the
* normalizing one */
Dblext_leftshiftby4(resultp1,resultp2,resultp3,resultp4);
result_exponent -= 4;
}
/* Select case where first bit is set (already
* normalized) otherwise select the proper shift. */
jumpsize = Dbl_hiddenhigh3mantissa(resultp1);
if (jumpsize <= 7) switch(jumpsize) {
case 1:
Dblext_leftshiftby3(resultp1,resultp2,resultp3,
resultp4);
result_exponent -= 3;
break;
case 2:
case 3:
Dblext_leftshiftby2(resultp1,resultp2,resultp3,
resultp4);
result_exponent -= 2;
break;
case 4:
case 5:
case 6:
case 7:
Dblext_leftshiftby1(resultp1,resultp2,resultp3,
resultp4);
result_exponent -= 1;
break;
}
} /* end if (hidden...)... */
/* Fall through and round */
} /* end if (save < 0)... */
else {
/* Add magnitudes */
Dblext_addition(tmpresp1,tmpresp2,tmpresp3,tmpresp4,
rightp1,rightp2,rightp3,rightp4,
/*to*/resultp1,resultp2,resultp3,resultp4);
sign_save = Dbl_signextendedsign(resultp1);
if (Dbl_isone_hiddenoverflow(resultp1)) {
/* Prenormalization required. */
Dblext_arithrightshiftby1(resultp1,resultp2,resultp3,
resultp4);
result_exponent++;
} /* end if hiddenoverflow... */
} /* end else ...add magnitudes... */
/* Round the result. If the extension and lower two words are
* all zeros, then the result is exact. Otherwise round in the
* correct direction. Underflow is possible. If a postnormalization
* is necessary, then the mantissa is all zeros so no shift is needed.
*/
round:
if (result_exponent <= 0 && !Is_underflowtrap_enabled()) {
Dblext_denormalize(resultp1,resultp2,resultp3,resultp4,
result_exponent,is_tiny);
}
Dbl_set_sign(resultp1,/*using*/sign_save);
if (Dblext_isnotzero_mantissap3(resultp3) ||
Dblext_isnotzero_mantissap4(resultp4)) {
inexact = TRUE;
switch(Rounding_mode()) {
case ROUNDNEAREST: /* The default. */
if (Dblext_isone_highp3(resultp3)) {
/* at least 1/2 ulp */
if (Dblext_isnotzero_low31p3(resultp3) ||
Dblext_isnotzero_mantissap4(resultp4) ||
Dblext_isone_lowp2(resultp2)) {
/* either exactly half way and odd or
* more than 1/2ulp */
Dbl_increment(resultp1,resultp2);
}
}
break;
case ROUNDPLUS:
if (Dbl_iszero_sign(resultp1)) {
/* Round up positive results */
Dbl_increment(resultp1,resultp2);
}
break;
case ROUNDMINUS:
if (Dbl_isone_sign(resultp1)) {
/* Round down negative results */
Dbl_increment(resultp1,resultp2);
}
case ROUNDZERO:;
/* truncate is simple */
} /* end switch... */
if (Dbl_isone_hiddenoverflow(resultp1)) result_exponent++;
}
if (result_exponent >= DBL_INFINITY_EXPONENT) {
/* Overflow */
if (Is_overflowtrap_enabled()) {
/*
* Adjust bias of result
*/
Dbl_setwrapped_exponent(resultp1,result_exponent,ovfl);
Dbl_copytoptr(resultp1,resultp2,dstptr);
if (inexact)
if (Is_inexacttrap_enabled())
return (OPC_2E_OVERFLOWEXCEPTION |
OPC_2E_INEXACTEXCEPTION);
else Set_inexactflag();
return (OPC_2E_OVERFLOWEXCEPTION);
}
inexact = TRUE;
Set_overflowflag();
Dbl_setoverflow(resultp1,resultp2);
} else if (result_exponent <= 0) { /* underflow case */
if (Is_underflowtrap_enabled()) {
/*
* Adjust bias of result
*/
Dbl_setwrapped_exponent(resultp1,result_exponent,unfl);
Dbl_copytoptr(resultp1,resultp2,dstptr);
if (inexact)
if (Is_inexacttrap_enabled())
return (OPC_2E_UNDERFLOWEXCEPTION |
OPC_2E_INEXACTEXCEPTION);
else Set_inexactflag();
return(OPC_2E_UNDERFLOWEXCEPTION);
}
else if (inexact && is_tiny) Set_underflowflag();
}
else Dbl_set_exponent(resultp1,result_exponent);
Dbl_copytoptr(resultp1,resultp2,dstptr);
if (inexact)
if (Is_inexacttrap_enabled()) return(OPC_2E_INEXACTEXCEPTION);
else Set_inexactflag();
return(NOEXCEPTION);
}
/*
* Single Floating-point Multiply Fused Add
*/
sgl_fmpyfadd(src1ptr,src2ptr,src3ptr,status,dstptr)
sgl_floating_point *src1ptr, *src2ptr, *src3ptr, *dstptr;
unsigned int *status;
{
unsigned int opnd1, opnd2, opnd3;
register unsigned int tmpresp1, tmpresp2;
unsigned int rightp1, rightp2;
unsigned int resultp1, resultp2 = 0;
register int mpy_exponent, add_exponent, count;
boolean inexact = FALSE, is_tiny = FALSE;
unsigned int signlessleft1, signlessright1, save;
register int result_exponent, diff_exponent;
int sign_save, jumpsize;
Sgl_copyfromptr(src1ptr,opnd1);
Sgl_copyfromptr(src2ptr,opnd2);
Sgl_copyfromptr(src3ptr,opnd3);
/*
* set sign bit of result of multiply
*/
if (Sgl_sign(opnd1) ^ Sgl_sign(opnd2))
Sgl_setnegativezero(resultp1);
else Sgl_setzero(resultp1);
/*
* Generate multiply exponent
*/
mpy_exponent = Sgl_exponent(opnd1) + Sgl_exponent(opnd2) - SGL_BIAS;
/*
* check first operand for NaN's or infinity
*/
if (Sgl_isinfinity_exponent(opnd1)) {
if (Sgl_iszero_mantissa(opnd1)) {
if (Sgl_isnotnan(opnd2) && Sgl_isnotnan(opnd3)) {
if (Sgl_iszero_exponentmantissa(opnd2)) {
/*
* invalid since operands are infinity
* and zero
*/
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
Set_invalidflag();
Sgl_makequietnan(resultp1);
Sgl_copytoptr(resultp1,dstptr);
return(NOEXCEPTION);
}
/*
* Check third operand for infinity with a
* sign opposite of the multiply result
*/
if (Sgl_isinfinity(opnd3) &&
(Sgl_sign(resultp1) ^ Sgl_sign(opnd3))) {
/*
* invalid since attempting a magnitude
* subtraction of infinities
*/
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
Set_invalidflag();
Sgl_makequietnan(resultp1);
Sgl_copytoptr(resultp1,dstptr);
return(NOEXCEPTION);
}
/*
* return infinity
*/
Sgl_setinfinity_exponentmantissa(resultp1);
Sgl_copytoptr(resultp1,dstptr);
return(NOEXCEPTION);
}
}
else {
/*
* is NaN; signaling or quiet?
*/
if (Sgl_isone_signaling(opnd1)) {
/* trap if INVALIDTRAP enabled */
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
/* make NaN quiet */
Set_invalidflag();
Sgl_set_quiet(opnd1);
}
/*
* is second operand a signaling NaN?
*/
else if (Sgl_is_signalingnan(opnd2)) {
/* trap if INVALIDTRAP enabled */
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
/* make NaN quiet */
Set_invalidflag();
Sgl_set_quiet(opnd2);
Sgl_copytoptr(opnd2,dstptr);
return(NOEXCEPTION);
}
/*
* is third operand a signaling NaN?
*/
else if (Sgl_is_signalingnan(opnd3)) {
/* trap if INVALIDTRAP enabled */
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
/* make NaN quiet */
Set_invalidflag();
Sgl_set_quiet(opnd3);
Sgl_copytoptr(opnd3,dstptr);
return(NOEXCEPTION);
}
/*
* return quiet NaN
*/
Sgl_copytoptr(opnd1,dstptr);
return(NOEXCEPTION);
}
}
/*
* check second operand for NaN's or infinity
*/
if (Sgl_isinfinity_exponent(opnd2)) {
if (Sgl_iszero_mantissa(opnd2)) {
if (Sgl_isnotnan(opnd3)) {
if (Sgl_iszero_exponentmantissa(opnd1)) {
/*
* invalid since multiply operands are
* zero & infinity
*/
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
Set_invalidflag();
Sgl_makequietnan(opnd2);
Sgl_copytoptr(opnd2,dstptr);
return(NOEXCEPTION);
}
/*
* Check third operand for infinity with a
* sign opposite of the multiply result
*/
if (Sgl_isinfinity(opnd3) &&
(Sgl_sign(resultp1) ^ Sgl_sign(opnd3))) {
/*
* invalid since attempting a magnitude
* subtraction of infinities
*/
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
Set_invalidflag();
Sgl_makequietnan(resultp1);
Sgl_copytoptr(resultp1,dstptr);
return(NOEXCEPTION);
}
/*
* return infinity
*/
Sgl_setinfinity_exponentmantissa(resultp1);
Sgl_copytoptr(resultp1,dstptr);
return(NOEXCEPTION);
}
}
else {
/*
* is NaN; signaling or quiet?
*/
if (Sgl_isone_signaling(opnd2)) {
/* trap if INVALIDTRAP enabled */
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
/* make NaN quiet */
Set_invalidflag();
Sgl_set_quiet(opnd2);
}
/*
* is third operand a signaling NaN?
*/
else if (Sgl_is_signalingnan(opnd3)) {
/* trap if INVALIDTRAP enabled */
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
/* make NaN quiet */
Set_invalidflag();
Sgl_set_quiet(opnd3);
Sgl_copytoptr(opnd3,dstptr);
return(NOEXCEPTION);
}
/*
* return quiet NaN
*/
Sgl_copytoptr(opnd2,dstptr);
return(NOEXCEPTION);
}
}
/*
* check third operand for NaN's or infinity
*/
if (Sgl_isinfinity_exponent(opnd3)) {
if (Sgl_iszero_mantissa(opnd3)) {
/* return infinity */
Sgl_copytoptr(opnd3,dstptr);
return(NOEXCEPTION);
} else {
/*
* is NaN; signaling or quiet?
*/
if (Sgl_isone_signaling(opnd3)) {
/* trap if INVALIDTRAP enabled */
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
/* make NaN quiet */
Set_invalidflag();
Sgl_set_quiet(opnd3);
}
/*
* return quiet NaN
*/
Sgl_copytoptr(opnd3,dstptr);
return(NOEXCEPTION);
}
}
/*
* Generate multiply mantissa
*/
if (Sgl_isnotzero_exponent(opnd1)) {
/* set hidden bit */
Sgl_clear_signexponent_set_hidden(opnd1);
}
else {
/* check for zero */
if (Sgl_iszero_mantissa(opnd1)) {
/*
* Perform the add opnd3 with zero here.
*/
if (Sgl_iszero_exponentmantissa(opnd3)) {
if (Is_rounding_mode(ROUNDMINUS)) {
Sgl_or_signs(opnd3,resultp1);
} else {
Sgl_and_signs(opnd3,resultp1);
}
}
/*
* Now let's check for trapped underflow case.
*/
else if (Sgl_iszero_exponent(opnd3) &&
Is_underflowtrap_enabled()) {
/* need to normalize results mantissa */
sign_save = Sgl_signextendedsign(opnd3);
result_exponent = 0;
Sgl_leftshiftby1(opnd3);
Sgl_normalize(opnd3,result_exponent);
Sgl_set_sign(opnd3,/*using*/sign_save);
Sgl_setwrapped_exponent(opnd3,result_exponent,
unfl);
Sgl_copytoptr(opnd3,dstptr);
/* inexact = FALSE */
return(OPC_2E_UNDERFLOWEXCEPTION);
}
Sgl_copytoptr(opnd3,dstptr);
return(NOEXCEPTION);
}
/* is denormalized, adjust exponent */
Sgl_clear_signexponent(opnd1);
Sgl_leftshiftby1(opnd1);
Sgl_normalize(opnd1,mpy_exponent);
}
/* opnd2 needs to have hidden bit set with msb in hidden bit */
if (Sgl_isnotzero_exponent(opnd2)) {
Sgl_clear_signexponent_set_hidden(opnd2);
}
else {
/* check for zero */
if (Sgl_iszero_mantissa(opnd2)) {
/*
* Perform the add opnd3 with zero here.
*/
if (Sgl_iszero_exponentmantissa(opnd3)) {
if (Is_rounding_mode(ROUNDMINUS)) {
Sgl_or_signs(opnd3,resultp1);
} else {
Sgl_and_signs(opnd3,resultp1);
}
}
/*
* Now let's check for trapped underflow case.
*/
else if (Sgl_iszero_exponent(opnd3) &&
Is_underflowtrap_enabled()) {
/* need to normalize results mantissa */
sign_save = Sgl_signextendedsign(opnd3);
result_exponent = 0;
Sgl_leftshiftby1(opnd3);
Sgl_normalize(opnd3,result_exponent);
Sgl_set_sign(opnd3,/*using*/sign_save);
Sgl_setwrapped_exponent(opnd3,result_exponent,
unfl);
Sgl_copytoptr(opnd3,dstptr);
/* inexact = FALSE */
return(OPC_2E_UNDERFLOWEXCEPTION);
}
Sgl_copytoptr(opnd3,dstptr);
return(NOEXCEPTION);
}
/* is denormalized; want to normalize */
Sgl_clear_signexponent(opnd2);
Sgl_leftshiftby1(opnd2);
Sgl_normalize(opnd2,mpy_exponent);
}
/* Multiply the first two source mantissas together */
/*
* The intermediate result will be kept in tmpres,
* which needs enough room for 106 bits of mantissa,
* so lets call it a Double extended.
*/
Sglext_setzero(tmpresp1,tmpresp2);
/*
* Four bits at a time are inspected in each loop, and a
* simple shift and add multiply algorithm is used.
*/
for (count = SGL_P-1; count >= 0; count -= 4) {
Sglext_rightshiftby4(tmpresp1,tmpresp2);
if (Sbit28(opnd1)) {
/* Twoword_add should be an ADD followed by 2 ADDC's */
Twoword_add(tmpresp1, tmpresp2, opnd2<<3, 0);
}
if (Sbit29(opnd1)) {
Twoword_add(tmpresp1, tmpresp2, opnd2<<2, 0);
}
if (Sbit30(opnd1)) {
Twoword_add(tmpresp1, tmpresp2, opnd2<<1, 0);
}
if (Sbit31(opnd1)) {
Twoword_add(tmpresp1, tmpresp2, opnd2, 0);
}
Sgl_rightshiftby4(opnd1);
}
if (Is_sexthiddenoverflow(tmpresp1)) {
/* result mantissa >= 2 (mantissa overflow) */
mpy_exponent++;
Sglext_rightshiftby4(tmpresp1,tmpresp2);
} else {
Sglext_rightshiftby3(tmpresp1,tmpresp2);
}
/*
* Restore the sign of the mpy result which was saved in resultp1.
* The exponent will continue to be kept in mpy_exponent.
*/
Sglext_set_sign(tmpresp1,Sgl_sign(resultp1));
/*
* No rounding is required, since the result of the multiply
* is exact in the extended format.
*/
/*
* Now we are ready to perform the add portion of the operation.
*
* The exponents need to be kept as integers for now, since the
* multiply result might not fit into the exponent field. We
* can't overflow or underflow because of this yet, since the
* add could bring the final result back into range.
*/
add_exponent = Sgl_exponent(opnd3);
/*
* Check for denormalized or zero add operand.
*/
if (add_exponent == 0) {
/* check for zero */
if (Sgl_iszero_mantissa(opnd3)) {
/* right is zero */
/* Left can't be zero and must be result.
*
* The final result is now in tmpres and mpy_exponent,
* and needs to be rounded and squeezed back into
* double precision format from double extended.
*/
result_exponent = mpy_exponent;
Sglext_copy(tmpresp1,tmpresp2,resultp1,resultp2);
sign_save = Sgl_signextendedsign(resultp1);/*save sign*/
goto round;
}
/*
* Neither are zeroes.
* Adjust exponent and normalize add operand.
*/
sign_save = Sgl_signextendedsign(opnd3); /* save sign */
Sgl_clear_signexponent(opnd3);
Sgl_leftshiftby1(opnd3);
Sgl_normalize(opnd3,add_exponent);
Sgl_set_sign(opnd3,sign_save); /* restore sign */
} else {
Sgl_clear_exponent_set_hidden(opnd3);
}
/*
* Copy opnd3 to the double extended variable called right.
*/
Sgl_copyto_sglext(opnd3,rightp1,rightp2);
/*
* A zero "save" helps discover equal operands (for later),
* and is used in swapping operands (if needed).
*/
Sglext_xortointp1(tmpresp1,rightp1,/*to*/save);
/*
* Compare magnitude of operands.
*/
Sglext_copytoint_exponentmantissa(tmpresp1,signlessleft1);
Sglext_copytoint_exponentmantissa(rightp1,signlessright1);
if (mpy_exponent < add_exponent || mpy_exponent == add_exponent &&
Sglext_ismagnitudeless(signlessleft1,signlessright1)) {
/*
* Set the left operand to the larger one by XOR swap.
* First finish the first word "save".
*/
Sglext_xorfromintp1(save,rightp1,/*to*/rightp1);
Sglext_xorfromintp1(save,tmpresp1,/*to*/tmpresp1);
Sglext_swap_lower(tmpresp2,rightp2);
/* also setup exponents used in rest of routine */
diff_exponent = add_exponent - mpy_exponent;
result_exponent = add_exponent;
} else {
/* also setup exponents used in rest of routine */
diff_exponent = mpy_exponent - add_exponent;
result_exponent = mpy_exponent;
}
/* Invariant: left is not smaller than right. */
/*
* Special case alignment of operands that would force alignment
* beyond the extent of the extension. A further optimization
* could special case this but only reduces the path length for
* this infrequent case.
*/
if (diff_exponent > SGLEXT_THRESHOLD) {
diff_exponent = SGLEXT_THRESHOLD;
}
/* Align right operand by shifting it to the right */
Sglext_clear_sign(rightp1);
Sglext_right_align(rightp1,rightp2,/*shifted by*/diff_exponent);
/* Treat sum and difference of the operands separately. */
if ((int)save < 0) {
/*
* Difference of the two operands. Overflow can occur if the
* multiply overflowed. A borrow can occur out of the hidden
* bit and force a post normalization phase.
*/
Sglext_subtract(tmpresp1,tmpresp2, rightp1,rightp2,
resultp1,resultp2);
sign_save = Sgl_signextendedsign(resultp1);
if (Sgl_iszero_hidden(resultp1)) {
/* Handle normalization */
/* A straight foward algorithm would now shift the
* result and extension left until the hidden bit
* becomes one. Not all of the extension bits need
* participate in the shift. Only the two most
* significant bits (round and guard) are needed.
* If only a single shift is needed then the guard
* bit becomes a significant low order bit and the
* extension must participate in the rounding.
* If more than a single shift is needed, then all
* bits to the right of the guard bit are zeros,
* and the guard bit may or may not be zero. */
Sglext_leftshiftby1(resultp1,resultp2);
/* Need to check for a zero result. The sign and
* exponent fields have already been zeroed. The more
* efficient test of the full object can be used.
*/
if (Sglext_iszero(resultp1,resultp2)) {
/* Must have been "x-x" or "x+(-x)". */
if (Is_rounding_mode(ROUNDMINUS))
Sgl_setone_sign(resultp1);
Sgl_copytoptr(resultp1,dstptr);
return(NOEXCEPTION);
}
result_exponent--;
/* Look to see if normalization is finished. */
if (Sgl_isone_hidden(resultp1)) {
/* No further normalization is needed */
goto round;
}
/* Discover first one bit to determine shift amount.
* Use a modified binary search. We have already
* shifted the result one position right and still
* not found a one so the remainder of the extension
* must be zero and simplifies rounding. */
/* Scan bytes */
while (Sgl_iszero_hiddenhigh7mantissa(resultp1)) {
Sglext_leftshiftby8(resultp1,resultp2);
result_exponent -= 8;
}
/* Now narrow it down to the nibble */
if (Sgl_iszero_hiddenhigh3mantissa(resultp1)) {
/* The lower nibble contains the
* normalizing one */
Sglext_leftshiftby4(resultp1,resultp2);
result_exponent -= 4;
}
/* Select case where first bit is set (already
* normalized) otherwise select the proper shift. */
jumpsize = Sgl_hiddenhigh3mantissa(resultp1);
if (jumpsize <= 7) switch(jumpsize) {
case 1:
Sglext_leftshiftby3(resultp1,resultp2);
result_exponent -= 3;
break;
case 2:
case 3:
Sglext_leftshiftby2(resultp1,resultp2);
result_exponent -= 2;
break;
case 4:
case 5:
case 6:
case 7:
Sglext_leftshiftby1(resultp1,resultp2);
result_exponent -= 1;
break;
}
} /* end if (hidden...)... */
/* Fall through and round */
} /* end if (save < 0)... */
else {
/* Add magnitudes */
Sglext_addition(tmpresp1,tmpresp2,
rightp1,rightp2, /*to*/resultp1,resultp2);
sign_save = Sgl_signextendedsign(resultp1);
if (Sgl_isone_hiddenoverflow(resultp1)) {
/* Prenormalization required. */
Sglext_arithrightshiftby1(resultp1,resultp2);
result_exponent++;
} /* end if hiddenoverflow... */
} /* end else ...add magnitudes... */
/* Round the result. If the extension and lower two words are
* all zeros, then the result is exact. Otherwise round in the
* correct direction. Underflow is possible. If a postnormalization
* is necessary, then the mantissa is all zeros so no shift is needed.
*/
round:
if (result_exponent <= 0 && !Is_underflowtrap_enabled()) {
Sglext_denormalize(resultp1,resultp2,result_exponent,is_tiny);
}
Sgl_set_sign(resultp1,/*using*/sign_save);
if (Sglext_isnotzero_mantissap2(resultp2)) {
inexact = TRUE;
switch(Rounding_mode()) {
case ROUNDNEAREST: /* The default. */
if (Sglext_isone_highp2(resultp2)) {
/* at least 1/2 ulp */
if (Sglext_isnotzero_low31p2(resultp2) ||
Sglext_isone_lowp1(resultp1)) {
/* either exactly half way and odd or
* more than 1/2ulp */
Sgl_increment(resultp1);
}
}
break;
case ROUNDPLUS:
if (Sgl_iszero_sign(resultp1)) {
/* Round up positive results */
Sgl_increment(resultp1);
}
break;
case ROUNDMINUS:
if (Sgl_isone_sign(resultp1)) {
/* Round down negative results */
Sgl_increment(resultp1);
}
case ROUNDZERO:;
/* truncate is simple */
} /* end switch... */
if (Sgl_isone_hiddenoverflow(resultp1)) result_exponent++;
}
if (result_exponent >= SGL_INFINITY_EXPONENT) {
/* Overflow */
if (Is_overflowtrap_enabled()) {
/*
* Adjust bias of result
*/
Sgl_setwrapped_exponent(resultp1,result_exponent,ovfl);
Sgl_copytoptr(resultp1,dstptr);
if (inexact)
if (Is_inexacttrap_enabled())
return (OPC_2E_OVERFLOWEXCEPTION |
OPC_2E_INEXACTEXCEPTION);
else Set_inexactflag();
return (OPC_2E_OVERFLOWEXCEPTION);
}
inexact = TRUE;
Set_overflowflag();
Sgl_setoverflow(resultp1);
} else if (result_exponent <= 0) { /* underflow case */
if (Is_underflowtrap_enabled()) {
/*
* Adjust bias of result
*/
Sgl_setwrapped_exponent(resultp1,result_exponent,unfl);
Sgl_copytoptr(resultp1,dstptr);
if (inexact)
if (Is_inexacttrap_enabled())
return (OPC_2E_UNDERFLOWEXCEPTION |
OPC_2E_INEXACTEXCEPTION);
else Set_inexactflag();
return(OPC_2E_UNDERFLOWEXCEPTION);
}
else if (inexact && is_tiny) Set_underflowflag();
}
else Sgl_set_exponent(resultp1,result_exponent);
Sgl_copytoptr(resultp1,dstptr);
if (inexact)
if (Is_inexacttrap_enabled()) return(OPC_2E_INEXACTEXCEPTION);
else Set_inexactflag();
return(NOEXCEPTION);
}
/*
* Single Floating-point Multiply Negate Fused Add
*/
sgl_fmpynfadd(src1ptr,src2ptr,src3ptr,status,dstptr)
sgl_floating_point *src1ptr, *src2ptr, *src3ptr, *dstptr;
unsigned int *status;
{
unsigned int opnd1, opnd2, opnd3;
register unsigned int tmpresp1, tmpresp2;
unsigned int rightp1, rightp2;
unsigned int resultp1, resultp2 = 0;
register int mpy_exponent, add_exponent, count;
boolean inexact = FALSE, is_tiny = FALSE;
unsigned int signlessleft1, signlessright1, save;
register int result_exponent, diff_exponent;
int sign_save, jumpsize;
Sgl_copyfromptr(src1ptr,opnd1);
Sgl_copyfromptr(src2ptr,opnd2);
Sgl_copyfromptr(src3ptr,opnd3);
/*
* set sign bit of result of multiply
*/
if (Sgl_sign(opnd1) ^ Sgl_sign(opnd2))
Sgl_setzero(resultp1);
else
Sgl_setnegativezero(resultp1);
/*
* Generate multiply exponent
*/
mpy_exponent = Sgl_exponent(opnd1) + Sgl_exponent(opnd2) - SGL_BIAS;
/*
* check first operand for NaN's or infinity
*/
if (Sgl_isinfinity_exponent(opnd1)) {
if (Sgl_iszero_mantissa(opnd1)) {
if (Sgl_isnotnan(opnd2) && Sgl_isnotnan(opnd3)) {
if (Sgl_iszero_exponentmantissa(opnd2)) {
/*
* invalid since operands are infinity
* and zero
*/
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
Set_invalidflag();
Sgl_makequietnan(resultp1);
Sgl_copytoptr(resultp1,dstptr);
return(NOEXCEPTION);
}
/*
* Check third operand for infinity with a
* sign opposite of the multiply result
*/
if (Sgl_isinfinity(opnd3) &&
(Sgl_sign(resultp1) ^ Sgl_sign(opnd3))) {
/*
* invalid since attempting a magnitude
* subtraction of infinities
*/
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
Set_invalidflag();
Sgl_makequietnan(resultp1);
Sgl_copytoptr(resultp1,dstptr);
return(NOEXCEPTION);
}
/*
* return infinity
*/
Sgl_setinfinity_exponentmantissa(resultp1);
Sgl_copytoptr(resultp1,dstptr);
return(NOEXCEPTION);
}
}
else {
/*
* is NaN; signaling or quiet?
*/
if (Sgl_isone_signaling(opnd1)) {
/* trap if INVALIDTRAP enabled */
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
/* make NaN quiet */
Set_invalidflag();
Sgl_set_quiet(opnd1);
}
/*
* is second operand a signaling NaN?
*/
else if (Sgl_is_signalingnan(opnd2)) {
/* trap if INVALIDTRAP enabled */
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
/* make NaN quiet */
Set_invalidflag();
Sgl_set_quiet(opnd2);
Sgl_copytoptr(opnd2,dstptr);
return(NOEXCEPTION);
}
/*
* is third operand a signaling NaN?
*/
else if (Sgl_is_signalingnan(opnd3)) {
/* trap if INVALIDTRAP enabled */
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
/* make NaN quiet */
Set_invalidflag();
Sgl_set_quiet(opnd3);
Sgl_copytoptr(opnd3,dstptr);
return(NOEXCEPTION);
}
/*
* return quiet NaN
*/
Sgl_copytoptr(opnd1,dstptr);
return(NOEXCEPTION);
}
}
/*
* check second operand for NaN's or infinity
*/
if (Sgl_isinfinity_exponent(opnd2)) {
if (Sgl_iszero_mantissa(opnd2)) {
if (Sgl_isnotnan(opnd3)) {
if (Sgl_iszero_exponentmantissa(opnd1)) {
/*
* invalid since multiply operands are
* zero & infinity
*/
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
Set_invalidflag();
Sgl_makequietnan(opnd2);
Sgl_copytoptr(opnd2,dstptr);
return(NOEXCEPTION);
}
/*
* Check third operand for infinity with a
* sign opposite of the multiply result
*/
if (Sgl_isinfinity(opnd3) &&
(Sgl_sign(resultp1) ^ Sgl_sign(opnd3))) {
/*
* invalid since attempting a magnitude
* subtraction of infinities
*/
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
Set_invalidflag();
Sgl_makequietnan(resultp1);
Sgl_copytoptr(resultp1,dstptr);
return(NOEXCEPTION);
}
/*
* return infinity
*/
Sgl_setinfinity_exponentmantissa(resultp1);
Sgl_copytoptr(resultp1,dstptr);
return(NOEXCEPTION);
}
}
else {
/*
* is NaN; signaling or quiet?
*/
if (Sgl_isone_signaling(opnd2)) {
/* trap if INVALIDTRAP enabled */
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
/* make NaN quiet */
Set_invalidflag();
Sgl_set_quiet(opnd2);
}
/*
* is third operand a signaling NaN?
*/
else if (Sgl_is_signalingnan(opnd3)) {
/* trap if INVALIDTRAP enabled */
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
/* make NaN quiet */
Set_invalidflag();
Sgl_set_quiet(opnd3);
Sgl_copytoptr(opnd3,dstptr);
return(NOEXCEPTION);
}
/*
* return quiet NaN
*/
Sgl_copytoptr(opnd2,dstptr);
return(NOEXCEPTION);
}
}
/*
* check third operand for NaN's or infinity
*/
if (Sgl_isinfinity_exponent(opnd3)) {
if (Sgl_iszero_mantissa(opnd3)) {
/* return infinity */
Sgl_copytoptr(opnd3,dstptr);
return(NOEXCEPTION);
} else {
/*
* is NaN; signaling or quiet?
*/
if (Sgl_isone_signaling(opnd3)) {
/* trap if INVALIDTRAP enabled */
if (Is_invalidtrap_enabled())
return(OPC_2E_INVALIDEXCEPTION);
/* make NaN quiet */
Set_invalidflag();
Sgl_set_quiet(opnd3);
}
/*
* return quiet NaN
*/
Sgl_copytoptr(opnd3,dstptr);
return(NOEXCEPTION);
}
}
/*
* Generate multiply mantissa
*/
if (Sgl_isnotzero_exponent(opnd1)) {
/* set hidden bit */
Sgl_clear_signexponent_set_hidden(opnd1);
}
else {
/* check for zero */
if (Sgl_iszero_mantissa(opnd1)) {
/*
* Perform the add opnd3 with zero here.
*/
if (Sgl_iszero_exponentmantissa(opnd3)) {
if (Is_rounding_mode(ROUNDMINUS)) {
Sgl_or_signs(opnd3,resultp1);
} else {
Sgl_and_signs(opnd3,resultp1);
}
}
/*
* Now let's check for trapped underflow case.
*/
else if (Sgl_iszero_exponent(opnd3) &&
Is_underflowtrap_enabled()) {
/* need to normalize results mantissa */
sign_save = Sgl_signextendedsign(opnd3);
result_exponent = 0;
Sgl_leftshiftby1(opnd3);
Sgl_normalize(opnd3,result_exponent);
Sgl_set_sign(opnd3,/*using*/sign_save);
Sgl_setwrapped_exponent(opnd3,result_exponent,
unfl);
Sgl_copytoptr(opnd3,dstptr);
/* inexact = FALSE */
return(OPC_2E_UNDERFLOWEXCEPTION);
}
Sgl_copytoptr(opnd3,dstptr);
return(NOEXCEPTION);
}
/* is denormalized, adjust exponent */
Sgl_clear_signexponent(opnd1);
Sgl_leftshiftby1(opnd1);
Sgl_normalize(opnd1,mpy_exponent);
}
/* opnd2 needs to have hidden bit set with msb in hidden bit */
if (Sgl_isnotzero_exponent(opnd2)) {
Sgl_clear_signexponent_set_hidden(opnd2);
}
else {
/* check for zero */
if (Sgl_iszero_mantissa(opnd2)) {
/*
* Perform the add opnd3 with zero here.
*/
if (Sgl_iszero_exponentmantissa(opnd3)) {
if (Is_rounding_mode(ROUNDMINUS)) {
Sgl_or_signs(opnd3,resultp1);
} else {
Sgl_and_signs(opnd3,resultp1);
}
}
/*
* Now let's check for trapped underflow case.
*/
else if (Sgl_iszero_exponent(opnd3) &&
Is_underflowtrap_enabled()) {
/* need to normalize results mantissa */
sign_save = Sgl_signextendedsign(opnd3);
result_exponent = 0;
Sgl_leftshiftby1(opnd3);
Sgl_normalize(opnd3,result_exponent);
Sgl_set_sign(opnd3,/*using*/sign_save);
Sgl_setwrapped_exponent(opnd3,result_exponent,
unfl);
Sgl_copytoptr(opnd3,dstptr);
/* inexact = FALSE */
return(OPC_2E_UNDERFLOWEXCEPTION);
}
Sgl_copytoptr(opnd3,dstptr);
return(NOEXCEPTION);
}
/* is denormalized; want to normalize */
Sgl_clear_signexponent(opnd2);
Sgl_leftshiftby1(opnd2);
Sgl_normalize(opnd2,mpy_exponent);
}
/* Multiply the first two source mantissas together */
/*
* The intermediate result will be kept in tmpres,
* which needs enough room for 106 bits of mantissa,
* so lets call it a Double extended.
*/
Sglext_setzero(tmpresp1,tmpresp2);
/*
* Four bits at a time are inspected in each loop, and a
* simple shift and add multiply algorithm is used.
*/
for (count = SGL_P-1; count >= 0; count -= 4) {
Sglext_rightshiftby4(tmpresp1,tmpresp2);
if (Sbit28(opnd1)) {
/* Twoword_add should be an ADD followed by 2 ADDC's */
Twoword_add(tmpresp1, tmpresp2, opnd2<<3, 0);
}
if (Sbit29(opnd1)) {
Twoword_add(tmpresp1, tmpresp2, opnd2<<2, 0);
}
if (Sbit30(opnd1)) {
Twoword_add(tmpresp1, tmpresp2, opnd2<<1, 0);
}
if (Sbit31(opnd1)) {
Twoword_add(tmpresp1, tmpresp2, opnd2, 0);
}
Sgl_rightshiftby4(opnd1);
}
if (Is_sexthiddenoverflow(tmpresp1)) {
/* result mantissa >= 2 (mantissa overflow) */
mpy_exponent++;
Sglext_rightshiftby4(tmpresp1,tmpresp2);
} else {
Sglext_rightshiftby3(tmpresp1,tmpresp2);
}
/*
* Restore the sign of the mpy result which was saved in resultp1.
* The exponent will continue to be kept in mpy_exponent.
*/
Sglext_set_sign(tmpresp1,Sgl_sign(resultp1));
/*
* No rounding is required, since the result of the multiply
* is exact in the extended format.
*/
/*
* Now we are ready to perform the add portion of the operation.
*
* The exponents need to be kept as integers for now, since the
* multiply result might not fit into the exponent field. We
* can't overflow or underflow because of this yet, since the
* add could bring the final result back into range.
*/
add_exponent = Sgl_exponent(opnd3);
/*
* Check for denormalized or zero add operand.
*/
if (add_exponent == 0) {
/* check for zero */
if (Sgl_iszero_mantissa(opnd3)) {
/* right is zero */
/* Left can't be zero and must be result.
*
* The final result is now in tmpres and mpy_exponent,
* and needs to be rounded and squeezed back into
* double precision format from double extended.
*/
result_exponent = mpy_exponent;
Sglext_copy(tmpresp1,tmpresp2,resultp1,resultp2);
sign_save = Sgl_signextendedsign(resultp1);/*save sign*/
goto round;
}
/*
* Neither are zeroes.
* Adjust exponent and normalize add operand.
*/
sign_save = Sgl_signextendedsign(opnd3); /* save sign */
Sgl_clear_signexponent(opnd3);
Sgl_leftshiftby1(opnd3);
Sgl_normalize(opnd3,add_exponent);
Sgl_set_sign(opnd3,sign_save); /* restore sign */
} else {
Sgl_clear_exponent_set_hidden(opnd3);
}
/*
* Copy opnd3 to the double extended variable called right.
*/
Sgl_copyto_sglext(opnd3,rightp1,rightp2);
/*
* A zero "save" helps discover equal operands (for later),
* and is used in swapping operands (if needed).
*/
Sglext_xortointp1(tmpresp1,rightp1,/*to*/save);
/*
* Compare magnitude of operands.
*/
Sglext_copytoint_exponentmantissa(tmpresp1,signlessleft1);
Sglext_copytoint_exponentmantissa(rightp1,signlessright1);
if (mpy_exponent < add_exponent || mpy_exponent == add_exponent &&
Sglext_ismagnitudeless(signlessleft1,signlessright1)) {
/*
* Set the left operand to the larger one by XOR swap.
* First finish the first word "save".
*/
Sglext_xorfromintp1(save,rightp1,/*to*/rightp1);
Sglext_xorfromintp1(save,tmpresp1,/*to*/tmpresp1);
Sglext_swap_lower(tmpresp2,rightp2);
/* also setup exponents used in rest of routine */
diff_exponent = add_exponent - mpy_exponent;
result_exponent = add_exponent;
} else {
/* also setup exponents used in rest of routine */
diff_exponent = mpy_exponent - add_exponent;
result_exponent = mpy_exponent;
}
/* Invariant: left is not smaller than right. */
/*
* Special case alignment of operands that would force alignment
* beyond the extent of the extension. A further optimization
* could special case this but only reduces the path length for
* this infrequent case.
*/
if (diff_exponent > SGLEXT_THRESHOLD) {
diff_exponent = SGLEXT_THRESHOLD;
}
/* Align right operand by shifting it to the right */
Sglext_clear_sign(rightp1);
Sglext_right_align(rightp1,rightp2,/*shifted by*/diff_exponent);
/* Treat sum and difference of the operands separately. */
if ((int)save < 0) {
/*
* Difference of the two operands. Overflow can occur if the
* multiply overflowed. A borrow can occur out of the hidden
* bit and force a post normalization phase.
*/
Sglext_subtract(tmpresp1,tmpresp2, rightp1,rightp2,
resultp1,resultp2);
sign_save = Sgl_signextendedsign(resultp1);
if (Sgl_iszero_hidden(resultp1)) {
/* Handle normalization */
/* A straight foward algorithm would now shift the
* result and extension left until the hidden bit
* becomes one. Not all of the extension bits need
* participate in the shift. Only the two most
* significant bits (round and guard) are needed.
* If only a single shift is needed then the guard
* bit becomes a significant low order bit and the
* extension must participate in the rounding.
* If more than a single shift is needed, then all
* bits to the right of the guard bit are zeros,
* and the guard bit may or may not be zero. */
Sglext_leftshiftby1(resultp1,resultp2);
/* Need to check for a zero result. The sign and
* exponent fields have already been zeroed. The more
* efficient test of the full object can be used.
*/
if (Sglext_iszero(resultp1,resultp2)) {
/* Must have been "x-x" or "x+(-x)". */
if (Is_rounding_mode(ROUNDMINUS))
Sgl_setone_sign(resultp1);
Sgl_copytoptr(resultp1,dstptr);
return(NOEXCEPTION);
}
result_exponent--;
/* Look to see if normalization is finished. */
if (Sgl_isone_hidden(resultp1)) {
/* No further normalization is needed */
goto round;
}
/* Discover first one bit to determine shift amount.
* Use a modified binary search. We have already
* shifted the result one position right and still
* not found a one so the remainder of the extension
* must be zero and simplifies rounding. */
/* Scan bytes */
while (Sgl_iszero_hiddenhigh7mantissa(resultp1)) {
Sglext_leftshiftby8(resultp1,resultp2);
result_exponent -= 8;
}
/* Now narrow it down to the nibble */
if (Sgl_iszero_hiddenhigh3mantissa(resultp1)) {
/* The lower nibble contains the
* normalizing one */
Sglext_leftshiftby4(resultp1,resultp2);
result_exponent -= 4;
}
/* Select case where first bit is set (already
* normalized) otherwise select the proper shift. */
jumpsize = Sgl_hiddenhigh3mantissa(resultp1);
if (jumpsize <= 7) switch(jumpsize) {
case 1:
Sglext_leftshiftby3(resultp1,resultp2);
result_exponent -= 3;
break;
case 2:
case 3:
Sglext_leftshiftby2(resultp1,resultp2);
result_exponent -= 2;
break;
case 4:
case 5:
case 6:
case 7:
Sglext_leftshiftby1(resultp1,resultp2);
result_exponent -= 1;
break;
}
} /* end if (hidden...)... */
/* Fall through and round */
} /* end if (save < 0)... */
else {
/* Add magnitudes */
Sglext_addition(tmpresp1,tmpresp2,
rightp1,rightp2, /*to*/resultp1,resultp2);
sign_save = Sgl_signextendedsign(resultp1);
if (Sgl_isone_hiddenoverflow(resultp1)) {
/* Prenormalization required. */
Sglext_arithrightshiftby1(resultp1,resultp2);
result_exponent++;
} /* end if hiddenoverflow... */
} /* end else ...add magnitudes... */
/* Round the result. If the extension and lower two words are
* all zeros, then the result is exact. Otherwise round in the
* correct direction. Underflow is possible. If a postnormalization
* is necessary, then the mantissa is all zeros so no shift is needed.
*/
round:
if (result_exponent <= 0 && !Is_underflowtrap_enabled()) {
Sglext_denormalize(resultp1,resultp2,result_exponent,is_tiny);
}
Sgl_set_sign(resultp1,/*using*/sign_save);
if (Sglext_isnotzero_mantissap2(resultp2)) {
inexact = TRUE;
switch(Rounding_mode()) {
case ROUNDNEAREST: /* The default. */
if (Sglext_isone_highp2(resultp2)) {
/* at least 1/2 ulp */
if (Sglext_isnotzero_low31p2(resultp2) ||
Sglext_isone_lowp1(resultp1)) {
/* either exactly half way and odd or
* more than 1/2ulp */
Sgl_increment(resultp1);
}
}
break;
case ROUNDPLUS:
if (Sgl_iszero_sign(resultp1)) {
/* Round up positive results */
Sgl_increment(resultp1);
}
break;
case ROUNDMINUS:
if (Sgl_isone_sign(resultp1)) {
/* Round down negative results */
Sgl_increment(resultp1);
}
case ROUNDZERO:;
/* truncate is simple */
} /* end switch... */
if (Sgl_isone_hiddenoverflow(resultp1)) result_exponent++;
}
if (result_exponent >= SGL_INFINITY_EXPONENT) {
/* Overflow */
if (Is_overflowtrap_enabled()) {
/*
* Adjust bias of result
*/
Sgl_setwrapped_exponent(resultp1,result_exponent,ovfl);
Sgl_copytoptr(resultp1,dstptr);
if (inexact)
if (Is_inexacttrap_enabled())
return (OPC_2E_OVERFLOWEXCEPTION |
OPC_2E_INEXACTEXCEPTION);
else Set_inexactflag();
return (OPC_2E_OVERFLOWEXCEPTION);
}
inexact = TRUE;
Set_overflowflag();
Sgl_setoverflow(resultp1);
} else if (result_exponent <= 0) { /* underflow case */
if (Is_underflowtrap_enabled()) {
/*
* Adjust bias of result
*/
Sgl_setwrapped_exponent(resultp1,result_exponent,unfl);
Sgl_copytoptr(resultp1,dstptr);
if (inexact)
if (Is_inexacttrap_enabled())
return (OPC_2E_UNDERFLOWEXCEPTION |
OPC_2E_INEXACTEXCEPTION);
else Set_inexactflag();
return(OPC_2E_UNDERFLOWEXCEPTION);
}
else if (inexact && is_tiny) Set_underflowflag();
}
else Sgl_set_exponent(resultp1,result_exponent);
Sgl_copytoptr(resultp1,dstptr);
if (inexact)
if (Is_inexacttrap_enabled()) return(OPC_2E_INEXACTEXCEPTION);
else Set_inexactflag();
return(NOEXCEPTION);
}
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