forked from Minki/linux
MPILIB: Provide count_leading/trailing_zeros() based on arch functions
Provide count_leading/trailing_zeros() macros based on extant arch bit scanning functions rather than reimplementing from scratch in MPILIB. Whilst we're at it, turn count_foo_zeros(n, x) into n = count_foo_zeros(x). Also move the definition to asm-generic as other people may be interested in using it. Signed-off-by: David Howells <dhowells@redhat.com> Cc: David S. Miller <davem@davemloft.net> Cc: Dmitry Kasatkin <dmitry.kasatkin@intel.com> Cc: Arnd Bergmann <arnd@arndb.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
David Howells
Rusty Russell
parent
cf7f601c06
commit
aacf29bf1b
57
include/asm-generic/bitops/count_zeros.h
Normal file
57
include/asm-generic/bitops/count_zeros.h
Normal file
@ -0,0 +1,57 @@
|
||||
/* Count leading and trailing zeros functions
|
||||
*
|
||||
* Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
|
||||
* Written by David Howells (dhowells@redhat.com)
|
||||
*
|
||||
* This program is free software; you can redistribute it and/or
|
||||
* modify it under the terms of the GNU General Public Licence
|
||||
* as published by the Free Software Foundation; either version
|
||||
* 2 of the Licence, or (at your option) any later version.
|
||||
*/
|
||||
|
||||
#ifndef _ASM_GENERIC_BITOPS_COUNT_ZEROS_H_
|
||||
#define _ASM_GENERIC_BITOPS_COUNT_ZEROS_H_
|
||||
|
||||
#include <asm/bitops.h>
|
||||
|
||||
/**
|
||||
* count_leading_zeros - Count the number of zeros from the MSB back
|
||||
* @x: The value
|
||||
*
|
||||
* Count the number of leading zeros from the MSB going towards the LSB in @x.
|
||||
*
|
||||
* If the MSB of @x is set, the result is 0.
|
||||
* If only the LSB of @x is set, then the result is BITS_PER_LONG-1.
|
||||
* If @x is 0 then the result is COUNT_LEADING_ZEROS_0.
|
||||
*/
|
||||
static inline int count_leading_zeros(unsigned long x)
|
||||
{
|
||||
if (sizeof(x) == 4)
|
||||
return BITS_PER_LONG - fls(x);
|
||||
else
|
||||
return BITS_PER_LONG - fls64(x);
|
||||
}
|
||||
|
||||
#define COUNT_LEADING_ZEROS_0 BITS_PER_LONG
|
||||
|
||||
/**
|
||||
* count_trailing_zeros - Count the number of zeros from the LSB forwards
|
||||
* @x: The value
|
||||
*
|
||||
* Count the number of trailing zeros from the LSB going towards the MSB in @x.
|
||||
*
|
||||
* If the LSB of @x is set, the result is 0.
|
||||
* If only the MSB of @x is set, then the result is BITS_PER_LONG-1.
|
||||
* If @x is 0 then the result is COUNT_TRAILING_ZEROS_0.
|
||||
*/
|
||||
static inline int count_trailing_zeros(unsigned long x)
|
||||
{
|
||||
#define COUNT_TRAILING_ZEROS_0 (-1)
|
||||
|
||||
if (sizeof(x) == 4)
|
||||
return ffs(x);
|
||||
else
|
||||
return (x != 0) ? __ffs(x) : COUNT_TRAILING_ZEROS_0;
|
||||
}
|
||||
|
||||
#endif /* _ASM_GENERIC_BITOPS_COUNT_ZEROS_H_ */
|
||||
@ -19,6 +19,8 @@
|
||||
* the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
|
||||
* MA 02111-1307, USA. */
|
||||
|
||||
#include <asm-generic/bitops/count_zeros.h>
|
||||
|
||||
/* You have to define the following before including this file:
|
||||
*
|
||||
* UWtype -- An unsigned type, default type for operations (typically a "word")
|
||||
@ -146,12 +148,6 @@ do { \
|
||||
: "1" ((USItype)(n1)), \
|
||||
"r" ((USItype)(n0)), \
|
||||
"r" ((USItype)(d)))
|
||||
|
||||
#define count_leading_zeros(count, x) \
|
||||
__asm__ ("clz %0,%1" \
|
||||
: "=r" ((USItype)(count)) \
|
||||
: "r" ((USItype)(x)))
|
||||
#define COUNT_LEADING_ZEROS_0 32
|
||||
#endif /* __a29k__ */
|
||||
|
||||
#if defined(__alpha) && W_TYPE_SIZE == 64
|
||||
@ -298,11 +294,6 @@ extern UDItype __udiv_qrnnd();
|
||||
: "1" ((USItype)(nh)), \
|
||||
"0" ((USItype)(nl)), \
|
||||
"g" ((USItype)(d)))
|
||||
#define count_leading_zeros(count, x) \
|
||||
__asm__ ("bsch/1 %1,%0" \
|
||||
: "=g" (count) \
|
||||
: "g" ((USItype)(x)), \
|
||||
"0" ((USItype)0))
|
||||
#endif
|
||||
|
||||
/***************************************
|
||||
@ -354,27 +345,6 @@ do { USItype __r; \
|
||||
} while (0)
|
||||
extern USItype __udiv_qrnnd();
|
||||
#endif /* LONGLONG_STANDALONE */
|
||||
#define count_leading_zeros(count, x) \
|
||||
do { \
|
||||
USItype __tmp; \
|
||||
__asm__ ( \
|
||||
"ldi 1,%0\n" \
|
||||
"extru,= %1,15,16,%%r0 ; Bits 31..16 zero?\n" \
|
||||
"extru,tr %1,15,16,%1 ; No. Shift down, skip add.\n" \
|
||||
"ldo 16(%0),%0 ; Yes. Perform add.\n" \
|
||||
"extru,= %1,23,8,%%r0 ; Bits 15..8 zero?\n" \
|
||||
"extru,tr %1,23,8,%1 ; No. Shift down, skip add.\n" \
|
||||
"ldo 8(%0),%0 ; Yes. Perform add.\n" \
|
||||
"extru,= %1,27,4,%%r0 ; Bits 7..4 zero?\n" \
|
||||
"extru,tr %1,27,4,%1 ; No. Shift down, skip add.\n" \
|
||||
"ldo 4(%0),%0 ; Yes. Perform add.\n" \
|
||||
"extru,= %1,29,2,%%r0 ; Bits 3..2 zero?\n" \
|
||||
"extru,tr %1,29,2,%1 ; No. Shift down, skip add.\n" \
|
||||
"ldo 2(%0),%0 ; Yes. Perform add.\n" \
|
||||
"extru %1,30,1,%1 ; Extract bit 1.\n" \
|
||||
"sub %0,%1,%0 ; Subtract it. " \
|
||||
: "=r" (count), "=r" (__tmp) : "1" (x)); \
|
||||
} while (0)
|
||||
#endif /* hppa */
|
||||
|
||||
/***************************************
|
||||
@ -457,15 +427,6 @@ do { \
|
||||
: "0" ((USItype)(n0)), \
|
||||
"1" ((USItype)(n1)), \
|
||||
"rm" ((USItype)(d)))
|
||||
#define count_leading_zeros(count, x) \
|
||||
do { \
|
||||
USItype __cbtmp; \
|
||||
__asm__ ("bsrl %1,%0" \
|
||||
: "=r" (__cbtmp) : "rm" ((USItype)(x))); \
|
||||
(count) = __cbtmp ^ 31; \
|
||||
} while (0)
|
||||
#define count_trailing_zeros(count, x) \
|
||||
__asm__ ("bsfl %1,%0" : "=r" (count) : "rm" ((USItype)(x)))
|
||||
#ifndef UMUL_TIME
|
||||
#define UMUL_TIME 40
|
||||
#endif
|
||||
@ -536,15 +497,6 @@ do { \
|
||||
"dI" ((USItype)(d))); \
|
||||
(r) = __rq.__i.__l; (q) = __rq.__i.__h; \
|
||||
} while (0)
|
||||
#define count_leading_zeros(count, x) \
|
||||
do { \
|
||||
USItype __cbtmp; \
|
||||
__asm__ ("scanbit %1,%0" \
|
||||
: "=r" (__cbtmp) \
|
||||
: "r" ((USItype)(x))); \
|
||||
(count) = __cbtmp ^ 31; \
|
||||
} while (0)
|
||||
#define COUNT_LEADING_ZEROS_0 (-32) /* sic */
|
||||
#if defined(__i960mx) /* what is the proper symbol to test??? */
|
||||
#define rshift_rhlc(r, h, l, c) \
|
||||
do { \
|
||||
@ -603,11 +555,6 @@ do { \
|
||||
: "0" ((USItype)(n0)), \
|
||||
"1" ((USItype)(n1)), \
|
||||
"dmi" ((USItype)(d)))
|
||||
#define count_leading_zeros(count, x) \
|
||||
__asm__ ("bfffo %1{%b2:%b2},%0" \
|
||||
: "=d" ((USItype)(count)) \
|
||||
: "od" ((USItype)(x)), "n" (0))
|
||||
#define COUNT_LEADING_ZEROS_0 32
|
||||
#else /* not mc68020 */
|
||||
#define umul_ppmm(xh, xl, a, b) \
|
||||
do { USItype __umul_tmp1, __umul_tmp2; \
|
||||
@ -664,15 +611,6 @@ do { USItype __umul_tmp1, __umul_tmp2; \
|
||||
"rJ" ((USItype)(bh)), \
|
||||
"rJ" ((USItype)(al)), \
|
||||
"rJ" ((USItype)(bl)))
|
||||
#define count_leading_zeros(count, x) \
|
||||
do { \
|
||||
USItype __cbtmp; \
|
||||
__asm__ ("ff1 %0,%1" \
|
||||
: "=r" (__cbtmp) \
|
||||
: "r" ((USItype)(x))); \
|
||||
(count) = __cbtmp ^ 31; \
|
||||
} while (0)
|
||||
#define COUNT_LEADING_ZEROS_0 63 /* sic */
|
||||
#if defined(__m88110__)
|
||||
#define umul_ppmm(wh, wl, u, v) \
|
||||
do { \
|
||||
@ -779,12 +717,6 @@ do { \
|
||||
: "0" (__xx.__ll), \
|
||||
"g" ((USItype)(d))); \
|
||||
(r) = __xx.__i.__l; (q) = __xx.__i.__h; })
|
||||
#define count_trailing_zeros(count, x) \
|
||||
do { \
|
||||
__asm__("ffsd %2,%0" \
|
||||
: "=r"((USItype) (count)) \
|
||||
: "0"((USItype) 0), "r"((USItype) (x))); \
|
||||
} while (0)
|
||||
#endif /* __ns32000__ */
|
||||
|
||||
/***************************************
|
||||
@ -855,11 +787,6 @@ do { \
|
||||
"rI" ((USItype)(al)), \
|
||||
"r" ((USItype)(bl))); \
|
||||
} while (0)
|
||||
#define count_leading_zeros(count, x) \
|
||||
__asm__ ("{cntlz|cntlzw} %0,%1" \
|
||||
: "=r" ((USItype)(count)) \
|
||||
: "r" ((USItype)(x)))
|
||||
#define COUNT_LEADING_ZEROS_0 32
|
||||
#if defined(_ARCH_PPC)
|
||||
#define umul_ppmm(ph, pl, m0, m1) \
|
||||
do { \
|
||||
@ -1001,19 +928,6 @@ do { \
|
||||
} while (0)
|
||||
#define UMUL_TIME 20
|
||||
#define UDIV_TIME 200
|
||||
#define count_leading_zeros(count, x) \
|
||||
do { \
|
||||
if ((x) >= 0x10000) \
|
||||
__asm__ ("clz %0,%1" \
|
||||
: "=r" ((USItype)(count)) \
|
||||
: "r" ((USItype)(x) >> 16)); \
|
||||
else { \
|
||||
__asm__ ("clz %0,%1" \
|
||||
: "=r" ((USItype)(count)) \
|
||||
: "r" ((USItype)(x))); \
|
||||
(count) += 16; \
|
||||
} \
|
||||
} while (0)
|
||||
#endif /* RT/ROMP */
|
||||
|
||||
/***************************************
|
||||
@ -1142,13 +1056,6 @@ do { \
|
||||
"rI" ((USItype)(d)) \
|
||||
: "%g1" __AND_CLOBBER_CC)
|
||||
#define UDIV_TIME 37
|
||||
#define count_leading_zeros(count, x) \
|
||||
__asm__ ("scan %1,0,%0" \
|
||||
: "=r" ((USItype)(x)) \
|
||||
: "r" ((USItype)(count)))
|
||||
/* Early sparclites return 63 for an argument of 0, but they warn that future
|
||||
implementations might change this. Therefore, leave COUNT_LEADING_ZEROS_0
|
||||
undefined. */
|
||||
#endif /* __sparclite__ */
|
||||
#endif /* __sparc_v8__ */
|
||||
/* Default to sparc v7 versions of umul_ppmm and udiv_qrnnd. */
|
||||
@ -1454,47 +1361,6 @@ do { \
|
||||
#define udiv_qrnnd __udiv_qrnnd_c
|
||||
#endif
|
||||
|
||||
#undef count_leading_zeros
|
||||
#if !defined(count_leading_zeros)
|
||||
extern
|
||||
#ifdef __STDC__
|
||||
const
|
||||
#endif
|
||||
unsigned char __clz_tab[];
|
||||
#define count_leading_zeros(count, x) \
|
||||
do { \
|
||||
UWtype __xr = (x); \
|
||||
UWtype __a; \
|
||||
\
|
||||
if (W_TYPE_SIZE <= 32) { \
|
||||
__a = __xr < ((UWtype) 1 << 2*__BITS4) \
|
||||
? (__xr < ((UWtype) 1 << __BITS4) ? 0 : __BITS4) \
|
||||
: (__xr < ((UWtype) 1 << 3*__BITS4) ? 2*__BITS4 : 3*__BITS4); \
|
||||
} \
|
||||
else { \
|
||||
for (__a = W_TYPE_SIZE - 8; __a > 0; __a -= 8) \
|
||||
if (((__xr >> __a) & 0xff) != 0) \
|
||||
break; \
|
||||
} \
|
||||
\
|
||||
(count) = W_TYPE_SIZE - (__clz_tab[__xr >> __a] + __a); \
|
||||
} while (0)
|
||||
/* This version gives a well-defined value for zero. */
|
||||
#define COUNT_LEADING_ZEROS_0 W_TYPE_SIZE
|
||||
#endif
|
||||
|
||||
#if !defined(count_trailing_zeros)
|
||||
/* Define count_trailing_zeros using count_leading_zeros. The latter might be
|
||||
defined in asm, but if it is not, the C version above is good enough. */
|
||||
#define count_trailing_zeros(count, x) \
|
||||
do { \
|
||||
UWtype __ctz_x = (x); \
|
||||
UWtype __ctz_c; \
|
||||
count_leading_zeros(__ctz_c, __ctz_x & -__ctz_x); \
|
||||
(count) = W_TYPE_SIZE - 1 - __ctz_c; \
|
||||
} while (0)
|
||||
#endif
|
||||
|
||||
#ifndef UDIV_NEEDS_NORMALIZATION
|
||||
#define UDIV_NEEDS_NORMALIZATION 0
|
||||
#endif
|
||||
|
||||
@ -45,7 +45,7 @@ unsigned mpi_get_nbits(MPI a)
|
||||
if (a->nlimbs) {
|
||||
mpi_limb_t alimb = a->d[a->nlimbs - 1];
|
||||
if (alimb)
|
||||
count_leading_zeros(n, alimb);
|
||||
n = count_leading_zeros(alimb);
|
||||
else
|
||||
n = BITS_PER_MPI_LIMB;
|
||||
n = BITS_PER_MPI_LIMB - n + (a->nlimbs - 1) * BITS_PER_MPI_LIMB;
|
||||
|
||||
@ -77,7 +77,7 @@ int mpi_powm(MPI res, MPI base, MPI exp, MPI mod)
|
||||
mp = mp_marker = mpi_alloc_limb_space(msize);
|
||||
if (!mp)
|
||||
goto enomem;
|
||||
count_leading_zeros(mod_shift_cnt, mod->d[msize - 1]);
|
||||
mod_shift_cnt = count_leading_zeros(mod->d[msize - 1]);
|
||||
if (mod_shift_cnt)
|
||||
mpihelp_lshift(mp, mod->d, msize, mod_shift_cnt);
|
||||
else
|
||||
@ -169,7 +169,7 @@ int mpi_powm(MPI res, MPI base, MPI exp, MPI mod)
|
||||
|
||||
i = esize - 1;
|
||||
e = ep[i];
|
||||
count_leading_zeros(c, e);
|
||||
c = count_leading_zeros(e);
|
||||
e = (e << c) << 1; /* shift the exp bits to the left, lose msb */
|
||||
c = BITS_PER_MPI_LIMB - 1 - c;
|
||||
|
||||
|
||||
Loading…
Reference in New Issue
Block a user