mirror of
https://github.com/torvalds/linux.git
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3d0d14f983
lindent these files:
errors lines of code errors/KLOC
arch/x86/math-emu/ 2236 9424 237.2
arch/x86/math-emu/ 128 8706 14.7
no other changes. No code changed:
text data bss dec hex filename
5589802 612739 3833856 10036397 9924ad vmlinux.before
5589802 612739 3833856 10036397 9924ad vmlinux.after
the intent of this patch is to ease the automated tracking of kernel
code quality - it's just much easier for us to maintain it if every file
in arch/x86 is supposed to be clean.
NOTE: it is a known problem of lindent that it causes some style damage
of its own, but it's a safe tool (well, except for the gcc array range
initializers extension), so we did the bulk of the changes via lindent,
and did the manual fixups in a followup patch.
the resulting math-emu code has been tested by Thomas Gleixner on a real
386 DX CPU as well, and it works fine.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
146 lines
4.4 KiB
C
146 lines
4.4 KiB
C
/*---------------------------------------------------------------------------+
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| poly_2xm1.c |
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| Function to compute 2^x-1 by a polynomial approximation. |
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| Copyright (C) 1992,1993,1994,1997 |
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| W. Metzenthen, 22 Parker St, Ormond, Vic 3163, Australia |
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| E-mail billm@suburbia.net |
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+---------------------------------------------------------------------------*/
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#include "exception.h"
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#include "reg_constant.h"
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#include "fpu_emu.h"
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#include "fpu_system.h"
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#include "control_w.h"
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#include "poly.h"
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#define HIPOWER 11
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static const unsigned long long lterms[HIPOWER] = {
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0x0000000000000000LL, /* This term done separately as 12 bytes */
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0xf5fdeffc162c7543LL,
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0x1c6b08d704a0bfa6LL,
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0x0276556df749cc21LL,
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0x002bb0ffcf14f6b8LL,
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0x0002861225ef751cLL,
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0x00001ffcbfcd5422LL,
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0x00000162c005d5f1LL,
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0x0000000da96ccb1bLL,
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0x0000000078d1b897LL,
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0x000000000422b029LL
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};
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static const Xsig hiterm = MK_XSIG(0xb17217f7, 0xd1cf79ab, 0xc8a39194);
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/* Four slices: 0.0 : 0.25 : 0.50 : 0.75 : 1.0,
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These numbers are 2^(1/4), 2^(1/2), and 2^(3/4)
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*/
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static const Xsig shiftterm0 = MK_XSIG(0, 0, 0);
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static const Xsig shiftterm1 = MK_XSIG(0x9837f051, 0x8db8a96f, 0x46ad2318);
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static const Xsig shiftterm2 = MK_XSIG(0xb504f333, 0xf9de6484, 0x597d89b3);
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static const Xsig shiftterm3 = MK_XSIG(0xd744fcca, 0xd69d6af4, 0x39a68bb9);
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static const Xsig *shiftterm[] = { &shiftterm0, &shiftterm1,
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&shiftterm2, &shiftterm3
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};
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/*--- poly_2xm1() -----------------------------------------------------------+
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| Requires st(0) which is TAG_Valid and < 1. |
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+---------------------------------------------------------------------------*/
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int poly_2xm1(u_char sign, FPU_REG * arg, FPU_REG * result)
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{
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long int exponent, shift;
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unsigned long long Xll;
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Xsig accumulator, Denom, argSignif;
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u_char tag;
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exponent = exponent16(arg);
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#ifdef PARANOID
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if (exponent >= 0) { /* Don't want a |number| >= 1.0 */
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/* Number negative, too large, or not Valid. */
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EXCEPTION(EX_INTERNAL | 0x127);
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return 1;
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}
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#endif /* PARANOID */
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argSignif.lsw = 0;
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XSIG_LL(argSignif) = Xll = significand(arg);
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if (exponent == -1) {
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shift = (argSignif.msw & 0x40000000) ? 3 : 2;
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/* subtract 0.5 or 0.75 */
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exponent -= 2;
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XSIG_LL(argSignif) <<= 2;
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Xll <<= 2;
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} else if (exponent == -2) {
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shift = 1;
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/* subtract 0.25 */
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exponent--;
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XSIG_LL(argSignif) <<= 1;
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Xll <<= 1;
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} else
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shift = 0;
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if (exponent < -2) {
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/* Shift the argument right by the required places. */
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if (FPU_shrx(&Xll, -2 - exponent) >= 0x80000000U)
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Xll++; /* round up */
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}
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accumulator.lsw = accumulator.midw = accumulator.msw = 0;
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polynomial_Xsig(&accumulator, &Xll, lterms, HIPOWER - 1);
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mul_Xsig_Xsig(&accumulator, &argSignif);
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shr_Xsig(&accumulator, 3);
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mul_Xsig_Xsig(&argSignif, &hiterm); /* The leading term */
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add_two_Xsig(&accumulator, &argSignif, &exponent);
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if (shift) {
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/* The argument is large, use the identity:
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f(x+a) = f(a) * (f(x) + 1) - 1;
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*/
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shr_Xsig(&accumulator, -exponent);
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accumulator.msw |= 0x80000000; /* add 1.0 */
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mul_Xsig_Xsig(&accumulator, shiftterm[shift]);
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accumulator.msw &= 0x3fffffff; /* subtract 1.0 */
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exponent = 1;
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}
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if (sign != SIGN_POS) {
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/* The argument is negative, use the identity:
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f(-x) = -f(x) / (1 + f(x))
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*/
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Denom.lsw = accumulator.lsw;
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XSIG_LL(Denom) = XSIG_LL(accumulator);
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if (exponent < 0)
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shr_Xsig(&Denom, -exponent);
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else if (exponent > 0) {
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/* exponent must be 1 here */
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XSIG_LL(Denom) <<= 1;
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if (Denom.lsw & 0x80000000)
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XSIG_LL(Denom) |= 1;
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(Denom.lsw) <<= 1;
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}
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Denom.msw |= 0x80000000; /* add 1.0 */
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div_Xsig(&accumulator, &Denom, &accumulator);
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}
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/* Convert to 64 bit signed-compatible */
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exponent += round_Xsig(&accumulator);
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result = &st(0);
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significand(result) = XSIG_LL(accumulator);
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setexponent16(result, exponent);
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tag = FPU_round(result, 1, 0, FULL_PRECISION, sign);
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setsign(result, sign);
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FPU_settag0(tag);
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return 0;
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}
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