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>
213 lines
6.8 KiB
C
213 lines
6.8 KiB
C
/*---------------------------------------------------------------------------+
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| poly_tan.c |
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| Compute the tan of a FPU_REG, using a polynomial approximation. |
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| Copyright (C) 1992,1993,1994,1997,1999 |
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| W. Metzenthen, 22 Parker St, Ormond, Vic 3163, |
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| Australia. E-mail billm@melbpc.org.au |
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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 HiPOWERop 3 /* odd poly, positive terms */
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static const unsigned long long oddplterm[HiPOWERop] = {
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0x0000000000000000LL,
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0x0051a1cf08fca228LL,
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0x0000000071284ff7LL
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};
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#define HiPOWERon 2 /* odd poly, negative terms */
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static const unsigned long long oddnegterm[HiPOWERon] = {
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0x1291a9a184244e80LL,
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0x0000583245819c21LL
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};
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#define HiPOWERep 2 /* even poly, positive terms */
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static const unsigned long long evenplterm[HiPOWERep] = {
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0x0e848884b539e888LL,
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0x00003c7f18b887daLL
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};
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#define HiPOWERen 2 /* even poly, negative terms */
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static const unsigned long long evennegterm[HiPOWERen] = {
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0xf1f0200fd51569ccLL,
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0x003afb46105c4432LL
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};
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static const unsigned long long twothirds = 0xaaaaaaaaaaaaaaabLL;
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/*--- poly_tan() ------------------------------------------------------------+
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+---------------------------------------------------------------------------*/
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void poly_tan(FPU_REG * st0_ptr)
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{
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long int exponent;
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int invert;
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Xsig argSq, argSqSq, accumulatoro, accumulatore, accum,
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argSignif, fix_up;
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unsigned long adj;
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exponent = exponent(st0_ptr);
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#ifdef PARANOID
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if (signnegative(st0_ptr)) { /* Can't hack a number < 0.0 */
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arith_invalid(0);
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return;
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} /* Need a positive number */
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#endif /* PARANOID */
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/* Split the problem into two domains, smaller and larger than pi/4 */
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if ((exponent == 0)
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|| ((exponent == -1) && (st0_ptr->sigh > 0xc90fdaa2))) {
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/* The argument is greater than (approx) pi/4 */
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invert = 1;
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accum.lsw = 0;
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XSIG_LL(accum) = significand(st0_ptr);
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if (exponent == 0) {
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/* The argument is >= 1.0 */
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/* Put the binary point at the left. */
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XSIG_LL(accum) <<= 1;
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}
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/* pi/2 in hex is: 1.921fb54442d18469 898CC51701B839A2 52049C1 */
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XSIG_LL(accum) = 0x921fb54442d18469LL - XSIG_LL(accum);
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/* This is a special case which arises due to rounding. */
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if (XSIG_LL(accum) == 0xffffffffffffffffLL) {
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FPU_settag0(TAG_Valid);
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significand(st0_ptr) = 0x8a51e04daabda360LL;
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setexponent16(st0_ptr,
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(0x41 + EXTENDED_Ebias) | SIGN_Negative);
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return;
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}
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argSignif.lsw = accum.lsw;
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XSIG_LL(argSignif) = XSIG_LL(accum);
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exponent = -1 + norm_Xsig(&argSignif);
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} else {
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invert = 0;
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argSignif.lsw = 0;
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XSIG_LL(accum) = XSIG_LL(argSignif) = significand(st0_ptr);
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if (exponent < -1) {
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/* shift the argument right by the required places */
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if (FPU_shrx(&XSIG_LL(accum), -1 - exponent) >=
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0x80000000U)
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XSIG_LL(accum)++; /* round up */
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}
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}
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XSIG_LL(argSq) = XSIG_LL(accum);
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argSq.lsw = accum.lsw;
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mul_Xsig_Xsig(&argSq, &argSq);
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XSIG_LL(argSqSq) = XSIG_LL(argSq);
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argSqSq.lsw = argSq.lsw;
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mul_Xsig_Xsig(&argSqSq, &argSqSq);
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/* Compute the negative terms for the numerator polynomial */
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accumulatoro.msw = accumulatoro.midw = accumulatoro.lsw = 0;
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polynomial_Xsig(&accumulatoro, &XSIG_LL(argSqSq), oddnegterm,
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HiPOWERon - 1);
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mul_Xsig_Xsig(&accumulatoro, &argSq);
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negate_Xsig(&accumulatoro);
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/* Add the positive terms */
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polynomial_Xsig(&accumulatoro, &XSIG_LL(argSqSq), oddplterm,
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HiPOWERop - 1);
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/* Compute the positive terms for the denominator polynomial */
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accumulatore.msw = accumulatore.midw = accumulatore.lsw = 0;
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polynomial_Xsig(&accumulatore, &XSIG_LL(argSqSq), evenplterm,
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HiPOWERep - 1);
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mul_Xsig_Xsig(&accumulatore, &argSq);
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negate_Xsig(&accumulatore);
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/* Add the negative terms */
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polynomial_Xsig(&accumulatore, &XSIG_LL(argSqSq), evennegterm,
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HiPOWERen - 1);
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/* Multiply by arg^2 */
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mul64_Xsig(&accumulatore, &XSIG_LL(argSignif));
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mul64_Xsig(&accumulatore, &XSIG_LL(argSignif));
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/* de-normalize and divide by 2 */
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shr_Xsig(&accumulatore, -2 * (1 + exponent) + 1);
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negate_Xsig(&accumulatore); /* This does 1 - accumulator */
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/* Now find the ratio. */
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if (accumulatore.msw == 0) {
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/* accumulatoro must contain 1.0 here, (actually, 0) but it
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really doesn't matter what value we use because it will
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have negligible effect in later calculations
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*/
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XSIG_LL(accum) = 0x8000000000000000LL;
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accum.lsw = 0;
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} else {
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div_Xsig(&accumulatoro, &accumulatore, &accum);
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}
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/* Multiply by 1/3 * arg^3 */
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mul64_Xsig(&accum, &XSIG_LL(argSignif));
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mul64_Xsig(&accum, &XSIG_LL(argSignif));
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mul64_Xsig(&accum, &XSIG_LL(argSignif));
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mul64_Xsig(&accum, &twothirds);
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shr_Xsig(&accum, -2 * (exponent + 1));
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/* tan(arg) = arg + accum */
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add_two_Xsig(&accum, &argSignif, &exponent);
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if (invert) {
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/* We now have the value of tan(pi_2 - arg) where pi_2 is an
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approximation for pi/2
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*/
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/* The next step is to fix the answer to compensate for the
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error due to the approximation used for pi/2
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*/
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/* This is (approx) delta, the error in our approx for pi/2
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(see above). It has an exponent of -65
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*/
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XSIG_LL(fix_up) = 0x898cc51701b839a2LL;
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fix_up.lsw = 0;
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if (exponent == 0)
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adj = 0xffffffff; /* We want approx 1.0 here, but
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this is close enough. */
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else if (exponent > -30) {
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adj = accum.msw >> -(exponent + 1); /* tan */
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adj = mul_32_32(adj, adj); /* tan^2 */
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} else
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adj = 0;
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adj = mul_32_32(0x898cc517, adj); /* delta * tan^2 */
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fix_up.msw += adj;
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if (!(fix_up.msw & 0x80000000)) { /* did fix_up overflow ? */
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/* Yes, we need to add an msb */
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shr_Xsig(&fix_up, 1);
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fix_up.msw |= 0x80000000;
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shr_Xsig(&fix_up, 64 + exponent);
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} else
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shr_Xsig(&fix_up, 65 + exponent);
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add_two_Xsig(&accum, &fix_up, &exponent);
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/* accum now contains tan(pi/2 - arg).
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Use tan(arg) = 1.0 / tan(pi/2 - arg)
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*/
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accumulatoro.lsw = accumulatoro.midw = 0;
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accumulatoro.msw = 0x80000000;
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div_Xsig(&accumulatoro, &accum, &accum);
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exponent = -exponent - 1;
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}
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/* Transfer the result */
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round_Xsig(&accum);
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FPU_settag0(TAG_Valid);
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significand(st0_ptr) = XSIG_LL(accum);
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setexponent16(st0_ptr, exponent + EXTENDED_Ebias); /* Result is positive. */
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}
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