Initial import

1 files changed, 212 insertions, 0 deletions

diff --git a/arch/x86/math-emu/poly_tan.c b/arch/x86/math-emu/poly_tan.c
new file mode 100644
index 000000000..1875763e0
--- /dev/null
+++ b/arch/x86/math-emu/poly_tan.c
@@ -0,0 +1,212 @@
+/*---------------------------------------------------------------------------+
+ |  poly_tan.c                                                               |
+ |                                                                           |
+ | Compute the tan of a FPU_REG, using a polynomial approximation.           |
+ |                                                                           |
+ | Copyright (C) 1992,1993,1994,1997,1999                                    |
+ |                       W. Metzenthen, 22 Parker St, Ormond, Vic 3163,      |
+ |                       Australia.  E-mail   billm@melbpc.org.au            |
+ |                                                                           |
+ |                                                                           |
+ +---------------------------------------------------------------------------*/
+
+#include "exception.h"
+#include "reg_constant.h"
+#include "fpu_emu.h"
+#include "fpu_system.h"
+#include "control_w.h"
+#include "poly.h"
+
+#define	HiPOWERop	3	/* odd poly, positive terms */
+static const unsigned long long oddplterm[HiPOWERop] = {
+	0x0000000000000000LL,
+	0x0051a1cf08fca228LL,
+	0x0000000071284ff7LL
+};
+
+#define	HiPOWERon	2	/* odd poly, negative terms */
+static const unsigned long long oddnegterm[HiPOWERon] = {
+	0x1291a9a184244e80LL,
+	0x0000583245819c21LL
+};
+
+#define	HiPOWERep	2	/* even poly, positive terms */
+static const unsigned long long evenplterm[HiPOWERep] = {
+	0x0e848884b539e888LL,
+	0x00003c7f18b887daLL
+};
+
+#define	HiPOWERen	2	/* even poly, negative terms */
+static const unsigned long long evennegterm[HiPOWERen] = {
+	0xf1f0200fd51569ccLL,
+	0x003afb46105c4432LL
+};
+
+static const unsigned long long twothirds = 0xaaaaaaaaaaaaaaabLL;
+
+/*--- poly_tan() ------------------------------------------------------------+
+ |                                                                           |
+ +---------------------------------------------------------------------------*/
+void poly_tan(FPU_REG *st0_ptr)
+{
+	long int exponent;
+	int invert;
+	Xsig argSq, argSqSq, accumulatoro, accumulatore, accum,
+	    argSignif, fix_up;
+	unsigned long adj;
+
+	exponent = exponent(st0_ptr);
+
+#ifdef PARANOID
+	if (signnegative(st0_ptr)) {	/* Can't hack a number < 0.0 */
+		arith_invalid(0);
+		return;
+	}			/* Need a positive number */
+#endif /* PARANOID */
+
+	/* Split the problem into two domains, smaller and larger than pi/4 */
+	if ((exponent == 0)
+	    || ((exponent == -1) && (st0_ptr->sigh > 0xc90fdaa2))) {
+		/* The argument is greater than (approx) pi/4 */
+		invert = 1;
+		accum.lsw = 0;
+		XSIG_LL(accum) = significand(st0_ptr);
+
+		if (exponent == 0) {
+			/* The argument is >= 1.0 */
+			/* Put the binary point at the left. */
+			XSIG_LL(accum) <<= 1;
+		}
+		/* pi/2 in hex is: 1.921fb54442d18469 898CC51701B839A2 52049C1 */
+		XSIG_LL(accum) = 0x921fb54442d18469LL - XSIG_LL(accum);
+		/* This is a special case which arises due to rounding. */
+		if (XSIG_LL(accum) == 0xffffffffffffffffLL) {
+			FPU_settag0(TAG_Valid);
+			significand(st0_ptr) = 0x8a51e04daabda360LL;
+			setexponent16(st0_ptr,
+				      (0x41 + EXTENDED_Ebias) | SIGN_Negative);
+			return;
+		}
+
+		argSignif.lsw = accum.lsw;
+		XSIG_LL(argSignif) = XSIG_LL(accum);
+		exponent = -1 + norm_Xsig(&argSignif);
+	} else {
+		invert = 0;
+		argSignif.lsw = 0;
+		XSIG_LL(accum) = XSIG_LL(argSignif) = significand(st0_ptr);
+
+		if (exponent < -1) {
+			/* shift the argument right by the required places */
+			if (FPU_shrx(&XSIG_LL(accum), -1 - exponent) >=
+			    0x80000000U)
+				XSIG_LL(accum)++;	/* round up */
+		}
+	}
+
+	XSIG_LL(argSq) = XSIG_LL(accum);
+	argSq.lsw = accum.lsw;
+	mul_Xsig_Xsig(&argSq, &argSq);
+	XSIG_LL(argSqSq) = XSIG_LL(argSq);
+	argSqSq.lsw = argSq.lsw;
+	mul_Xsig_Xsig(&argSqSq, &argSqSq);
+
+	/* Compute the negative terms for the numerator polynomial */
+	accumulatoro.msw = accumulatoro.midw = accumulatoro.lsw = 0;
+	polynomial_Xsig(&accumulatoro, &XSIG_LL(argSqSq), oddnegterm,
+			HiPOWERon - 1);
+	mul_Xsig_Xsig(&accumulatoro, &argSq);
+	negate_Xsig(&accumulatoro);
+	/* Add the positive terms */
+	polynomial_Xsig(&accumulatoro, &XSIG_LL(argSqSq), oddplterm,
+			HiPOWERop - 1);
+
+	/* Compute the positive terms for the denominator polynomial */
+	accumulatore.msw = accumulatore.midw = accumulatore.lsw = 0;
+	polynomial_Xsig(&accumulatore, &XSIG_LL(argSqSq), evenplterm,
+			HiPOWERep - 1);
+	mul_Xsig_Xsig(&accumulatore, &argSq);
+	negate_Xsig(&accumulatore);
+	/* Add the negative terms */
+	polynomial_Xsig(&accumulatore, &XSIG_LL(argSqSq), evennegterm,
+			HiPOWERen - 1);
+	/* Multiply by arg^2 */
+	mul64_Xsig(&accumulatore, &XSIG_LL(argSignif));
+	mul64_Xsig(&accumulatore, &XSIG_LL(argSignif));
+	/* de-normalize and divide by 2 */
+	shr_Xsig(&accumulatore, -2 * (1 + exponent) + 1);
+	negate_Xsig(&accumulatore);	/* This does 1 - accumulator */
+
+	/* Now find the ratio. */
+	if (accumulatore.msw == 0) {
+		/* accumulatoro must contain 1.0 here, (actually, 0) but it
+		   really doesn't matter what value we use because it will
+		   have negligible effect in later calculations
+		 */
+		XSIG_LL(accum) = 0x8000000000000000LL;
+		accum.lsw = 0;
+	} else {
+		div_Xsig(&accumulatoro, &accumulatore, &accum);
+	}
+
+	/* Multiply by 1/3 * arg^3 */
+	mul64_Xsig(&accum, &XSIG_LL(argSignif));
+	mul64_Xsig(&accum, &XSIG_LL(argSignif));
+	mul64_Xsig(&accum, &XSIG_LL(argSignif));
+	mul64_Xsig(&accum, &twothirds);
+	shr_Xsig(&accum, -2 * (exponent + 1));
+
+	/* tan(arg) = arg + accum */
+	add_two_Xsig(&accum, &argSignif, &exponent);
+
+	if (invert) {
+		/* We now have the value of tan(pi_2 - arg) where pi_2 is an
+		   approximation for pi/2
+		 */
+		/* The next step is to fix the answer to compensate for the
+		   error due to the approximation used for pi/2
+		 */
+
+		/* This is (approx) delta, the error in our approx for pi/2
+		   (see above). It has an exponent of -65
+		 */
+		XSIG_LL(fix_up) = 0x898cc51701b839a2LL;
+		fix_up.lsw = 0;
+
+		if (exponent == 0)
+			adj = 0xffffffff;	/* We want approx 1.0 here, but
+						   this is close enough. */
+		else if (exponent > -30) {
+			adj = accum.msw >> -(exponent + 1);	/* tan */
+			adj = mul_32_32(adj, adj);	/* tan^2 */
+		} else
+			adj = 0;
+		adj = mul_32_32(0x898cc517, adj);	/* delta * tan^2 */
+
+		fix_up.msw += adj;
+		if (!(fix_up.msw & 0x80000000)) {	/* did fix_up overflow ? */
+			/* Yes, we need to add an msb */
+			shr_Xsig(&fix_up, 1);
+			fix_up.msw |= 0x80000000;
+			shr_Xsig(&fix_up, 64 + exponent);
+		} else
+			shr_Xsig(&fix_up, 65 + exponent);
+
+		add_two_Xsig(&accum, &fix_up, &exponent);
+
+		/* accum now contains tan(pi/2 - arg).
+		   Use tan(arg) = 1.0 / tan(pi/2 - arg)
+		 */
+		accumulatoro.lsw = accumulatoro.midw = 0;
+		accumulatoro.msw = 0x80000000;
+		div_Xsig(&accumulatoro, &accum, &accum);
+		exponent = -exponent - 1;
+	}
+
+	/* Transfer the result */
+	round_Xsig(&accum);
+	FPU_settag0(TAG_Valid);
+	significand(st0_ptr) = XSIG_LL(accum);
+	setexponent16(st0_ptr, exponent + EXTENDED_Ebias);	/* Result is positive. */
+
+}