Initial import

1 files changed, 244 insertions, 0 deletions

diff --git a/arch/x86/math-emu/poly_l2.c b/arch/x86/math-emu/poly_l2.c
new file mode 100644
index 000000000..8e2ff4b28
--- /dev/null
+++ b/arch/x86/math-emu/poly_l2.c
@@ -0,0 +1,244 @@
+/*---------------------------------------------------------------------------+
+ |  poly_l2.c                                                                |
+ |                                                                           |
+ | Compute the base 2 log of a FPU_REG, using a polynomial approximation.    |
+ |                                                                           |
+ | Copyright (C) 1992,1993,1994,1997                                         |
+ |                  W. Metzenthen, 22 Parker St, Ormond, Vic 3163, Australia |
+ |                  E-mail   billm@suburbia.net                              |
+ |                                                                           |
+ |                                                                           |
+ +---------------------------------------------------------------------------*/
+
+#include "exception.h"
+#include "reg_constant.h"
+#include "fpu_emu.h"
+#include "fpu_system.h"
+#include "control_w.h"
+#include "poly.h"
+
+static void log2_kernel(FPU_REG const *arg, u_char argsign,
+			Xsig * accum_result, long int *expon);
+
+/*--- poly_l2() -------------------------------------------------------------+
+ |   Base 2 logarithm by a polynomial approximation.                         |
+ +---------------------------------------------------------------------------*/
+void poly_l2(FPU_REG *st0_ptr, FPU_REG *st1_ptr, u_char st1_sign)
+{
+	long int exponent, expon, expon_expon;
+	Xsig accumulator, expon_accum, yaccum;
+	u_char sign, argsign;
+	FPU_REG x;
+	int tag;
+
+	exponent = exponent16(st0_ptr);
+
+	/* From st0_ptr, make a number > sqrt(2)/2 and < sqrt(2) */
+	if (st0_ptr->sigh > (unsigned)0xb504f334) {
+		/* Treat as  sqrt(2)/2 < st0_ptr < 1 */
+		significand(&x) = -significand(st0_ptr);
+		setexponent16(&x, -1);
+		exponent++;
+		argsign = SIGN_NEG;
+	} else {
+		/* Treat as  1 <= st0_ptr < sqrt(2) */
+		x.sigh = st0_ptr->sigh - 0x80000000;
+		x.sigl = st0_ptr->sigl;
+		setexponent16(&x, 0);
+		argsign = SIGN_POS;
+	}
+	tag = FPU_normalize_nuo(&x);
+
+	if (tag == TAG_Zero) {
+		expon = 0;
+		accumulator.msw = accumulator.midw = accumulator.lsw = 0;
+	} else {
+		log2_kernel(&x, argsign, &accumulator, &expon);
+	}
+
+	if (exponent < 0) {
+		sign = SIGN_NEG;
+		exponent = -exponent;
+	} else
+		sign = SIGN_POS;
+	expon_accum.msw = exponent;
+	expon_accum.midw = expon_accum.lsw = 0;
+	if (exponent) {
+		expon_expon = 31 + norm_Xsig(&expon_accum);
+		shr_Xsig(&accumulator, expon_expon - expon);
+
+		if (sign ^ argsign)
+			negate_Xsig(&accumulator);
+		add_Xsig_Xsig(&accumulator, &expon_accum);
+	} else {
+		expon_expon = expon;
+		sign = argsign;
+	}
+
+	yaccum.lsw = 0;
+	XSIG_LL(yaccum) = significand(st1_ptr);
+	mul_Xsig_Xsig(&accumulator, &yaccum);
+
+	expon_expon += round_Xsig(&accumulator);
+
+	if (accumulator.msw == 0) {
+		FPU_copy_to_reg1(&CONST_Z, TAG_Zero);
+		return;
+	}
+
+	significand(st1_ptr) = XSIG_LL(accumulator);
+	setexponent16(st1_ptr, expon_expon + exponent16(st1_ptr) + 1);
+
+	tag = FPU_round(st1_ptr, 1, 0, FULL_PRECISION, sign ^ st1_sign);
+	FPU_settagi(1, tag);
+
+	set_precision_flag_up();	/* 80486 appears to always do this */
+
+	return;
+
+}
+
+/*--- poly_l2p1() -----------------------------------------------------------+
+ |   Base 2 logarithm by a polynomial approximation.                         |
+ |   log2(x+1)                                                               |
+ +---------------------------------------------------------------------------*/
+int poly_l2p1(u_char sign0, u_char sign1,
+	      FPU_REG * st0_ptr, FPU_REG * st1_ptr, FPU_REG * dest)
+{
+	u_char tag;
+	long int exponent;
+	Xsig accumulator, yaccum;
+
+	if (exponent16(st0_ptr) < 0) {
+		log2_kernel(st0_ptr, sign0, &accumulator, &exponent);
+
+		yaccum.lsw = 0;
+		XSIG_LL(yaccum) = significand(st1_ptr);
+		mul_Xsig_Xsig(&accumulator, &yaccum);
+
+		exponent += round_Xsig(&accumulator);
+
+		exponent += exponent16(st1_ptr) + 1;
+		if (exponent < EXP_WAY_UNDER)
+			exponent = EXP_WAY_UNDER;
+
+		significand(dest) = XSIG_LL(accumulator);
+		setexponent16(dest, exponent);
+
+		tag = FPU_round(dest, 1, 0, FULL_PRECISION, sign0 ^ sign1);
+		FPU_settagi(1, tag);
+
+		if (tag == TAG_Valid)
+			set_precision_flag_up();	/* 80486 appears to always do this */
+	} else {
+		/* The magnitude of st0_ptr is far too large. */
+
+		if (sign0 != SIGN_POS) {
+			/* Trying to get the log of a negative number. */
+#ifdef PECULIAR_486		/* Stupid 80486 doesn't worry about log(negative). */
+			changesign(st1_ptr);
+#else
+			if (arith_invalid(1) < 0)
+				return 1;
+#endif /* PECULIAR_486 */
+		}
+
+		/* 80486 appears to do this */
+		if (sign0 == SIGN_NEG)
+			set_precision_flag_down();
+		else
+			set_precision_flag_up();
+	}
+
+	if (exponent(dest) <= EXP_UNDER)
+		EXCEPTION(EX_Underflow);
+
+	return 0;
+
+}
+
+#undef HIPOWER
+#define	HIPOWER	10
+static const unsigned long long logterms[HIPOWER] = {
+	0x2a8eca5705fc2ef0LL,
+	0xf6384ee1d01febceLL,
+	0x093bb62877cdf642LL,
+	0x006985d8a9ec439bLL,
+	0x0005212c4f55a9c8LL,
+	0x00004326a16927f0LL,
+	0x0000038d1d80a0e7LL,
+	0x0000003141cc80c6LL,
+	0x00000002b1668c9fLL,
+	0x000000002c7a46aaLL
+};
+
+static const unsigned long leadterm = 0xb8000000;
+
+/*--- log2_kernel() ---------------------------------------------------------+
+ |   Base 2 logarithm by a polynomial approximation.                         |
+ |   log2(x+1)                                                               |
+ +---------------------------------------------------------------------------*/
+static void log2_kernel(FPU_REG const *arg, u_char argsign, Xsig *accum_result,
+			long int *expon)
+{
+	long int exponent, adj;
+	unsigned long long Xsq;
+	Xsig accumulator, Numer, Denom, argSignif, arg_signif;
+
+	exponent = exponent16(arg);
+	Numer.lsw = Denom.lsw = 0;
+	XSIG_LL(Numer) = XSIG_LL(Denom) = significand(arg);
+	if (argsign == SIGN_POS) {
+		shr_Xsig(&Denom, 2 - (1 + exponent));
+		Denom.msw |= 0x80000000;
+		div_Xsig(&Numer, &Denom, &argSignif);
+	} else {
+		shr_Xsig(&Denom, 1 - (1 + exponent));
+		negate_Xsig(&Denom);
+		if (Denom.msw & 0x80000000) {
+			div_Xsig(&Numer, &Denom, &argSignif);
+			exponent++;
+		} else {
+			/* Denom must be 1.0 */
+			argSignif.lsw = Numer.lsw;
+			argSignif.midw = Numer.midw;
+			argSignif.msw = Numer.msw;
+		}
+	}
+
+#ifndef PECULIAR_486
+	/* Should check here that  |local_arg|  is within the valid range */
+	if (exponent >= -2) {
+		if ((exponent > -2) || (argSignif.msw > (unsigned)0xafb0ccc0)) {
+			/* The argument is too large */
+		}
+	}
+#endif /* PECULIAR_486 */
+
+	arg_signif.lsw = argSignif.lsw;
+	XSIG_LL(arg_signif) = XSIG_LL(argSignif);
+	adj = norm_Xsig(&argSignif);
+	accumulator.lsw = argSignif.lsw;
+	XSIG_LL(accumulator) = XSIG_LL(argSignif);
+	mul_Xsig_Xsig(&accumulator, &accumulator);
+	shr_Xsig(&accumulator, 2 * (-1 - (1 + exponent + adj)));
+	Xsq = XSIG_LL(accumulator);
+	if (accumulator.lsw & 0x80000000)
+		Xsq++;
+
+	accumulator.msw = accumulator.midw = accumulator.lsw = 0;
+	/* Do the basic fixed point polynomial evaluation */
+	polynomial_Xsig(&accumulator, &Xsq, logterms, HIPOWER - 1);
+
+	mul_Xsig_Xsig(&accumulator, &argSignif);
+	shr_Xsig(&accumulator, 6 - adj);
+
+	mul32_Xsig(&arg_signif, leadterm);
+	add_two_Xsig(&accumulator, &arg_signif, &exponent);
+
+	*expon = exponent + 1;
+	accum_result->lsw = accumulator.lsw;
+	accum_result->midw = accumulator.midw;
+	accum_result->msw = accumulator.msw;
+
+}