Import netbsd's fpu handling (modified to be separate from sparc); this is

for paranoia's sake (don't want to break sparc32 while hacking on it).
Real work by art.

1 files changed, 535 insertions, 0 deletions

diff --git a/sys/arch/sparc64/fpu/fpu_implode.c b/sys/arch/sparc64/fpu/fpu_implode.c
new file mode 100644
index 00000000000..1b7522b0637
--- /dev/null
+++ b/sys/arch/sparc64/fpu/fpu_implode.c
@@ -0,0 +1,535 @@
+/*	$OpenBSD: fpu_implode.c,v 1.1 2001/09/08 22:33:51 jason Exp $	*/
+/*	$NetBSD: fpu_implode.c,v 1.7 2000/08/03 18:32:08 eeh Exp $ */
+
+/*
+ * Copyright (c) 1992, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * This software was developed by the Computer Systems Engineering group
+ * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
+ * contributed to Berkeley.
+ *
+ * All advertising materials mentioning features or use of this software
+ * must display the following acknowledgement:
+ *	This product includes software developed by the University of
+ *	California, Lawrence Berkeley Laboratory.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *	This product includes software developed by the University of
+ *	California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ *	@(#)fpu_implode.c	8.1 (Berkeley) 6/11/93
+ */
+
+/*
+ * FPU subroutines: `implode' internal format numbers into the machine's
+ * `packed binary' format.
+ */
+
+#include <sys/types.h>
+#include <sys/systm.h>
+
+#include <machine/ieee.h>
+#include <machine/instr.h>
+#include <machine/reg.h>
+
+#include <sparc64/fpu/fpu_arith.h>
+#include <sparc64/fpu/fpu_emu.h>
+#include <sparc64/fpu/fpu_extern.h>
+
+static int round __P((register struct fpemu *, register struct fpn *));
+static int toinf __P((struct fpemu *, int));
+
+/*
+ * Round a number (algorithm from Motorola MC68882 manual, modified for
+ * our internal format).  Set inexact exception if rounding is required.
+ * Return true iff we rounded up.
+ *
+ * After rounding, we discard the guard and round bits by shifting right
+ * 2 bits (a la fpu_shr(), but we do not bother with fp->fp_sticky).
+ * This saves effort later.
+ *
+ * Note that we may leave the value 2.0 in fp->fp_mant; it is the caller's
+ * responsibility to fix this if necessary.
+ */
+static int
+round(register struct fpemu *fe, register struct fpn *fp)
+{
+	register u_int m0, m1, m2, m3;
+	register int gr, s;
+
+	m0 = fp->fp_mant[0];
+	m1 = fp->fp_mant[1];
+	m2 = fp->fp_mant[2];
+	m3 = fp->fp_mant[3];
+	gr = m3 & 3;
+	s = fp->fp_sticky;
+
+	/* mant >>= FP_NG */
+	m3 = (m3 >> FP_NG) | (m2 << (32 - FP_NG));
+	m2 = (m2 >> FP_NG) | (m1 << (32 - FP_NG));
+	m1 = (m1 >> FP_NG) | (m0 << (32 - FP_NG));
+	m0 >>= FP_NG;
+
+	if ((gr | s) == 0)	/* result is exact: no rounding needed */
+		goto rounddown;
+
+	fe->fe_cx |= FSR_NX;	/* inexact */
+
+	/* Go to rounddown to round down; break to round up. */
+	switch ((fe->fe_fsr >> FSR_RD_SHIFT) & FSR_RD_MASK) {
+
+	case FSR_RD_RN:
+	default:
+		/*
+		 * Round only if guard is set (gr & 2).  If guard is set,
+		 * but round & sticky both clear, then we want to round
+		 * but have a tie, so round to even, i.e., add 1 iff odd.
+		 */
+		if ((gr & 2) == 0)
+			goto rounddown;
+		if ((gr & 1) || fp->fp_sticky || (m3 & 1))
+			break;
+		goto rounddown;
+
+	case FSR_RD_RZ:
+		/* Round towards zero, i.e., down. */
+		goto rounddown;
+
+	case FSR_RD_RM:
+		/* Round towards -Inf: up if negative, down if positive. */
+		if (fp->fp_sign)
+			break;
+		goto rounddown;
+
+	case FSR_RD_RP:
+		/* Round towards +Inf: up if positive, down otherwise. */
+		if (!fp->fp_sign)
+			break;
+		goto rounddown;
+	}
+
+	/* Bump low bit of mantissa, with carry. */
+	FPU_ADDS(m3, m3, 1);
+	FPU_ADDCS(m2, m2, 0);
+	FPU_ADDCS(m1, m1, 0);
+	FPU_ADDC(m0, m0, 0);
+	fp->fp_mant[0] = m0;
+	fp->fp_mant[1] = m1;
+	fp->fp_mant[2] = m2;
+	fp->fp_mant[3] = m3;
+	return (1);
+
+rounddown:
+	fp->fp_mant[0] = m0;
+	fp->fp_mant[1] = m1;
+	fp->fp_mant[2] = m2;
+	fp->fp_mant[3] = m3;
+	return (0);
+}
+
+/*
+ * For overflow: return true if overflow is to go to +/-Inf, according
+ * to the sign of the overflowing result.  If false, overflow is to go
+ * to the largest magnitude value instead.
+ */
+static int
+toinf(struct fpemu *fe, int sign)
+{
+	int inf;
+
+	/* look at rounding direction */
+	switch ((fe->fe_fsr >> FSR_RD_SHIFT) & FSR_RD_MASK) {
+
+	default:
+	case FSR_RD_RN:		/* the nearest value is always Inf */
+		inf = 1;
+		break;
+
+	case FSR_RD_RZ:		/* toward 0 => never towards Inf */
+		inf = 0;
+		break;
+
+	case FSR_RD_RP:		/* toward +Inf iff positive */
+		inf = sign == 0;
+		break;
+
+	case FSR_RD_RM:		/* toward -Inf iff negative */
+		inf = sign;
+		break;
+	}
+	return (inf);
+}
+
+/*
+ * fpn -> int (int value returned as return value).
+ *
+ * N.B.: this conversion always rounds towards zero (this is a peculiarity
+ * of the SPARC instruction set).
+ */
+u_int
+fpu_ftoi(fe, fp)
+	struct fpemu *fe;
+	register struct fpn *fp;
+{
+	register u_int i;
+	register int sign, exp;
+
+	sign = fp->fp_sign;
+	switch (fp->fp_class) {
+
+	case FPC_ZERO:
+		return (0);
+
+	case FPC_NUM:
+		/*
+		 * If exp >= 2^32, overflow.  Otherwise shift value right
+		 * into last mantissa word (this will not exceed 0xffffffff),
+		 * shifting any guard and round bits out into the sticky
+		 * bit.  Then ``round'' towards zero, i.e., just set an
+		 * inexact exception if sticky is set (see round()).
+		 * If the result is > 0x80000000, or is positive and equals
+		 * 0x80000000, overflow; otherwise the last fraction word
+		 * is the result.
+		 */
+		if ((exp = fp->fp_exp) >= 32)
+			break;
+		/* NB: the following includes exp < 0 cases */
+		if (fpu_shr(fp, FP_NMANT - 1 - exp) != 0)
+			fe->fe_cx |= FSR_NX;
+		i = fp->fp_mant[3];
+		if (i >= ((u_int)0x80000000 + sign))
+			break;
+		return (sign ? -i : i);
+
+	default:		/* Inf, qNaN, sNaN */
+		break;
+	}
+	/* overflow: replace any inexact exception with invalid */
+	fe->fe_cx = (fe->fe_cx & ~FSR_NX) | FSR_NV;
+	return (0x7fffffff + sign);
+}
+
+#ifdef SUN4U
+/*
+ * fpn -> extended int (high bits of int value returned as return value).
+ *
+ * N.B.: this conversion always rounds towards zero (this is a peculiarity
+ * of the SPARC instruction set).
+ */
+u_int
+fpu_ftox(fe, fp, res)
+	struct fpemu *fe;
+	register struct fpn *fp;
+	u_int *res;
+{
+	register u_int64_t i;
+	register int sign, exp;
+
+	sign = fp->fp_sign;
+	switch (fp->fp_class) {
+
+	case FPC_ZERO:
+		res[1] = 0;
+		return (0);
+
+	case FPC_NUM:
+		/*
+		 * If exp >= 2^64, overflow.  Otherwise shift value right
+		 * into last mantissa word (this will not exceed 0xffffffffffffffff),
+		 * shifting any guard and round bits out into the sticky
+		 * bit.  Then ``round'' towards zero, i.e., just set an
+		 * inexact exception if sticky is set (see round()).
+		 * If the result is > 0x8000000000000000, or is positive and equals
+		 * 0x8000000000000000, overflow; otherwise the last fraction word
+		 * is the result.
+		 */
+		if ((exp = fp->fp_exp) >= 64)
+			break;
+		/* NB: the following includes exp < 0 cases */
+		if (fpu_shr(fp, FP_NMANT - 1 - exp) != 0)
+			fe->fe_cx |= FSR_NX;
+		i = ((u_int64_t)fp->fp_mant[2]<<32)|fp->fp_mant[3];
+		if (i >= ((u_int64_t)0x8000000000000000LL + sign))
+			break;
+		return (sign ? -i : i);
+
+	default:		/* Inf, qNaN, sNaN */
+		break;
+	}
+	/* overflow: replace any inexact exception with invalid */
+	fe->fe_cx = (fe->fe_cx & ~FSR_NX) | FSR_NV;
+	return (0x7fffffffffffffffLL + sign);
+}
+#endif /* SUN4U */
+
+/*
+ * fpn -> single (32 bit single returned as return value).
+ * We assume <= 29 bits in a single-precision fraction (1.f part).
+ */
+u_int
+fpu_ftos(fe, fp)
+	struct fpemu *fe;
+	register struct fpn *fp;
+{
+	register u_int sign = fp->fp_sign << 31;
+	register int exp;
+
+#define	SNG_EXP(e)	((e) << SNG_FRACBITS)	/* makes e an exponent */
+#define	SNG_MASK	(SNG_EXP(1) - 1)	/* mask for fraction */
+
+	/* Take care of non-numbers first. */
+	if (ISNAN(fp)) {
+		/*
+		 * Preserve upper bits of NaN, per SPARC V8 appendix N.
+		 * Note that fp->fp_mant[0] has the quiet bit set,
+		 * even if it is classified as a signalling NaN.
+		 */
+		(void) fpu_shr(fp, FP_NMANT - 1 - SNG_FRACBITS);
+		exp = SNG_EXP_INFNAN;
+		goto done;
+	}
+	if (ISINF(fp))
+		return (sign | SNG_EXP(SNG_EXP_INFNAN));
+	if (ISZERO(fp))
+		return (sign);
+
+	/*
+	 * Normals (including subnormals).  Drop all the fraction bits
+	 * (including the explicit ``implied'' 1 bit) down into the
+	 * single-precision range.  If the number is subnormal, move
+	 * the ``implied'' 1 into the explicit range as well, and shift
+	 * right to introduce leading zeroes.  Rounding then acts
+	 * differently for normals and subnormals: the largest subnormal
+	 * may round to the smallest normal (1.0 x 2^minexp), or may
+	 * remain subnormal.  In the latter case, signal an underflow
+	 * if the result was inexact or if underflow traps are enabled.
+	 *
+	 * Rounding a normal, on the other hand, always produces another
+	 * normal (although either way the result might be too big for
+	 * single precision, and cause an overflow).  If rounding a
+	 * normal produces 2.0 in the fraction, we need not adjust that
+	 * fraction at all, since both 1.0 and 2.0 are zero under the
+	 * fraction mask.
+	 *
+	 * Note that the guard and round bits vanish from the number after
+	 * rounding.
+	 */
+	if ((exp = fp->fp_exp + SNG_EXP_BIAS) <= 0) {	/* subnormal */
+		/* -NG for g,r; -SNG_FRACBITS-exp for fraction */
+		(void) fpu_shr(fp, FP_NMANT - FP_NG - SNG_FRACBITS - exp);
+		if (round(fe, fp) && fp->fp_mant[3] == SNG_EXP(1))
+			return (sign | SNG_EXP(1) | 0);
+		if ((fe->fe_cx & FSR_NX) ||
+		    (fe->fe_fsr & (FSR_UF << FSR_TEM_SHIFT)))
+			fe->fe_cx |= FSR_UF;
+		return (sign | SNG_EXP(0) | fp->fp_mant[3]);
+	}
+	/* -FP_NG for g,r; -1 for implied 1; -SNG_FRACBITS for fraction */
+	(void) fpu_shr(fp, FP_NMANT - FP_NG - 1 - SNG_FRACBITS);
+#ifdef DIAGNOSTIC
+	if ((fp->fp_mant[3] & SNG_EXP(1 << FP_NG)) == 0)
+		panic("fpu_ftos");
+#endif
+	if (round(fe, fp) && fp->fp_mant[3] == SNG_EXP(2))
+		exp++;
+	if (exp >= SNG_EXP_INFNAN) {
+		/* overflow to inf or to max single */
+		fe->fe_cx |= FSR_OF | FSR_NX;
+		if (toinf(fe, sign))
+			return (sign | SNG_EXP(SNG_EXP_INFNAN));
+		return (sign | SNG_EXP(SNG_EXP_INFNAN - 1) | SNG_MASK);
+	}
+done:
+	/* phew, made it */
+	return (sign | SNG_EXP(exp) | (fp->fp_mant[3] & SNG_MASK));
+}
+
+/*
+ * fpn -> double (32 bit high-order result returned; 32-bit low order result
+ * left in res[1]).  Assumes <= 61 bits in double precision fraction.
+ *
+ * This code mimics fpu_ftos; see it for comments.
+ */
+u_int
+fpu_ftod(fe, fp, res)
+	struct fpemu *fe;
+	register struct fpn *fp;
+	u_int *res;
+{
+	register u_int sign = fp->fp_sign << 31;
+	register int exp;
+
+#define	DBL_EXP(e)	((e) << (DBL_FRACBITS & 31))
+#define	DBL_MASK	(DBL_EXP(1) - 1)
+
+	if (ISNAN(fp)) {
+		(void) fpu_shr(fp, FP_NMANT - 1 - DBL_FRACBITS);
+		exp = DBL_EXP_INFNAN;
+		goto done;
+	}
+	if (ISINF(fp)) {
+		sign |= DBL_EXP(DBL_EXP_INFNAN);
+		goto zero;
+	}
+	if (ISZERO(fp)) {
+zero:		res[1] = 0;
+		return (sign);
+	}
+
+	if ((exp = fp->fp_exp + DBL_EXP_BIAS) <= 0) {
+		(void) fpu_shr(fp, FP_NMANT - FP_NG - DBL_FRACBITS - exp);
+		if (round(fe, fp) && fp->fp_mant[2] == DBL_EXP(1)) {
+			res[1] = 0;
+			return (sign | DBL_EXP(1) | 0);
+		}
+		if ((fe->fe_cx & FSR_NX) ||
+		    (fe->fe_fsr & (FSR_UF << FSR_TEM_SHIFT)))
+			fe->fe_cx |= FSR_UF;
+		exp = 0;
+		goto done;
+	}
+	(void) fpu_shr(fp, FP_NMANT - FP_NG - 1 - DBL_FRACBITS);
+	if (round(fe, fp) && fp->fp_mant[2] == DBL_EXP(2))
+		exp++;
+	if (exp >= DBL_EXP_INFNAN) {
+		fe->fe_cx |= FSR_OF | FSR_NX;
+		if (toinf(fe, sign)) {
+			res[1] = 0;
+			return (sign | DBL_EXP(DBL_EXP_INFNAN) | 0);
+		}
+		res[1] = ~0;
+		return (sign | DBL_EXP(DBL_EXP_INFNAN) | DBL_MASK);
+	}
+done:
+	res[1] = fp->fp_mant[3];
+	return (sign | DBL_EXP(exp) | (fp->fp_mant[2] & DBL_MASK));
+}
+
+/*
+ * fpn -> extended (32 bit high-order result returned; low-order fraction
+ * words left in res[1]..res[3]).  Like ftod, which is like ftos ... but
+ * our internal format *is* extended precision, plus 2 bits for guard/round,
+ * so we can avoid a small bit of work.
+ */
+u_int
+fpu_ftoq(fe, fp, res)
+	struct fpemu *fe;
+	register struct fpn *fp;
+	u_int *res;
+{
+	register u_int sign = fp->fp_sign << 31;
+	register int exp;
+
+#define	EXT_EXP(e)	((e) << (EXT_FRACBITS & 31))
+#define	EXT_MASK	(EXT_EXP(1) - 1)
+
+	if (ISNAN(fp)) {
+		(void) fpu_shr(fp, 2);	/* since we are not rounding */
+		exp = EXT_EXP_INFNAN;
+		goto done;
+	}
+	if (ISINF(fp)) {
+		sign |= EXT_EXP(EXT_EXP_INFNAN);
+		goto zero;
+	}
+	if (ISZERO(fp)) {
+zero:		res[1] = res[2] = res[3] = 0;
+		return (sign);
+	}
+
+	if ((exp = fp->fp_exp + EXT_EXP_BIAS) <= 0) {
+		(void) fpu_shr(fp, FP_NMANT - FP_NG - EXT_FRACBITS - exp);
+		if (round(fe, fp) && fp->fp_mant[0] == EXT_EXP(1)) {
+			res[1] = res[2] = res[3] = 0;
+			return (sign | EXT_EXP(1) | 0);
+		}
+		if ((fe->fe_cx & FSR_NX) ||
+		    (fe->fe_fsr & (FSR_UF << FSR_TEM_SHIFT)))
+			fe->fe_cx |= FSR_UF;
+		exp = 0;
+		goto done;
+	}
+	/* Since internal == extended, no need to shift here. */
+	if (round(fe, fp) && fp->fp_mant[0] == EXT_EXP(2))
+		exp++;
+	if (exp >= EXT_EXP_INFNAN) {
+		fe->fe_cx |= FSR_OF | FSR_NX;
+		if (toinf(fe, sign)) {
+			res[1] = res[2] = res[3] = 0;
+			return (sign | EXT_EXP(EXT_EXP_INFNAN) | 0);
+		}
+		res[1] = res[2] = res[3] = ~0;
+		return (sign | EXT_EXP(EXT_EXP_INFNAN) | EXT_MASK);
+	}
+done:
+	res[1] = fp->fp_mant[1];
+	res[2] = fp->fp_mant[2];
+	res[3] = fp->fp_mant[3];
+	return (sign | EXT_EXP(exp) | (fp->fp_mant[0] & EXT_MASK));
+}
+
+/*
+ * Implode an fpn, writing the result into the given space.
+ */
+void
+fpu_implode(fe, fp, type, space)
+	struct fpemu *fe;
+	register struct fpn *fp;
+	int type;
+	register u_int *space;
+{
+
+	switch (type) {
+
+#ifdef SUN4U
+	case FTYPE_LNG:
+		space[0] = fpu_ftox(fe, fp, space);
+		break;
+#endif /* SUN4U */
+
+	case FTYPE_INT:
+		space[0] = fpu_ftoi(fe, fp);
+		break;
+
+	case FTYPE_SNG:
+		space[0] = fpu_ftos(fe, fp);
+		break;
+
+	case FTYPE_DBL:
+		space[0] = fpu_ftod(fe, fp, space);
+		break;
+
+	case FTYPE_EXT:
+		/* funky rounding precision options ?? */
+		space[0] = fpu_ftoq(fe, fp, space);
+		break;
+
+	default:
+		panic("fpu_implode");
+	}
+}