Add a floating-point emulator so that a single userland or single ABI

can run on processors that don't have a FPU. This is typically the
case for Book E processors. While a tuned system will probably want
to use soft-float (or use a processor that has a FPU if the usage is
FP intensive enough), allowing hard-float on FPU-less systems gives
great portability and flexibility.

Obtained from: NetBSD

1 files changed, 262 insertions, 0 deletions

diff --git a/sys/powerpc/fpu/fpu_explode.c b/sys/powerpc/fpu/fpu_explode.c
new file mode 100644
index 0000000..70eef6a
--- /dev/null
+++ b/sys/powerpc/fpu/fpu_explode.c
@@ -0,0 +1,262 @@
+/*	$NetBSD: fpu_explode.c,v 1.6 2005/12/11 12:18:42 christos 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. 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_explode.c	8.1 (Berkeley) 6/11/93
+ */
+
+/*
+ * FPU subroutines: `explode' the machine's `packed binary' format numbers
+ * into our internal format.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/systm.h>
+#include <sys/types.h>
+
+#include <machine/fpu.h>
+#include <machine/ieee.h>
+#include <machine/reg.h>
+
+#include <powerpc/fpu/fpu_arith.h>
+#include <powerpc/fpu/fpu_emu.h>
+#include <powerpc/fpu/fpu_extern.h>
+#include <powerpc/fpu/fpu_instr.h>
+
+/*
+ * N.B.: in all of the following, we assume the FP format is
+ *
+ *	---------------------------
+ *	| s | exponent | fraction |
+ *	---------------------------
+ *
+ * (which represents -1**s * 1.fraction * 2**exponent), so that the
+ * sign bit is way at the top (bit 31), the exponent is next, and
+ * then the remaining bits mark the fraction.  A zero exponent means
+ * zero or denormalized (0.fraction rather than 1.fraction), and the
+ * maximum possible exponent, 2bias+1, signals inf (fraction==0) or NaN.
+ *
+ * Since the sign bit is always the topmost bit---this holds even for
+ * integers---we set that outside all the *tof functions.  Each function
+ * returns the class code for the new number (but note that we use
+ * FPC_QNAN for all NaNs; fpu_explode will fix this if appropriate).
+ */
+
+/*
+ * int -> fpn.
+ */
+int
+fpu_itof(struct fpn *fp, u_int i)
+{
+
+	if (i == 0)
+		return (FPC_ZERO);
+	/*
+	 * The value FP_1 represents 2^FP_LG, so set the exponent
+	 * there and let normalization fix it up.  Convert negative
+	 * numbers to sign-and-magnitude.  Note that this relies on
+	 * fpu_norm()'s handling of `supernormals'; see fpu_subr.c.
+	 */
+	fp->fp_exp = FP_LG;
+	fp->fp_mant[0] = (int)i < 0 ? -i : i;
+	fp->fp_mant[1] = 0;
+	fp->fp_mant[2] = 0;
+	fp->fp_mant[3] = 0;
+	fpu_norm(fp);
+	return (FPC_NUM);
+}
+
+/*
+ * 64-bit int -> fpn.
+ */
+int
+fpu_xtof(struct fpn *fp, u_int64_t i)
+{
+
+	if (i == 0)
+		return (FPC_ZERO);
+	/*
+	 * The value FP_1 represents 2^FP_LG, so set the exponent
+	 * there and let normalization fix it up.  Convert negative
+	 * numbers to sign-and-magnitude.  Note that this relies on
+	 * fpu_norm()'s handling of `supernormals'; see fpu_subr.c.
+	 */
+	fp->fp_exp = FP_LG2;
+	*((int64_t*)fp->fp_mant) = (int64_t)i < 0 ? -i : i;
+	fp->fp_mant[2] = 0;
+	fp->fp_mant[3] = 0;
+	fpu_norm(fp);
+	return (FPC_NUM);
+}
+
+#define	mask(nbits) ((1L << (nbits)) - 1)
+
+/*
+ * All external floating formats convert to internal in the same manner,
+ * as defined here.  Note that only normals get an implied 1.0 inserted.
+ */
+#define	FP_TOF(exp, expbias, allfrac, f0, f1, f2, f3) \
+	if (exp == 0) { \
+		if (allfrac == 0) \
+			return (FPC_ZERO); \
+		fp->fp_exp = 1 - expbias; \
+		fp->fp_mant[0] = f0; \
+		fp->fp_mant[1] = f1; \
+		fp->fp_mant[2] = f2; \
+		fp->fp_mant[3] = f3; \
+		fpu_norm(fp); \
+		return (FPC_NUM); \
+	} \
+	if (exp == (2 * expbias + 1)) { \
+		if (allfrac == 0) \
+			return (FPC_INF); \
+		fp->fp_mant[0] = f0; \
+		fp->fp_mant[1] = f1; \
+		fp->fp_mant[2] = f2; \
+		fp->fp_mant[3] = f3; \
+		return (FPC_QNAN); \
+	} \
+	fp->fp_exp = exp - expbias; \
+	fp->fp_mant[0] = FP_1 | f0; \
+	fp->fp_mant[1] = f1; \
+	fp->fp_mant[2] = f2; \
+	fp->fp_mant[3] = f3; \
+	return (FPC_NUM)
+
+/*
+ * 32-bit single precision -> fpn.
+ * We assume a single occupies at most (64-FP_LG) bits in the internal
+ * format: i.e., needs at most fp_mant[0] and fp_mant[1].
+ */
+int
+fpu_stof(struct fpn *fp, u_int i)
+{
+	int exp;
+	u_int frac, f0, f1;
+#define SNG_SHIFT (SNG_FRACBITS - FP_LG)
+
+	exp = (i >> (32 - 1 - SNG_EXPBITS)) & mask(SNG_EXPBITS);
+	frac = i & mask(SNG_FRACBITS);
+	f0 = frac >> SNG_SHIFT;
+	f1 = frac << (32 - SNG_SHIFT);
+	FP_TOF(exp, SNG_EXP_BIAS, frac, f0, f1, 0, 0);
+}
+
+/*
+ * 64-bit double -> fpn.
+ * We assume this uses at most (96-FP_LG) bits.
+ */
+int
+fpu_dtof(struct fpn *fp, u_int i, u_int j)
+{
+	int exp;
+	u_int frac, f0, f1, f2;
+#define DBL_SHIFT (DBL_FRACBITS - 32 - FP_LG)
+
+	exp = (i >> (32 - 1 - DBL_EXPBITS)) & mask(DBL_EXPBITS);
+	frac = i & mask(DBL_FRACBITS - 32);
+	f0 = frac >> DBL_SHIFT;
+	f1 = (frac << (32 - DBL_SHIFT)) | (j >> DBL_SHIFT);
+	f2 = j << (32 - DBL_SHIFT);
+	frac |= j;
+	FP_TOF(exp, DBL_EXP_BIAS, frac, f0, f1, f2, 0);
+}
+
+/*
+ * Explode the contents of a register / regpair / regquad.
+ * If the input is a signalling NaN, an NV (invalid) exception
+ * will be set.  (Note that nothing but NV can occur until ALU
+ * operations are performed.)
+ */
+void
+fpu_explode(struct fpemu *fe, struct fpn *fp, int type, int reg)
+{
+	u_int s, *space;
+	u_int64_t l, *xspace;
+
+	xspace = (u_int64_t *)&fe->fe_fpstate->fpreg[reg];
+	l = xspace[0];
+	space = (u_int *)&fe->fe_fpstate->fpreg[reg];
+	s = space[0];
+	fp->fp_sign = s >> 31;
+	fp->fp_sticky = 0;
+	switch (type) {
+
+	case FTYPE_LNG:
+		s = fpu_xtof(fp, l);
+		break;
+
+	case FTYPE_INT:
+		s = fpu_itof(fp, space[1]);
+		break;
+
+	case FTYPE_SNG:
+		s = fpu_stof(fp, s);
+		break;
+
+	case FTYPE_DBL:
+		s = fpu_dtof(fp, s, space[1]);
+		break;
+
+		panic("fpu_explode");
+		panic("fpu_explode: invalid type %d", type);
+	}
+
+	if (s == FPC_QNAN && (fp->fp_mant[0] & FP_QUIETBIT) == 0) {
+		/*
+		 * Input is a signalling NaN.  All operations that return
+		 * an input NaN operand put it through a ``NaN conversion'',
+		 * which basically just means ``turn on the quiet bit''.
+		 * We do this here so that all NaNs internally look quiet
+		 * (we can tell signalling ones by their class).
+		 */
+		fp->fp_mant[0] |= FP_QUIETBIT;
+		fe->fe_cx = FPSCR_VXSNAN;	/* assert invalid operand */
+		s = FPC_SNAN;
+	}
+	fp->fp_class = s;
+	DPRINTF(FPE_REG, ("fpu_explode: %%%c%d => ", (type == FTYPE_LNG) ? 'x' :
+		((type == FTYPE_INT) ? 'i' : 
+			((type == FTYPE_SNG) ? 's' :
+				((type == FTYPE_DBL) ? 'd' : '?'))),
+		reg));
+	DUMPFPN(FPE_REG, fp);
+	DPRINTF(FPE_REG, ("\n"));
+}