patch-2.4.4 linux/arch/mips/math-emu/ieee754sp.c

• Lines: 198
• Date: Fri Apr 13 20:26:07 2001
• Orig file: v2.4.3/linux/arch/mips/math-emu/ieee754sp.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.4.3/linux/arch/mips/math-emu/ieee754sp.c linux/arch/mips/math-emu/ieee754sp.c
@@ -0,0 +1,197 @@
+/* IEEE754 floating point arithmetic
+ * single precision
+ */
+/*
+ * MIPS floating point support
+ * Copyright (C) 1994-2000 Algorithmics Ltd.  All rights reserved.
+ * http://www.algor.co.uk
+ *
+ * ########################################################################
+ *
+ *  This program is free software; you can distribute it and/or modify it
+ *  under the terms of the GNU General Public License (Version 2) as
+ *  published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope it will be useful, but WITHOUT
+ *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ *  for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
+ *
+ * ########################################################################
+ */
+
+
+#include "ieee754sp.h"
+
+int ieee754sp_class(ieee754sp x)
+{
+	COMPXSP;
+	EXPLODEXSP;
+	return xc;
+}
+
+int ieee754sp_isnan(ieee754sp x)
+{
+	return ieee754sp_class(x) >= IEEE754_CLASS_SNAN;
+}
+
+int ieee754sp_issnan(ieee754sp x)
+{
+	assert(ieee754sp_isnan(x));
+	if (ieee754_csr.noq)
+		return 1;
+	return !(SPMANT(x) & SP_MBIT(SP_MBITS - 1));
+}
+
+
+ieee754sp ieee754sp_xcpt(ieee754sp r, const char *op, ...)
+{
+	struct ieee754xctx ax;
+
+	if (!TSTX())
+		return r;
+
+	ax.op = op;
+	ax.rt = IEEE754_RT_SP;
+	ax.rv.sp = r;
+	va_start(ax.ap, op);
+	ieee754_xcpt(&ax);
+	return ax.rv.sp;
+}
+
+ieee754sp ieee754sp_nanxcpt(ieee754sp r, const char *op, ...)
+{
+	struct ieee754xctx ax;
+
+	assert(ieee754sp_isnan(r));
+
+	if (!ieee754sp_issnan(r))	/* QNAN does not cause invalid op !! */
+		return r;
+
+	if (!SETCX(IEEE754_INVALID_OPERATION)) {
+		/* not enabled convert to a quiet NaN */
+		if (ieee754_csr.noq)
+			return r;
+		SPMANT(r) |= SP_MBIT(SP_MBITS - 1);
+		return r;
+	}
+
+	ax.op = op;
+	ax.rt = 0;
+	ax.rv.sp = r;
+	va_start(ax.ap, op);
+	ieee754_xcpt(&ax);
+	return ax.rv.sp;
+}
+
+ieee754sp ieee754sp_bestnan(ieee754sp x, ieee754sp y)
+{
+	assert(ieee754sp_isnan(x));
+	assert(ieee754sp_isnan(y));
+
+	if (SPMANT(x) > SPMANT(y))
+		return x;
+	else
+		return y;
+}
+
+
+/* generate a normal/denormal number with over,under handeling
+ * sn is sign
+ * xe is an unbiased exponent
+ * xm is 3bit extended precision value.
+ */
+ieee754sp ieee754sp_format(int sn, int xe, unsigned xm)
+{
+	assert(xm);		/* we dont gen exact zeros (probably should) */
+
+	assert((xm >> (SP_MBITS + 1 + 3)) == 0);	/* no execess */
+	assert(xm & (SP_HIDDEN_BIT << 3));
+
+	if (xe < SP_EMIN) {
+		/* strip lower bits */
+		int es = SP_EMIN - xe;
+
+		if (ieee754_csr.nod) {
+			SETCX(IEEE754_UNDERFLOW);
+			return ieee754sp_zero(sn);
+		}
+
+		/* sticky right shift es bits 
+		 */
+		SPXSRSXn(es);
+
+		assert((xm & (SP_HIDDEN_BIT << 3)) == 0);
+		assert(xe == SP_EMIN);
+	}
+	if (xm & (SP_MBIT(3) - 1)) {
+		SETCX(IEEE754_INEXACT);
+		/* inexact must round of 3 bits 
+		 */
+		switch (ieee754_csr.rm) {
+		case IEEE754_RZ:
+			break;
+		case IEEE754_RN:
+			xm += 0x3 + ((xm >> 3) & 1);
+			/* xm += (xm&0x8)?0x4:0x3 */
+			break;
+		case IEEE754_RU:	/* toward +Infinity */
+			if (!sn)	/* ?? */
+				xm += 0x8;
+			break;
+		case IEEE754_RD:	/* toward -Infinity */
+			if (sn)	/* ?? */
+				xm += 0x8;
+			break;
+		}
+		/* adjust exponent for rounding add overflowing 
+		 */
+		if (xm >> (SP_MBITS + 1 + 3)) {	/* add causes mantissa overflow */
+			xm >>= 1;
+			xe++;
+		}
+	}
+	/* strip grs bits */
+	xm >>= 3;
+
+	assert((xm >> (SP_MBITS + 1)) == 0);	/* no execess */
+	assert(xe >= SP_EMIN);
+
+	if (xe > SP_EMAX) {
+		SETCX(IEEE754_OVERFLOW);
+		/* -O can be table indexed by (rm,sn) */
+		switch (ieee754_csr.rm) {
+		case IEEE754_RN:
+			return ieee754sp_inf(sn);
+		case IEEE754_RZ:
+			return ieee754sp_max(sn);
+		case IEEE754_RU:	/* toward +Infinity */
+			if (sn == 0)
+				return ieee754sp_inf(0);
+			else
+				return ieee754sp_max(1);
+		case IEEE754_RD:	/* toward -Infinity */
+			if (sn == 0)
+				return ieee754sp_max(0);
+			else
+				return ieee754sp_inf(1);
+		}
+	}
+	/* gen norm/denorm/zero */
+
+	if ((xm & SP_HIDDEN_BIT) == 0) {
+		/* we underflow (tiny/zero) */
+		assert(xe == SP_EMIN);
+		SETCX(IEEE754_UNDERFLOW);
+		return buildsp(sn, SP_EMIN - 1 + SP_EBIAS, xm);
+	} else {
+		assert((xm >> (SP_MBITS + 1)) == 0);	/* no execess */
+		assert(xm & SP_HIDDEN_BIT);
+
+		return buildsp(sn, xe + SP_EBIAS, xm & ~SP_HIDDEN_BIT);
+	}
+}