Kernel FPU emulator, chain saw edition.

1 files changed, 168 insertions, 0 deletions

diff --git a/arch/mips/math-emu/sp_div.c b/arch/mips/math-emu/sp_div.c
new file mode 100644
index 000000000..187f14fd3
--- /dev/null
+++ b/arch/mips/math-emu/sp_div.c
@@ -0,0 +1,168 @@
+/* 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 <limits.h>
+#ifdef __KERNEL__
+#define assert(expr) ((void)0)
+#else
+#include <assert.h>
+#endif
+#include <stdarg.h>
+
+#include "ieee754sp.h"
+
+ieee754sp ieee754sp_div(ieee754sp x, ieee754sp y)
+{
+	COMPXSP;
+	COMPYSP;
+
+	CLEARCX;
+
+	EXPLODEXSP;
+	EXPLODEYSP;
+
+	switch (CLPAIR(xc, yc)) {
+	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
+		return ieee754sp_nanxcpt(ieee754sp_bestnan(x, y), "div", x,
+					 y);
+
+	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
+	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
+	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
+	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
+	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
+		return ieee754sp_nanxcpt(y, "div", x, y);
+
+	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
+	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
+	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
+	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
+	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
+		return ieee754sp_nanxcpt(x, "div", x, y);
+
+	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
+		return ieee754sp_bestnan(x, y);
+
+	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
+	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
+	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
+	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
+		return y;
+
+	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
+	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
+	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
+	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):
+		return x;
+
+
+		/* Infinity handeling 
+		 */
+
+	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
+		SETCX(IEEE754_INVALID_OPERATION);
+		return ieee754sp_xcpt(ieee754sp_indef(), "div", x, y);
+
+	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
+	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
+	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
+		return ieee754sp_zero(xs ^ ys);
+
+	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
+	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
+	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
+		return ieee754sp_inf(xs ^ ys);
+
+		/* Zero handeling 
+		 */
+
+	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
+		SETCX(IEEE754_INVALID_OPERATION);
+		return ieee754sp_xcpt(ieee754sp_indef(), "div", x, y);
+
+	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
+	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
+		SETCX(IEEE754_ZERO_DIVIDE);
+		return ieee754sp_xcpt(ieee754sp_inf(xs ^ ys), "div", x, y);
+
+	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
+	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
+		return ieee754sp_zero(xs == ys ? 0 : 1);
+
+	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
+		SPDNORMX;
+
+	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
+		SPDNORMY;
+		break;
+
+	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
+		SPDNORMX;
+		break;
+
+	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM):
+		break;
+	}
+	assert(xm & SP_HIDDEN_BIT);
+	assert(ym & SP_HIDDEN_BIT);
+
+	/* provide rounding space */
+	xm <<= 3;
+	ym <<= 3;
+
+	{
+		/* now the dirty work */
+
+		unsigned rm = 0;
+		int re = xe - ye;
+		unsigned bm;
+
+		for (bm = SP_MBIT(SP_MBITS + 2); bm; bm >>= 1) {
+			if (xm >= ym) {
+				xm -= ym;
+				rm |= bm;
+				if (xm == 0)
+					break;
+			}
+			xm <<= 1;
+		}
+		rm <<= 1;
+		if (xm)
+			rm |= 1;	/* have remainder, set sticky */
+
+		assert(rm);
+
+		/* normalise rm to rounding precision ?
+		 */
+		while ((rm >> (SP_MBITS + 3)) == 0) {
+			rm <<= 1;
+			re--;
+		}
+
+		SPNORMRET2(xs == ys ? 0 : 1, re, rm, "div", x, y);
+	}
+}