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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/mips/math-emu/ieee754sp.c
Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'arch/mips/math-emu/ieee754sp.c')
-rw-r--r--arch/mips/math-emu/ieee754sp.c243
1 files changed, 243 insertions, 0 deletions
diff --git a/arch/mips/math-emu/ieee754sp.c b/arch/mips/math-emu/ieee754sp.c
new file mode 100644
index 000000000000..adda851cd04f
--- /dev/null
+++ b/arch/mips/math-emu/ieee754sp.c
@@ -0,0 +1,243 @@
+/* IEEE754 floating point arithmetic
+ * single precision
+ */
+/*
+ * MIPS floating point support
+ * Copyright (C) 1994-2000 Algorithmics Ltd.
+ * 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));
+ 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 (!SETANDTESTCX(IEEE754_INVALID_OPERATION)) {
+ /* not enabled convert to a quiet NaN */
+ SPMANT(r) &= (~SP_MBIT(SP_MBITS-1));
+ if (ieee754sp_isnan(r))
+ return r;
+ else
+ return ieee754sp_indef();
+ }
+
+ 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;
+}
+
+
+static unsigned get_rounding(int sn, unsigned xm)
+{
+ /* inexact must round of 3 bits
+ */
+ if (xm & (SP_MBIT(3) - 1)) {
+ 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;
+ }
+ }
+ return xm;
+}
+
+
+/* generate a normal/denormal number with over,under handling
+ * 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 don't 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);
+ SETCX(IEEE754_INEXACT);
+
+ switch(ieee754_csr.rm) {
+ case IEEE754_RN:
+ return ieee754sp_zero(sn);
+ case IEEE754_RZ:
+ return ieee754sp_zero(sn);
+ case IEEE754_RU: /* toward +Infinity */
+ if(sn == 0)
+ return ieee754sp_min(0);
+ else
+ return ieee754sp_zero(1);
+ case IEEE754_RD: /* toward -Infinity */
+ if(sn == 0)
+ return ieee754sp_zero(0);
+ else
+ return ieee754sp_min(1);
+ }
+ }
+
+ if (xe == SP_EMIN - 1
+ && get_rounding(sn, xm) >> (SP_MBITS + 1 + 3))
+ {
+ /* Not tiny after rounding */
+ SETCX(IEEE754_INEXACT);
+ xm = get_rounding(sn, xm);
+ xm >>= 1;
+ /* Clear grs bits */
+ xm &= ~(SP_MBIT(3) - 1);
+ xe++;
+ }
+ else {
+ /* 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);
+ if ((xm & (SP_HIDDEN_BIT << 3)) == 0) {
+ SETCX(IEEE754_UNDERFLOW);
+ }
+
+ /* inexact must round of 3 bits
+ */
+ xm = get_rounding(sn, xm);
+ /* 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);
+ SETCX(IEEE754_INEXACT);
+ /* -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);
+ if (ieee754_csr.mx & IEEE754_UNDERFLOW)
+ 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);
+ }
+}