aboutsummaryrefslogtreecommitdiff
path: root/arch/mips/math-emu/dp_sub.c
diff options
context:
space:
mode:
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/dp_sub.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/dp_sub.c')
-rw-r--r--arch/mips/math-emu/dp_sub.c191
1 files changed, 191 insertions, 0 deletions
diff --git a/arch/mips/math-emu/dp_sub.c b/arch/mips/math-emu/dp_sub.c
new file mode 100644
index 00000000000..b30c5b1f1a2
--- /dev/null
+++ b/arch/mips/math-emu/dp_sub.c
@@ -0,0 +1,191 @@
+/* IEEE754 floating point arithmetic
+ * double precision: common utilities
+ */
+/*
+ * 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 "ieee754dp.h"
+
+ieee754dp ieee754dp_sub(ieee754dp x, ieee754dp y)
+{
+ COMPXDP;
+ COMPYDP;
+
+ EXPLODEXDP;
+ EXPLODEYDP;
+
+ CLEARCX;
+
+ FLUSHXDP;
+ FLUSHYDP;
+
+ switch (CLPAIR(xc, yc)) {
+ case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
+ case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
+ case CLPAIR(IEEE754_CLASS_SNAN, 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):
+ 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):
+ SETCX(IEEE754_INVALID_OPERATION);
+ return ieee754dp_nanxcpt(ieee754dp_indef(), "sub", 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_QNAN):
+ 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 handling
+ */
+
+ case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
+ if (xs != ys)
+ return x;
+ SETCX(IEEE754_INVALID_OPERATION);
+ return ieee754dp_xcpt(ieee754dp_indef(), "sub", x, y);
+
+ case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
+ case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
+ case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
+ return ieee754dp_inf(ys ^ 1);
+
+ 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 x;
+
+ /* Zero handling
+ */
+
+ case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
+ if (xs != ys)
+ return x;
+ else
+ return ieee754dp_zero(ieee754_csr.rm ==
+ IEEE754_RD);
+
+ case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
+ case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
+ return x;
+
+ case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
+ case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
+ /* quick fix up */
+ DPSIGN(y) ^= 1;
+ return y;
+
+ case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
+ DPDNORMX;
+ /* FAAL THOROUGH */
+
+ case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
+ /* normalize ym,ye */
+ DPDNORMY;
+ break;
+
+ case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
+ /* normalize xm,xe */
+ DPDNORMX;
+ break;
+
+ case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM):
+ break;
+ }
+ /* flip sign of y and handle as add */
+ ys ^= 1;
+
+ assert(xm & DP_HIDDEN_BIT);
+ assert(ym & DP_HIDDEN_BIT);
+
+
+ /* provide guard,round and stick bit dpace */
+ xm <<= 3;
+ ym <<= 3;
+
+ if (xe > ye) {
+ /* have to shift y fraction right to align
+ */
+ int s = xe - ye;
+ ym = XDPSRS(ym, s);
+ ye += s;
+ } else if (ye > xe) {
+ /* have to shift x fraction right to align
+ */
+ int s = ye - xe;
+ xm = XDPSRS(xm, s);
+ xe += s;
+ }
+ assert(xe == ye);
+ assert(xe <= DP_EMAX);
+
+ if (xs == ys) {
+ /* generate 28 bit result of adding two 27 bit numbers
+ */
+ xm = xm + ym;
+ xe = xe;
+ xs = xs;
+
+ if (xm >> (DP_MBITS + 1 + 3)) { /* carry out */
+ xm = XDPSRS1(xm); /* shift preserving sticky */
+ xe++;
+ }
+ } else {
+ if (xm >= ym) {
+ xm = xm - ym;
+ xe = xe;
+ xs = xs;
+ } else {
+ xm = ym - xm;
+ xe = xe;
+ xs = ys;
+ }
+ if (xm == 0) {
+ if (ieee754_csr.rm == IEEE754_RD)
+ return ieee754dp_zero(1); /* round negative inf. => sign = -1 */
+ else
+ return ieee754dp_zero(0); /* other round modes => sign = 1 */
+ }
+
+ /* normalize to rounding precision
+ */
+ while ((xm >> (DP_MBITS + 3)) == 0) {
+ xm <<= 1;
+ xe--;
+ }
+ }
+ DPNORMRET2(xs, xe, xm, "sub", x, y);
+}