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-rw-r--r--arch/mips/math-emu/dp_sub.c172
1 files changed, 172 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 000000000..08474ad2a
--- /dev/null
+++ b/arch/mips/math-emu/dp_sub.c
@@ -0,0 +1,172 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* IEEE754 floating point arithmetic
+ * double precision: common utilities
+ */
+/*
+ * MIPS floating point support
+ * Copyright (C) 1994-2000 Algorithmics Ltd.
+ */
+
+#include "ieee754dp.h"
+
+union ieee754dp ieee754dp_sub(union ieee754dp x, union ieee754dp y)
+{
+ int s;
+
+ COMPXDP;
+ COMPYDP;
+
+ EXPLODEXDP;
+ EXPLODEYDP;
+
+ ieee754_clearcx();
+
+ FLUSHXDP;
+ FLUSHYDP;
+
+ switch (CLPAIR(xc, yc)) {
+ 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 ieee754dp_nanxcpt(y);
+
+ case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
+ 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 ieee754dp_nanxcpt(x);
+
+ 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;
+ ieee754_setcx(IEEE754_INVALID_OPERATION);
+ return ieee754dp_indef();
+
+ 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 == FPU_CSR_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;
+ fallthrough;
+ 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
+ */
+ s = xe - ye;
+ ym = XDPSRS(ym, s);
+ ye += s;
+ } else if (ye > xe) {
+ /*
+ * Have to shift x fraction right to align
+ */
+ 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;
+
+ if (xm >> (DP_FBITS + 1 + 3)) { /* carry out */
+ xm = XDPSRS1(xm); /* shift preserving sticky */
+ xe++;
+ }
+ } else {
+ if (xm >= ym) {
+ xm = xm - ym;
+ } else {
+ xm = ym - xm;
+ xs = ys;
+ }
+ if (xm == 0) {
+ if (ieee754_csr.rm == FPU_CSR_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_FBITS + 3)) == 0) {
+ xm <<= 1;
+ xe--;
+ }
+ }
+
+ return ieee754dp_format(xs, xe, xm);
+}