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-rw-r--r--arch/mips/math-emu/dp_tlong.c100
1 files changed, 100 insertions, 0 deletions
diff --git a/arch/mips/math-emu/dp_tlong.c b/arch/mips/math-emu/dp_tlong.c
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+++ b/arch/mips/math-emu/dp_tlong.c
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+// 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"
+
+s64 ieee754dp_tlong(union ieee754dp x)
+{
+ u64 residue;
+ int round;
+ int sticky;
+ int odd;
+
+ COMPXDP;
+
+ ieee754_clearcx();
+
+ EXPLODEXDP;
+ FLUSHXDP;
+
+ switch (xc) {
+ case IEEE754_CLASS_SNAN:
+ case IEEE754_CLASS_QNAN:
+ ieee754_setcx(IEEE754_INVALID_OPERATION);
+ return ieee754di_indef();
+
+ case IEEE754_CLASS_INF:
+ ieee754_setcx(IEEE754_INVALID_OPERATION);
+ return ieee754di_overflow(xs);
+
+ case IEEE754_CLASS_ZERO:
+ return 0;
+
+ case IEEE754_CLASS_DNORM:
+ case IEEE754_CLASS_NORM:
+ break;
+ }
+ if (xe >= 63) {
+ /* look for valid corner case */
+ if (xe == 63 && xs && xm == DP_HIDDEN_BIT)
+ return -0x8000000000000000LL;
+ /* Set invalid. We will only use overflow for floating
+ point overflow */
+ ieee754_setcx(IEEE754_INVALID_OPERATION);
+ return ieee754di_overflow(xs);
+ }
+ /* oh gawd */
+ if (xe > DP_FBITS) {
+ xm <<= xe - DP_FBITS;
+ } else if (xe < DP_FBITS) {
+ if (xe < -1) {
+ residue = xm;
+ round = 0;
+ sticky = residue != 0;
+ xm = 0;
+ } else {
+ /* Shifting a u64 64 times does not work,
+ * so we do it in two steps. Be aware that xe
+ * may be -1 */
+ residue = xm << (xe + 1);
+ residue <<= 63 - DP_FBITS;
+ round = (residue >> 63) != 0;
+ sticky = (residue << 1) != 0;
+ xm >>= DP_FBITS - xe;
+ }
+ odd = (xm & 0x1) != 0x0;
+ switch (ieee754_csr.rm) {
+ case FPU_CSR_RN:
+ if (round && (sticky || odd))
+ xm++;
+ break;
+ case FPU_CSR_RZ:
+ break;
+ case FPU_CSR_RU: /* toward +Infinity */
+ if ((round || sticky) && !xs)
+ xm++;
+ break;
+ case FPU_CSR_RD: /* toward -Infinity */
+ if ((round || sticky) && xs)
+ xm++;
+ break;
+ }
+ if ((xm >> 63) != 0) {
+ /* This can happen after rounding */
+ ieee754_setcx(IEEE754_INVALID_OPERATION);
+ return ieee754di_overflow(xs);
+ }
+ if (round || sticky)
+ ieee754_setcx(IEEE754_INEXACT);
+ }
+ if (xs)
+ return -xm;
+ else
+ return xm;
+}