Restore a more maintainable version of the 64bit multiply code.
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@3439 c046a42c-6fe2-441c-8c8c-71466251a162
diff --git a/host-utils.c b/host-utils.c
index cf2c6f8..d0d780e 100644
--- a/host-utils.c
+++ b/host-utils.c
@@ -1,6 +1,7 @@
/*
* Utility compute operations used by translated code.
*
+ * Copyright (c) 2003 Fabrice Bellard
* Copyright (c) 2007 Aurelien Jarno
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
@@ -24,54 +25,88 @@
#include "vl.h"
-/* Signed 64x64 -> 128 multiplication */
-
-void muls64(int64_t *phigh, int64_t *plow, int64_t a, int64_t b)
+/* Long integer helpers */
+static void add128 (uint64_t *plow, uint64_t *phigh, uint64_t a, uint64_t b)
{
-#if defined(__x86_64__)
- __asm__ ("imul %0\n\t"
- : "=d" (*phigh), "=a" (*plow)
- : "a" (a), "0" (b)
- );
-#else
- int64_t ph;
- uint64_t pm1, pm2, pl;
-
- pl = (uint64_t)((uint32_t)a) * (uint64_t)((uint32_t)b);
- pm1 = (a >> 32) * (uint32_t)b;
- pm2 = (uint32_t)a * (b >> 32);
- ph = (a >> 32) * (b >> 32);
-
- ph += (int64_t)pm1 >> 32;
- ph += (int64_t)pm2 >> 32;
- pm1 = (uint64_t)((uint32_t)pm1) + (uint64_t)((uint32_t)pm2) + (pl >> 32);
-
- *phigh = ph + ((int64_t)pm1 >> 32);
- *plow = (pm1 << 32) + (uint32_t)pl;
-#endif
+ *plow += a;
+ /* carry test */
+ if (*plow < a)
+ (*phigh)++;
+ *phigh += b;
}
+static void neg128 (uint64_t *plow, uint64_t *phigh)
+{
+ *plow = ~*plow;
+ *phigh = ~*phigh;
+ add128(plow, phigh, 1, 0);
+}
+
+static void mul64 (uint64_t *plow, uint64_t *phigh, uint64_t a, uint64_t b)
+{
+ uint32_t a0, a1, b0, b1;
+ uint64_t v;
+
+ a0 = a;
+ a1 = a >> 32;
+
+ b0 = b;
+ b1 = b >> 32;
+
+ v = (uint64_t)a0 * (uint64_t)b0;
+ *plow = v;
+ *phigh = 0;
+
+ v = (uint64_t)a0 * (uint64_t)b1;
+ add128(plow, phigh, v << 32, v >> 32);
+
+ v = (uint64_t)a1 * (uint64_t)b0;
+ add128(plow, phigh, v << 32, v >> 32);
+
+ v = (uint64_t)a1 * (uint64_t)b1;
+ *phigh += v;
+}
+
+
/* Unsigned 64x64 -> 128 multiplication */
-void mulu64(uint64_t *phigh, uint64_t *plow, uint64_t a, uint64_t b)
+void mulu64 (uint64_t *plow, uint64_t *phigh, uint64_t a, uint64_t b)
{
#if defined(__x86_64__)
__asm__ ("mul %0\n\t"
: "=d" (*phigh), "=a" (*plow)
- : "a" (a), "0" (b)
- );
+ : "a" (a), "0" (b));
#else
- uint64_t ph, pm1, pm2, pl;
+ mul64(plow, phigh, a, b);
+#endif
+#if defined(DEBUG_MULDIV)
+ printf("mulu64: 0x%016llx * 0x%016llx = 0x%016llx%016llx\n",
+ a, b, *phigh, *plow);
+#endif
+}
- pl = (uint64_t)((uint32_t)a) * (uint64_t)((uint32_t)b);
- pm1 = (a >> 32) * (uint32_t)b;
- pm2 = (uint32_t)a * (b >> 32);
- ph = (a >> 32) * (b >> 32);
+/* Signed 64x64 -> 128 multiplication */
+void muls64 (uint64_t *plow, uint64_t *phigh, int64_t a, int64_t b)
+{
+#if defined(__x86_64__)
+ __asm__ ("imul %0\n\t"
+ : "=d" (*phigh), "=a" (*plow)
+ : "a" (a), "0" (b));
+#else
+ int sa, sb;
- ph += pm1 >> 32;
- ph += pm2 >> 32;
- pm1 = (uint64_t)((uint32_t)pm1) + (uint64_t)((uint32_t)pm2) + (pl >> 32);
-
- *phigh = ph + (pm1 >> 32);
- *plow = (pm1 << 32) + (uint32_t)pl;
+ sa = (a < 0);
+ if (sa)
+ a = -a;
+ sb = (b < 0);
+ if (sb)
+ b = -b;
+ mul64(plow, phigh, a, b);
+ if (sa ^ sb) {
+ neg128(plow, phigh);
+ }
+#endif
+#if defined(DEBUG_MULDIV)
+ printf("muls64: 0x%016llx * 0x%016llx = 0x%016llx%016llx\n",
+ a, b, *phigh, *plow);
#endif
}
