diff options
| -rw-r--r-- | util/host-utils.c | 92 |
1 files changed, 38 insertions, 54 deletions
diff --git a/util/host-utils.c b/util/host-utils.c index 2d06a2cb78..f0784d6335 100644 --- a/util/host-utils.c +++ b/util/host-utils.c @@ -27,79 +27,63 @@ #include <stdint.h> #include "qemu/host-utils.h" -//#define DEBUG_MULDIV - /* Long integer helpers */ #ifndef CONFIG_INT128 -static void add128 (uint64_t *plow, uint64_t *phigh, uint64_t a, uint64_t b) -{ - *plow += a; - /* carry test */ - if (*plow < a) - (*phigh)++; - *phigh += b; -} - -static void neg128 (uint64_t *plow, uint64_t *phigh) +static inline void mul64(uint64_t *plow, uint64_t *phigh, + uint64_t a, uint64_t b) { - *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; + typedef union { + uint64_t ll; + struct { +#ifdef HOST_WORDS_BIGENDIAN + uint32_t high, low; +#else + uint32_t low, high; +#endif + } l; + } LL; + LL rl, rm, rn, rh, a0, b0; + uint64_t c; - v = (uint64_t)a0 * (uint64_t)b0; - *plow = v; - *phigh = 0; + a0.ll = a; + b0.ll = b; - v = (uint64_t)a0 * (uint64_t)b1; - add128(plow, phigh, v << 32, v >> 32); + rl.ll = (uint64_t)a0.l.low * b0.l.low; + rm.ll = (uint64_t)a0.l.low * b0.l.high; + rn.ll = (uint64_t)a0.l.high * b0.l.low; + rh.ll = (uint64_t)a0.l.high * b0.l.high; - v = (uint64_t)a1 * (uint64_t)b0; - add128(plow, phigh, v << 32, v >> 32); + c = (uint64_t)rl.l.high + rm.l.low + rn.l.low; + rl.l.high = c; + c >>= 32; + c = c + rm.l.high + rn.l.high + rh.l.low; + rh.l.low = c; + rh.l.high += (uint32_t)(c >> 32); - v = (uint64_t)a1 * (uint64_t)b1; - *phigh += v; + *plow = rl.ll; + *phigh = rh.ll; } /* Unsigned 64x64 -> 128 multiplication */ void mulu64 (uint64_t *plow, uint64_t *phigh, uint64_t a, uint64_t b) { mul64(plow, phigh, a, b); -#if defined(DEBUG_MULDIV) - printf("mulu64: 0x%016llx * 0x%016llx = 0x%016llx%016llx\n", - a, b, *phigh, *plow); -#endif } /* Signed 64x64 -> 128 multiplication */ void muls64 (uint64_t *plow, uint64_t *phigh, int64_t a, int64_t b) { - int sa, sb; + uint64_t rh; - 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); + mul64(plow, &rh, a, b); + + /* Adjust for signs. */ + if (b < 0) { + rh -= a; } -#if defined(DEBUG_MULDIV) - printf("muls64: 0x%016llx * 0x%016llx = 0x%016llx%016llx\n", - a, b, *phigh, *plow); -#endif + if (a < 0) { + rh -= b; + } + *phigh = rh; } #endif /* !CONFIG_INT128 */ |