qemu/host-utils.c

/*
 * 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
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include "vl.h"

//#define DEBUG_MULDIV

/* Long integer helpers */
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)
{
    *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 *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));
#else
    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
}

/* 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;

    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
}