LXR qemu/util/host-utils.c

   1/*
   2 * Utility compute operations used by translated code.
   3 *
   4 * Copyright (c) 2003 Fabrice Bellard
   5 * Copyright (c) 2007 Aurelien Jarno
   6 *
   7 * Permission is hereby granted, free of charge, to any person obtaining a copy
   8 * of this software and associated documentation files (the "Software"), to deal
   9 * in the Software without restriction, including without limitation the rights
  10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  11 * copies of the Software, and to permit persons to whom the Software is
  12 * furnished to do so, subject to the following conditions:
  13 *
  14 * The above copyright notice and this permission notice shall be included in
  15 * all copies or substantial portions of the Software.
  16 *
  17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  20 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  23 * THE SOFTWARE.
  24 */
  25
  26#include "qemu/osdep.h"
  27#include "qemu/host-utils.h"
  28
  29/* Long integer helpers */
  30static inline void mul64(uint64_t *plow, uint64_t *phigh,
  31                         uint64_t a, uint64_t b)
  32{
  33    typedef union {
  34        uint64_t ll;
  35        struct {
  36#ifdef HOST_WORDS_BIGENDIAN
  37            uint32_t high, low;
  38#else
  39            uint32_t low, high;
  40#endif
  41        } l;
  42    } LL;
  43    LL rl, rm, rn, rh, a0, b0;
  44    uint64_t c;
  45
  46    a0.ll = a;
  47    b0.ll = b;
  48
  49    rl.ll = (uint64_t)a0.l.low * b0.l.low;
  50    rm.ll = (uint64_t)a0.l.low * b0.l.high;
  51    rn.ll = (uint64_t)a0.l.high * b0.l.low;
  52    rh.ll = (uint64_t)a0.l.high * b0.l.high;
  53
  54    c = (uint64_t)rl.l.high + rm.l.low + rn.l.low;
  55    rl.l.high = c;
  56    c >>= 32;
  57    c = c + rm.l.high + rn.l.high + rh.l.low;
  58    rh.l.low = c;
  59    rh.l.high += (uint32_t)(c >> 32);
  60
  61    *plow = rl.ll;
  62    *phigh = rh.ll;
  63}
  64
  65/* Unsigned 64x64 -> 128 multiplication */
  66void mulu64 (uint64_t *plow, uint64_t *phigh, uint64_t a, uint64_t b)
  67{
  68    mul64(plow, phigh, a, b);
  69}
  70
  71/* Signed 64x64 -> 128 multiplication */
  72void muls64 (uint64_t *plow, uint64_t *phigh, int64_t a, int64_t b)
  73{
  74    uint64_t rh;
  75
  76    mul64(plow, &rh, a, b);
  77
  78    /* Adjust for signs.  */
  79    if (b < 0) {
  80        rh -= a;
  81    }
  82    if (a < 0) {
  83        rh -= b;
  84    }
  85    *phigh = rh;
  86}
  87
  88/* Unsigned 128x64 division.  Returns 1 if overflow (divide by zero or */
  89/* quotient exceeds 64 bits).  Otherwise returns quotient via plow and */
  90/* remainder via phigh. */
  91int divu128(uint64_t *plow, uint64_t *phigh, uint64_t divisor)
  92{
  93    uint64_t dhi = *phigh;
  94    uint64_t dlo = *plow;
  95    unsigned i;
  96    uint64_t carry = 0;
  97
  98    if (divisor == 0) {
  99        return 1;
 100    } else if (dhi == 0) {
 101        *plow  = dlo / divisor;
 102        *phigh = dlo % divisor;
 103        return 0;
 104    } else if (dhi > divisor) {
 105        return 1;
 106    } else {
 107
 108        for (i = 0; i < 64; i++) {
 109            carry = dhi >> 63;
 110            dhi = (dhi << 1) | (dlo >> 63);
 111            if (carry || (dhi >= divisor)) {
 112                dhi -= divisor;
 113                carry = 1;
 114            } else {
 115                carry = 0;
 116            }
 117            dlo = (dlo << 1) | carry;
 118        }
 119
 120        *plow = dlo;
 121        *phigh = dhi;
 122        return 0;
 123    }
 124}
 125
 126int divs128(int64_t *plow, int64_t *phigh, int64_t divisor)
 127{
 128    int sgn_dvdnd = *phigh < 0;
 129    int sgn_divsr = divisor < 0;
 130    int overflow = 0;
 131
 132    if (sgn_dvdnd) {
 133        *plow = ~(*plow);
 134        *phigh = ~(*phigh);
 135        if (*plow == (int64_t)-1) {
 136            *plow = 0;
 137            (*phigh)++;
 138         } else {
 139            (*plow)++;
 140         }
 141    }
 142
 143    if (sgn_divsr) {
 144        divisor = 0 - divisor;
 145    }
 146
 147    overflow = divu128((uint64_t *)plow, (uint64_t *)phigh, (uint64_t)divisor);
 148
 149    if (sgn_dvdnd  ^ sgn_divsr) {
 150        *plow = 0 - *plow;
 151    }
 152
 153    if (!overflow) {
 154        if ((*plow < 0) ^ (sgn_dvdnd ^ sgn_divsr)) {
 155            overflow = 1;
 156        }
 157    }
 158
 159    return overflow;
 160}
 161
 162