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 */
  30 static 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 */
  66 void 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 */
  72 void 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. */
  91 int 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
 126 int 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