disp8.c

   1 /* ----------------------------------------------------------------------- *
   2  *
   3  *   Copyright 1996-2013 The NASM Authors - All Rights Reserved
   4  *   See the file AUTHORS included with the NASM distribution for
   5  *   the specific copyright holders.
   6  *
   7  *   Redistribution and use in source and binary forms, with or without
   8  *   modification, are permitted provided that the following
   9  *   conditions are met:
  10  *
  11  *   * Redistributions of source code must retain the above copyright
  12  *     notice, this list of conditions and the following disclaimer.
  13  *   * Redistributions in binary form must reproduce the above
  14  *     copyright notice, this list of conditions and the following
  15  *     disclaimer in the documentation and/or other materials provided
  16  *     with the distribution.
  17  *
  18  *     THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
  19  *     CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
  20  *     INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
  21  *     MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  22  *     DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
  23  *     CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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  25  *     NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  26  *     LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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  29  *     OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
  30  *     EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  31  *
  32  * ----------------------------------------------------------------------- */
  33
  34 /*
  35  * disp8.c   : Contains a common logic for EVEX compressed displacement
  36  */
  37
  38 #include "disp8.h"
  39
  40 /*
  41  * Find N value for compressed displacement (disp8 * N)
  42  */
  43 uint8_t get_disp8N(insn *ins)
  44 {
  45     const uint8_t fv_n[2][2][VLMAX] = {{{16, 32, 64}, {4, 4, 4}},
  46                                        {{16, 32, 64}, {8, 8, 8}}};
  47     const uint8_t hv_n[2][VLMAX]    =  {{8, 16, 32}, {4, 4, 4}};
  48     const uint8_t dup_n[VLMAX]      =   {8, 32, 64};
  49
  50     bool evex_b           = (ins->evex_p[2] & EVEX_P2B) >> 4;
  51     enum ttypes   tuple   = ins->evex_tuple;
  52     enum vectlens vectlen = (ins->evex_p[2] & EVEX_P2LL) >> 5;
  53     bool evex_w           = (ins->evex_p[1] & EVEX_P1W) >> 7;
  54     uint8_t n = 0;
  55
  56     switch(tuple) {
  57     case FV:
  58         n = fv_n[evex_w][evex_b][vectlen];
  59         break;
  60     case HV:
  61         n = hv_n[evex_b][vectlen];
  62         break;
  63
  64     case FVM:
  65         /* 16, 32, 64 for VL 128, 256, 512 respectively*/
  66         n = 1 << (vectlen + 4);
  67         break;
  68     case T1S8:  /* N = 1 */
  69     case T1S16: /* N = 2 */
  70         n = tuple - T1S8 + 1;
  71         break;
  72     case T1S:
  73         /* N = 4 for 32bit, 8 for 64bit */
  74         n = evex_w ? 8 : 4;
  75         break;
  76     case T1F32:
  77     case T1F64:
  78         /* N = 4 for 32bit, 8 for 64bit */
  79         n = (tuple == T1F32 ? 4 : 8);
  80         break;
  81     case T2:
  82     case T4:
  83     case T8:
  84         if (vectlen + 7 <= (evex_w + 5) + (tuple - T2 + 1))
  85             n = 0;
  86         else
  87             n = 1 << (tuple - T2 + evex_w + 3);
  88         break;
  89     case HVM:
  90     case QVM:
  91     case OVM:
  92         n = 1 << (OVM - tuple + vectlen + 1);
  93         break;
  94     case M128:
  95         n = 16;
  96         break;
  97     case DUP:
  98         n = dup_n[vectlen];
  99         break;
 100
 101     default:
 102         break;
 103     }
 104
 105     return n;
 106 }
 107
 108 /*
 109  * Check if offset is a multiple of N with corresponding tuple type
 110  * if Disp8*N is available, compressed displacement is stored in compdisp
 111  */
 112 bool is_disp8n(operand *input, insn *ins, int8_t *compdisp)
 113 {
 114     int32_t off           = input->offset;
 115     uint8_t n;
 116     int32_t disp8;
 117
 118     n = get_disp8N(ins);
 119
 120     if (n && !(off & (n - 1))) {
 121         disp8 = off / n;
 122         /* if it fits in Disp8 */
 123         if (disp8 >= -128 && disp8 <= 127) {
 124             *compdisp = disp8;
 125             return true;
 126         }
 127     }
 128
 129     *compdisp = 0;
 130     return false;
 131 }