disasm/sync.c

   1 /* ----------------------------------------------------------------------- *
   2  *
   3  *   Copyright 1996-2009 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,
  24  *     SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  25  *     NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  26  *     LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  *     HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  28  *     CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
  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  * sync.c   the Netwide Disassembler synchronisation processing module
  36  */
  37
  38 #include "compiler.h"
  39
  40
  41 #include "nasmlib.h"
  42 #include "sync.h"
  43
  44 #define SYNC_MAX_SHIFT          31
  45 #define SYNC_MAX_SIZE           (1U << SYNC_MAX_SHIFT)
  46
  47 /* initial # of sync points (*must* be power of two)*/
  48 #define SYNC_INITIAL_CHUNK      (1U << 12)
  49
  50 /*
  51  * This lot manages the current set of sync points by means of a
  52  * heap (priority queue) structure.
  53  */
  54
  55 static struct Sync {
  56     uint64_t pos;
  57     uint32_t length;
  58 } *synx;
  59
  60 static uint32_t max_synx, nsynx;
  61
  62 static inline void swap_sync(uint32_t dst, uint32_t src)
  63 {
  64     struct Sync t = synx[dst];
  65     synx[dst] = synx[src];
  66     synx[src] = t;
  67 }
  68
  69 void init_sync(void)
  70 {
  71     max_synx = SYNC_INITIAL_CHUNK;
  72     synx = nasm_malloc((max_synx + 1) * sizeof(*synx));
  73     nsynx = 0;
  74 }
  75
  76 void add_sync(uint64_t pos, uint32_t length)
  77 {
  78     uint32_t i;
  79
  80     if (nsynx >= max_synx) {
  81         if (max_synx >= SYNC_MAX_SIZE) /* too many sync points! */
  82             return;
  83         max_synx = (max_synx << 1);
  84         synx = nasm_realloc(synx, (max_synx + 1) * sizeof(*synx));
  85     }
  86
  87     nsynx++;
  88     synx[nsynx].pos = pos;
  89     synx[nsynx].length = length;
  90
  91     for (i = nsynx; i > 1; i /= 2) {
  92         if (synx[i / 2].pos > synx[i].pos)
  93             swap_sync(i / 2, i);
  94     }
  95 }
  96
  97 uint64_t next_sync(uint64_t position, uint32_t *length)
  98 {
  99     while (nsynx > 0 && synx[1].pos + synx[1].length <= position) {
 100         uint32_t i, j;
 101
 102         swap_sync(nsynx, 1);
 103         nsynx--;
 104
 105         i = 1;
 106         while (i * 2 <= nsynx) {
 107             j = i * 2;
 108             if (synx[j].pos < synx[i].pos &&
 109                 (j + 1 > nsynx || synx[j + 1].pos > synx[j].pos)) {
 110                 swap_sync(j, i);
 111                 i = j;
 112             } else if (j + 1 <= nsynx && synx[j + 1].pos < synx[i].pos) {
 113                 swap_sync(j + 1, i);
 114                 i = j + 1;
 115             } else
 116                 break;
 117         }
 118     }
 119
 120     if (nsynx > 0) {
 121         if (length)
 122             *length = synx[1].length;
 123         return synx[1].pos;
 124     } else {
 125         if (length)
 126             *length = 0L;
 127         return 0;
 128     }
 129 }