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 #include <stdio.h>
  41 #include <stdlib.h>
  42 #include <limits.h>
  43 #include <inttypes.h>
  44
  45 #include "nasmlib.h"
  46 #include "sync.h"
  47
  48 #define SYNC_MAX 4096           /* max # of sync points (initial) */
  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     uint32_t pos;
  57     uint32_t length;
  58 } *synx;
  59 static int max_synx, nsynx;
  60
  61 static inline void swap_sync(uint32_t dst, uint32_t src)
  62 {
  63     struct Sync t = synx[dst];
  64     synx[dst] = synx[src];
  65     synx[src] = t;
  66 }
  67
  68 void init_sync(void)
  69 {
  70     max_synx = SYNC_MAX-1;
  71     synx = nasm_malloc(SYNC_MAX * sizeof(*synx));
  72     nsynx = 0;
  73 }
  74
  75 void add_sync(uint32_t pos, uint32_t length)
  76 {
  77     int i;
  78
  79     if (nsynx >= max_synx) {
  80         max_synx = (max_synx << 1)+1;
  81         synx = nasm_realloc(synx, (max_synx+1) * sizeof(*synx));
  82     }
  83
  84     nsynx++;
  85     synx[nsynx].pos = pos;
  86     synx[nsynx].length = length;
  87
  88     for (i = nsynx; i > 1; i /= 2) {
  89         if (synx[i / 2].pos > synx[i].pos)
  90             swap_sync(i / 2, i);
  91     }
  92 }
  93
  94 uint32_t next_sync(uint32_t position, uint32_t *length)
  95 {
  96     while (nsynx > 0 && synx[1].pos + synx[1].length <= position) {
  97         int i, j;
  98
  99         swap_sync(nsynx, 1);
 100         nsynx--;
 101
 102         i = 1;
 103         while (i * 2 <= nsynx) {
 104             j = i * 2;
 105             if (synx[j].pos < synx[i].pos &&
 106                 (j + 1 > nsynx || synx[j + 1].pos > synx[j].pos)) {
 107                 swap_sync(j, i);
 108                 i = j;
 109             } else if (j + 1 <= nsynx && synx[j + 1].pos < synx[i].pos) {
 110                 swap_sync(j + 1, i);
 111                 i = j + 1;
 112             } else
 113                 break;
 114         }
 115     }
 116
 117     if (nsynx > 0) {
 118         if (length)
 119             *length = synx[1].length;
 120         return synx[1].pos;
 121     } else {
 122         if (length)
 123             *length = 0L;
 124         return 0;
 125     }
 126 }