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_SHIFT          31
  49 #define SYNC_MAX_SIZE           (1U << SYNC_MAX_SHIFT)
  50
  51 /* initial # of sync points (*must* be power of two)*/
  52 #define SYNC_INITIAL_CHUNK      (1U << 12)
  53
  54 /*
  55  * This lot manages the current set of sync points by means of a
  56  * heap (priority queue) structure.
  57  */
  58
  59 static struct Sync {
  60     uint32_t pos;
  61     uint32_t length;
  62 } *synx;
  63
  64 static uint32_t max_synx, nsynx;
  65
  66 static inline void swap_sync(uint32_t dst, uint32_t src)
  67 {
  68     struct Sync t = synx[dst];
  69     synx[dst] = synx[src];
  70     synx[src] = t;
  71 }
  72
  73 void init_sync(void)
  74 {
  75     max_synx = SYNC_INITIAL_CHUNK;
  76     synx = nasm_malloc((max_synx + 1) * sizeof(*synx));
  77     nsynx = 0;
  78 }
  79
  80 void add_sync(uint32_t pos, uint32_t length)
  81 {
  82     uint32_t i;
  83
  84     if (nsynx >= max_synx) {
  85         if (max_synx >= SYNC_MAX_SIZE) /* too many sync points! */
  86             return;
  87         max_synx = (max_synx << 1);
  88         synx = nasm_realloc(synx, (max_synx + 1) * sizeof(*synx));
  89     }
  90
  91     nsynx++;
  92     synx[nsynx].pos = pos;
  93     synx[nsynx].length = length;
  94
  95     for (i = nsynx; i > 1; i /= 2) {
  96         if (synx[i / 2].pos > synx[i].pos)
  97             swap_sync(i / 2, i);
  98     }
  99 }
 100
 101 uint32_t next_sync(uint32_t position, uint32_t *length)
 102 {
 103     while (nsynx > 0 && synx[1].pos + synx[1].length <= position) {
 104         uint32_t i, j;
 105
 106         swap_sync(nsynx, 1);
 107         nsynx--;
 108
 109         i = 1;
 110         while (i * 2 <= nsynx) {
 111             j = i * 2;
 112             if (synx[j].pos < synx[i].pos &&
 113                 (j + 1 > nsynx || synx[j + 1].pos > synx[j].pos)) {
 114                 swap_sync(j, i);
 115                 i = j;
 116             } else if (j + 1 <= nsynx && synx[j + 1].pos < synx[i].pos) {
 117                 swap_sync(j + 1, i);
 118                 i = j + 1;
 119             } else
 120                 break;
 121         }
 122     }
 123
 124     if (nsynx > 0) {
 125         if (length)
 126             *length = synx[1].length;
 127         return synx[1].pos;
 128     } else {
 129         if (length)
 130             *length = 0L;
 131         return 0;
 132     }
 133 }