sync.c

   1 /* sync.c   the Netwide Disassembler synchronisation processing module
   2  *
   3  * The Netwide Assembler is copyright (C) 1996 Simon Tatham and
   4  * Julian Hall. All rights reserved. The software is
   5  * redistributable under the licence given in the file "Licence"
   6  * distributed in the NASM archive.
   7  */
   8
   9 #include <stdio.h>
  10 #include <stdlib.h>
  11 #include <limits.h>
  12 #include <inttypes.h>
  13
  14 #include "nasmlib.h"
  15 #include "sync.h"
  16
  17 #define SYNC_MAX 4096           /* max # of sync points (initial) */
  18
  19 /*
  20  * This lot manages the current set of sync points by means of a
  21  * heap (priority queue) structure.
  22  */
  23
  24 static struct Sync {
  25     uint32_t pos;
  26     uint32_t length;
  27 } *synx;
  28 static int max_synx, nsynx;
  29
  30 void init_sync(void)
  31 {
  32     max_synx = SYNC_MAX-1;
  33     synx = nasm_malloc(SYNC_MAX * sizeof(*synx));
  34     nsynx = 0;
  35 }
  36
  37 void add_sync(uint32_t pos, uint32_t length)
  38 {
  39     int i;
  40
  41     if (nsynx >= max_synx) {
  42         max_synx = (max_synx << 1)+1;
  43         synx = nasm_realloc(synx, (max_synx+1) * sizeof(*synx));
  44     }
  45
  46     nsynx++;
  47     synx[nsynx].pos = pos;
  48     synx[nsynx].length = length;
  49
  50     for (i = nsynx; i > 1; i /= 2) {
  51         if (synx[i / 2].pos > synx[i].pos) {
  52             struct Sync t;
  53             t = synx[i / 2];    /* structure copy */
  54             synx[i / 2] = synx[i];      /* structure copy again */
  55             synx[i] = t;        /* another structure copy */
  56         }
  57     }
  58 }
  59
  60 uint32_t next_sync(uint32_t position, uint32_t *length)
  61 {
  62     while (nsynx > 0 && synx[1].pos + synx[1].length <= position) {
  63         int i, j;
  64         struct Sync t;
  65         t = synx[nsynx];        /* structure copy */
  66         synx[nsynx] = synx[1];  /* structure copy */
  67         synx[1] = t;            /* ditto */
  68
  69         nsynx--;
  70
  71         i = 1;
  72         while (i * 2 <= nsynx) {
  73             j = i * 2;
  74             if (synx[j].pos < synx[i].pos &&
  75                 (j + 1 > nsynx || synx[j + 1].pos > synx[j].pos)) {
  76                 t = synx[j];    /* structure copy */
  77                 synx[j] = synx[i];      /* lots of these... */
  78                 synx[i] = t;    /* ...aren't there? */
  79                 i = j;
  80             } else if (j + 1 <= nsynx && synx[j + 1].pos < synx[i].pos) {
  81                 t = synx[j + 1];        /* structure copy */
  82                 synx[j + 1] = synx[i];  /* structure <yawn> copy */
  83                 synx[i] = t;    /* structure copy <zzzz....> */
  84                 i = j + 1;
  85             } else
  86                 break;
  87         }
  88     }
  89
  90     if (nsynx > 0) {
  91         if (length)
  92             *length = synx[1].length;
  93         return synx[1].pos;
  94     } else {
  95         if (length)
  96             *length = 0L;
  97         return UINT32_MAX;
  98     }
  99 }