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 <limits.h>
  11
  12 #include "sync.h"
  13
  14 #define SYNC_MAX 4096                  /* max # of sync points */
  15
  16 static struct Sync {
  17     unsigned long pos;
  18     unsigned long length;
  19 } synx[SYNC_MAX];
  20 static int nsynx;
  21
  22 void init_sync(void) {
  23     nsynx = 0;
  24 }
  25
  26 void add_sync(unsigned long pos, unsigned long length) {
  27     int i;
  28
  29     if (nsynx == SYNC_MAX)
  30         return;                        /* can't do anything - overflow */
  31
  32     nsynx++;
  33     synx[nsynx].pos = pos;
  34     synx[nsynx].length = length;
  35
  36     for (i = nsynx; i > 1; i /= 2) {
  37         if (synx[i/2].pos > synx[i].pos) {
  38             struct Sync t;
  39             t = synx[i/2];             /* structure copy */
  40             synx[i/2] = synx[i];       /* structure copy again */
  41             synx[i] = t;               /* another structure copy */
  42         }
  43     }
  44 }
  45
  46 unsigned long next_sync(unsigned long position, unsigned long *length) {
  47     while (nsynx > 0 && synx[1].pos + synx[1].length <= position) {
  48         int i, j;
  49         struct Sync t;
  50         t = synx[nsynx];               /* structure copy */
  51         synx[nsynx] = synx[1];         /* structure copy */
  52         synx[1] = t;                   /* ditto */
  53
  54         nsynx--;
  55
  56         i = 1;
  57         while (i*2 <= nsynx) {
  58             j = i*2;
  59             if (synx[j].pos < synx[i].pos &&
  60                 (j+1 > nsynx || synx[j+1].pos > synx[j].pos)) {
  61                 t = synx[j];           /* structure copy */
  62                 synx[j] = synx[i];     /* lots of these... */
  63                 synx[i] = t;           /* ...aren't there? */
  64                 i = j;
  65             } else if (j+1 <= nsynx && synx[j+1].pos < synx[i].pos) {
  66                 t = synx[j+1];         /* structure copy */
  67                 synx[j+1] = synx[i];   /* structure <yawn> copy */
  68                 synx[i] = t;           /* structure copy <zzzz....> */
  69                 i = j+1;
  70             } else
  71                 break;
  72         }
  73     }
  74
  75     if (nsynx > 0) {
  76         if (length)
  77             *length = synx[1].length;
  78         return synx[1].pos;
  79     } else {
  80         if (length)
  81             *length = 0L;
  82         return ULONG_MAX;
  83     }
  84 }