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 "compiler.h"
  10
  11 #include <stdio.h>
  12 #include <stdlib.h>
  13 #include <limits.h>
  14 #include <inttypes.h>
  15
  16 #include "nasmlib.h"
  17 #include "sync.h"
  18
  19 #define SYNC_MAX 4096           /* max # of sync points (initial) */
  20
  21 /*
  22  * This lot manages the current set of sync points by means of a
  23  * heap (priority queue) structure.
  24  */
  25
  26 static struct Sync {
  27     uint32_t pos;
  28     uint32_t length;
  29 } *synx;
  30 static int max_synx, nsynx;
  31
  32 void init_sync(void)
  33 {
  34     max_synx = SYNC_MAX-1;
  35     synx = nasm_malloc(SYNC_MAX * sizeof(*synx));
  36     nsynx = 0;
  37 }
  38
  39 void add_sync(uint32_t pos, uint32_t length)
  40 {
  41     int i;
  42
  43     if (nsynx >= max_synx) {
  44         max_synx = (max_synx << 1)+1;
  45         synx = nasm_realloc(synx, (max_synx+1) * sizeof(*synx));
  46     }
  47
  48     nsynx++;
  49     synx[nsynx].pos = pos;
  50     synx[nsynx].length = length;
  51
  52     for (i = nsynx; i > 1; i /= 2) {
  53         if (synx[i / 2].pos > synx[i].pos) {
  54             struct Sync t;
  55             t = synx[i / 2];    /* structure copy */
  56             synx[i / 2] = synx[i];      /* structure copy again */
  57             synx[i] = t;        /* another structure copy */
  58         }
  59     }
  60 }
  61
  62 uint32_t next_sync(uint32_t position, uint32_t *length)
  63 {
  64     while (nsynx > 0 && synx[1].pos + synx[1].length <= position) {
  65         int i, j;
  66         struct Sync t;
  67         t = synx[nsynx];        /* structure copy */
  68         synx[nsynx] = synx[1];  /* structure copy */
  69         synx[1] = t;            /* ditto */
  70
  71         nsynx--;
  72
  73         i = 1;
  74         while (i * 2 <= nsynx) {
  75             j = i * 2;
  76             if (synx[j].pos < synx[i].pos &&
  77                 (j + 1 > nsynx || synx[j + 1].pos > synx[j].pos)) {
  78                 t = synx[j];    /* structure copy */
  79                 synx[j] = synx[i];      /* lots of these... */
  80                 synx[i] = t;    /* ...aren't there? */
  81                 i = j;
  82             } else if (j + 1 <= nsynx && synx[j + 1].pos < synx[i].pos) {
  83                 t = synx[j + 1];        /* structure copy */
  84                 synx[j + 1] = synx[i];  /* structure <yawn> copy */
  85                 synx[i] = t;    /* structure copy <zzzz....> */
  86                 i = j + 1;
  87             } else
  88                 break;
  89         }
  90     }
  91
  92     if (nsynx > 0) {
  93         if (length)
  94             *length = synx[1].length;
  95         return synx[1].pos;
  96     } else {
  97         if (length)
  98             *length = 0L;
  99         return UINT32_MAX;
 100     }
 101 }