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H. Peter Anvinea6e34d2002-04-30 20:51:32 +00001/* 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>
H. Peter Anvin6768eb72002-04-30 20:52:26 +000010#include <stdlib.h>
H. Peter Anvinea6e34d2002-04-30 20:51:32 +000011#include <limits.h>
12
13#include "sync.h"
14
15#define SYNC_MAX 4096 /* max # of sync points */
16
H. Peter Anvind7ed89e2002-04-30 20:52:08 +000017/*
18 * This lot manages the current set of sync points by means of a
19 * heap (priority queue) structure.
20 */
21
H. Peter Anvinea6e34d2002-04-30 20:51:32 +000022static struct Sync {
23 unsigned long pos;
24 unsigned long length;
H. Peter Anvin6768eb72002-04-30 20:52:26 +000025} *synx;
H. Peter Anvinea6e34d2002-04-30 20:51:32 +000026static int nsynx;
27
28void init_sync(void) {
H. Peter Anvin6768eb72002-04-30 20:52:26 +000029 /*
30 * I'd like to allocate an array of size SYNC_MAX, then write
31 * `synx--' which would allow numbering the array from one
32 * instead of zero without wasting memory. Sadly I don't trust
33 * this to work in 16-bit Large model, so it's staying the way
34 * it is. Btw, we don't care about freeing this array, since it
35 * has to last for the duration of the program and will then be
36 * auto-freed on exit. And I'm lazy ;-)
37 *
38 * Speaking of 16-bit Large model, that's also the reason I'm
39 * not declaring this array statically - by doing it
40 * dynamically I avoid problems with the total size of DGROUP
41 * in Borland C.
42 */
43 synx = malloc((SYNC_MAX+1) * sizeof(*synx));
44 if (!synx) {
45 fprintf(stderr, "ndisasm: not enough memory for sync array\n");
46 exit(1);
47 }
H. Peter Anvinea6e34d2002-04-30 20:51:32 +000048 nsynx = 0;
49}
50
51void add_sync(unsigned long pos, unsigned long length) {
52 int i;
53
54 if (nsynx == SYNC_MAX)
55 return; /* can't do anything - overflow */
56
57 nsynx++;
58 synx[nsynx].pos = pos;
59 synx[nsynx].length = length;
60
61 for (i = nsynx; i > 1; i /= 2) {
62 if (synx[i/2].pos > synx[i].pos) {
63 struct Sync t;
64 t = synx[i/2]; /* structure copy */
65 synx[i/2] = synx[i]; /* structure copy again */
66 synx[i] = t; /* another structure copy */
67 }
68 }
69}
70
71unsigned long next_sync(unsigned long position, unsigned long *length) {
72 while (nsynx > 0 && synx[1].pos + synx[1].length <= position) {
73 int i, j;
74 struct Sync t;
75 t = synx[nsynx]; /* structure copy */
76 synx[nsynx] = synx[1]; /* structure copy */
77 synx[1] = t; /* ditto */
78
79 nsynx--;
80
81 i = 1;
82 while (i*2 <= nsynx) {
83 j = i*2;
84 if (synx[j].pos < synx[i].pos &&
85 (j+1 > nsynx || synx[j+1].pos > synx[j].pos)) {
86 t = synx[j]; /* structure copy */
87 synx[j] = synx[i]; /* lots of these... */
88 synx[i] = t; /* ...aren't there? */
89 i = j;
90 } else if (j+1 <= nsynx && synx[j+1].pos < synx[i].pos) {
91 t = synx[j+1]; /* structure copy */
92 synx[j+1] = synx[i]; /* structure <yawn> copy */
93 synx[i] = t; /* structure copy <zzzz....> */
94 i = j+1;
95 } else
96 break;
97 }
98 }
99
100 if (nsynx > 0) {
101 if (length)
102 *length = synx[1].length;
103 return synx[1].pos;
104 } else {
105 if (length)
106 *length = 0L;
107 return ULONG_MAX;
108 }
109}