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113 lines
2.9 KiB
C
113 lines
2.9 KiB
C
/* sync.c the Netwide Disassembler synchronisation processing module
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*
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* The Netwide Assembler is copyright (C) 1996 Simon Tatham and
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* Julian Hall. All rights reserved. The software is
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* redistributable under the licence given in the file "Licence"
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* distributed in the NASM archive.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <limits.h>
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#include "sync.h"
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#define SYNC_MAX 4096 /* max # of sync points */
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/*
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* This lot manages the current set of sync points by means of a
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* heap (priority queue) structure.
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*/
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static struct Sync {
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unsigned long pos;
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unsigned long length;
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} *synx;
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static int nsynx;
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void init_sync(void)
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{
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/*
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* I'd like to allocate an array of size SYNC_MAX, then write
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* `synx--' which would allow numbering the array from one
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* instead of zero without wasting memory. Sadly I don't trust
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* this to work in 16-bit Large model, so it's staying the way
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* it is. Btw, we don't care about freeing this array, since it
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* has to last for the duration of the program and will then be
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* auto-freed on exit. And I'm lazy ;-)
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*
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* Speaking of 16-bit Large model, that's also the reason I'm
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* not declaring this array statically - by doing it
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* dynamically I avoid problems with the total size of DGROUP
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* in Borland C.
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*/
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synx = malloc((SYNC_MAX+1) * sizeof(*synx));
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if (!synx) {
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fprintf(stderr, "ndisasm: not enough memory for sync array\n");
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exit(1);
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}
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nsynx = 0;
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}
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void add_sync(unsigned long pos, unsigned long length)
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{
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int i;
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if (nsynx == SYNC_MAX)
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return; /* can't do anything - overflow */
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nsynx++;
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synx[nsynx].pos = pos;
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synx[nsynx].length = length;
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for (i = nsynx; i > 1; i /= 2) {
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if (synx[i/2].pos > synx[i].pos) {
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struct Sync t;
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t = synx[i/2]; /* structure copy */
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synx[i/2] = synx[i]; /* structure copy again */
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synx[i] = t; /* another structure copy */
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}
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}
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}
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unsigned long next_sync(unsigned long position, unsigned long *length)
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{
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while (nsynx > 0 && synx[1].pos + synx[1].length <= position) {
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int i, j;
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struct Sync t;
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t = synx[nsynx]; /* structure copy */
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synx[nsynx] = synx[1]; /* structure copy */
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synx[1] = t; /* ditto */
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nsynx--;
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i = 1;
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while (i*2 <= nsynx) {
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j = i*2;
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if (synx[j].pos < synx[i].pos &&
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(j+1 > nsynx || synx[j+1].pos > synx[j].pos)) {
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t = synx[j]; /* structure copy */
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synx[j] = synx[i]; /* lots of these... */
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synx[i] = t; /* ...aren't there? */
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i = j;
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} else if (j+1 <= nsynx && synx[j+1].pos < synx[i].pos) {
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t = synx[j+1]; /* structure copy */
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synx[j+1] = synx[i]; /* structure <yawn> copy */
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synx[i] = t; /* structure copy <zzzz....> */
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i = j+1;
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} else
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break;
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}
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}
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if (nsynx > 0) {
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if (length)
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*length = synx[1].length;
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return synx[1].pos;
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} else {
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if (length)
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*length = 0L;
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return ULONG_MAX;
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}
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}
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