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