Function create_delta

diff-delta.c:319–510

#define MAX_OP_SIZE	(5 + 5 + 1 + RABIN_WINDOW + 7)

void *
create_delta(const struct delta_index *index,
	     const void *trg_buf, unsigned long trg_size,
	     unsigned long *delta_size, unsigned long max_size)
{
	unsigned int i, val;
	off_t outpos, moff;
	size_t l, outsize, msize;
	int inscnt;
	const unsigned char *ref_data, *ref_top, *data, *top;
	unsigned char *out;

	*delta_size = 0;

	if (!trg_buf || !trg_size)
		return NULL;

	outpos = 0;
	outsize = 8192;
	if (max_size && outsize >= max_size)
		outsize = max_size + MAX_OP_SIZE + 1;
	out = malloc(outsize);
	if (!out)
		return NULL;

	/* store reference buffer size */
	l = index->src_size;
	while (l >= 0x80) {
		out[outpos++] = l | 0x80;
		l >>= 7;
	}
	out[outpos++] = l;

	/* store target buffer size */
	l = trg_size;
	while (l >= 0x80) {
		out[outpos++] = l | 0x80;
		l >>= 7;
	}
	out[outpos++] = l;

	ref_data = index->src_buf;
	ref_top = ref_data + index->src_size;
	data = trg_buf;
	top = (const unsigned char *) trg_buf + trg_size;

	outpos++;
	val = 0;
	for (i = 0; i < RABIN_WINDOW && data < top; i++, data++) {
		out[outpos++] = *data;
		val = ((val << 8) | *data) ^ T[val >> RABIN_SHIFT];
	}
	inscnt = i;

	moff = 0;
	msize = 0;
	while (data < top) {
		if (msize < 4096) {