static void test_uleb(void)
{
uint32_t i, val;
uint8_t buf[2];
int encode_ret, decode_ret;
for (i = 0; i <= 0x3fff; i++) {
encode_ret = uleb128_encode_small(&buf[0], i);
decode_ret = uleb128_decode_small(&buf[0], &val);
g_assert(encode_ret == decode_ret);
g_assert(i == val);
}
/* decode invalid value */
buf[0] = 0x80;
buf[1] = 0x80;
decode_ret = uleb128_decode_small(&buf[0], &val);
g_assert(decode_ret == -1);
g_assert(val == 0);
}
static void test_encode_decode_1_byte(void)
{
uint8_t *buffer = g_malloc0(PAGE_SIZE);
uint8_t *test = g_malloc0(PAGE_SIZE);
uint8_t *compressed = g_malloc(PAGE_SIZE);
int dlen = 0, rc = 0;
uint8_t buf[2];
test[PAGE_SIZE - 1] = 1;
dlen = xbzrle_encode_buffer(buffer, test, PAGE_SIZE, compressed,
PAGE_SIZE);
g_assert(dlen == (uleb128_encode_small(&buf[0], 4095) + 2));
rc = xbzrle_decode_buffer(compressed, dlen, buffer, PAGE_SIZE);
g_assert(rc == PAGE_SIZE);
g_assert(memcmp(test, buffer, PAGE_SIZE) == 0);
g_free(buffer);
g_free(compressed);
g_free(test);
}
/*
page = zrun nzrun
| zrun nzrun page
zrun = length
nzrun = length byte...
length = uleb128 encoded integer
*/
int xbzrle_encode_buffer(uint8_t *old_buf, uint8_t *new_buf, int slen,
uint8_t *dst, int dlen)
{
uint32_t zrun_len = 0, nzrun_len = 0;
int d = 0, i = 0;
long res;
uint8_t *nzrun_start = NULL;
g_assert(!(((uintptr_t)old_buf | (uintptr_t)new_buf | slen) %
sizeof(long)));
while (i < slen) {
/* overflow */
if (d + 2 > dlen) {
return -1;
}
/* not aligned to sizeof(long) */
res = (slen - i) % sizeof(long);
while (res && old_buf[i] == new_buf[i]) {
zrun_len++;
i++;
res--;
}
/* word at a time for speed */
if (!res) {
while (i < slen &&
(*(long *)(old_buf + i)) == (*(long *)(new_buf + i))) {
i += sizeof(long);
zrun_len += sizeof(long);
}
/* go over the rest */
while (i < slen && old_buf[i] == new_buf[i]) {
zrun_len++;
i++;
}
}
/* buffer unchanged */
if (zrun_len == slen) {
return 0;
}
/* skip last zero run */
if (i == slen) {
return d;
}
d += uleb128_encode_small(dst + d, zrun_len);
zrun_len = 0;
nzrun_start = new_buf + i;
/* overflow */
if (d + 2 > dlen) {
return -1;
}
/* not aligned to sizeof(long) */
res = (slen - i) % sizeof(long);
while (res && old_buf[i] != new_buf[i]) {
i++;
nzrun_len++;
res--;
}
/* word at a time for speed, use of 32-bit long okay */
if (!res) {
/* truncation to 32-bit long okay */
unsigned long mask = (unsigned long)0x0101010101010101ULL;
while (i < slen) {
unsigned long xor;
xor = *(unsigned long *)(old_buf + i)
^ *(unsigned long *)(new_buf + i);
if ((xor - mask) & ~xor & (mask << 7)) {
/* found the end of an nzrun within the current long */
while (old_buf[i] != new_buf[i]) {
nzrun_len++;
i++;
}
break;
} else {
i += sizeof(long);
nzrun_len += sizeof(long);
}
}
}
d += uleb128_encode_small(dst + d, nzrun_len);
/* overflow */
if (d + nzrun_len > dlen) {
return -1;
}
memcpy(dst + d, nzrun_start, nzrun_len);
d += nzrun_len;
nzrun_len = 0;
}
return d;
}
