/*
* Encodes huffman code |sym| into |*dest_ptr|, whose least |rembits|
* bits are not filled yet. The |rembits| must be in range [1, 8],
* inclusive. At the end of the process, the |*dest_ptr| is updated
* and points where next output should be placed. The number of
* unfilled bits in the pointed location is returned.
*/
static ssize_t huff_encode_sym(nghttp2_bufs *bufs, size_t *avail_ptr,
size_t rembits,
const nghttp2_huff_sym *sym)
{
int rv;
size_t nbits = sym->nbits;
for(;;) {
if(rembits > nbits) {
if(*avail_ptr) {
nghttp2_bufs_fast_orb_hold(bufs, sym->code << (rembits - nbits));
} else {
rv = nghttp2_bufs_orb_hold(bufs, sym->code << (rembits - nbits));
if(rv != 0) {
return rv;
}
*avail_ptr = nghttp2_bufs_cur_avail(bufs);
}
rembits -= nbits;
break;
}
if(*avail_ptr) {
nghttp2_bufs_fast_orb(bufs, sym->code >> (nbits - rembits));
--*avail_ptr;
} else {
rv = nghttp2_bufs_orb(bufs, sym->code >> (nbits - rembits));
if(rv != 0) {
return rv;
}
*avail_ptr = nghttp2_bufs_cur_avail(bufs);
}
nbits -= rembits;
rembits = 8;
if(nbits == 0) {
break;
}
if(*avail_ptr) {
nghttp2_bufs_fast_addb_hold(bufs, 0);
} else {
rv = nghttp2_bufs_addb_hold(bufs, 0);
if(rv != 0) {
return rv;
}
*avail_ptr = nghttp2_bufs_cur_avail(bufs);
}
}
/*
* Encodes huffman code |sym| into |*dest_ptr|, whose least |rembits|
* bits are not filled yet. The |rembits| must be in range [1, 8],
* inclusive. At the end of the process, the |*dest_ptr| is updated
* and points where next output should be placed. The number of
* unfilled bits in the pointed location is returned.
*/
static ssize_t huff_encode_sym(nghttp2_bufs *bufs, size_t *avail_ptr,
size_t rembits, const nghttp2_huff_sym *sym) {
int rv;
size_t nbits = sym->nbits;
uint32_t code = sym->code;
/* We assume that sym->nbits <= 32 */
if (rembits > nbits) {
nghttp2_bufs_fast_orb_hold(bufs, code << (rembits - nbits));
return (ssize_t)(rembits - nbits);
}
if (rembits == nbits) {
nghttp2_bufs_fast_orb(bufs, code);
--*avail_ptr;
return 8;
}
nghttp2_bufs_fast_orb(bufs, code >> (nbits - rembits));
--*avail_ptr;
nbits -= rembits;
if (nbits & 0x7) {
/* align code to MSB byte boundary */
code <<= 8 - (nbits & 0x7);
}
/* we lose at most 3 bytes, but it is not critical in practice */
if (*avail_ptr < (nbits + 7) / 8) {
rv = nghttp2_bufs_advance(bufs);
if (rv != 0) {
return rv;
}
*avail_ptr = nghttp2_bufs_cur_avail(bufs);
/* we assume that we at least 3 buffer space available */
assert(*avail_ptr >= 3);
}
/* fast path, since most code is less than 8 */
if (nbits < 8) {
nghttp2_bufs_fast_addb_hold(bufs, code);
*avail_ptr = nghttp2_bufs_cur_avail(bufs);
return (ssize_t)(8 - nbits);
}
/* handle longer code path */
if (nbits > 24) {
nghttp2_bufs_fast_addb(bufs, code >> 24);
nbits -= 8;
}
void test_nghttp2_bufs_addb(void)
{
int rv;
nghttp2_bufs bufs;
ssize_t i;
rv = nghttp2_bufs_init(&bufs, 1000, 3);
CU_ASSERT(0 == rv);
rv = nghttp2_bufs_addb(&bufs, 14);
CU_ASSERT(0 == rv);
CU_ASSERT(1 == nghttp2_buf_len(&bufs.cur->buf));
CU_ASSERT(1 == nghttp2_bufs_len(&bufs));
CU_ASSERT(14 == *bufs.cur->buf.pos);
for(i = 0; i < 999; ++i) {
rv = nghttp2_bufs_addb(&bufs, 254);
CU_ASSERT(0 == rv);
CU_ASSERT(i + 2 == nghttp2_buf_len(&bufs.cur->buf));
CU_ASSERT(i + 2 == nghttp2_bufs_len(&bufs));
CU_ASSERT(254 == *(bufs.cur->buf.last - 1));
CU_ASSERT(bufs.cur == bufs.head);
}
rv = nghttp2_bufs_addb(&bufs, 253);
CU_ASSERT(0 == rv);
CU_ASSERT(1 == nghttp2_buf_len(&bufs.cur->buf));
CU_ASSERT(1001 == nghttp2_bufs_len(&bufs));
CU_ASSERT(253 == *(bufs.cur->buf.last - 1));
CU_ASSERT(bufs.cur == bufs.head->next);
rv = nghttp2_bufs_addb_hold(&bufs, 15);
CU_ASSERT(0 == rv);
CU_ASSERT(1 == nghttp2_buf_len(&bufs.cur->buf));
CU_ASSERT(1001 == nghttp2_bufs_len(&bufs));
CU_ASSERT(15 == *(bufs.cur->buf.last));
/* test fast version */
nghttp2_bufs_fast_addb(&bufs, 240);
CU_ASSERT(2 == nghttp2_buf_len(&bufs.cur->buf));
CU_ASSERT(1002 == nghttp2_bufs_len(&bufs));
CU_ASSERT(240 == *(bufs.cur->buf.last - 1));
nghttp2_bufs_fast_addb_hold(&bufs, 113);
CU_ASSERT(2 == nghttp2_buf_len(&bufs.cur->buf));
CU_ASSERT(1002 == nghttp2_bufs_len(&bufs));
CU_ASSERT(113 == *(bufs.cur->buf.last));
/* addb_hold when last == end */
bufs.cur->buf.last = bufs.cur->buf.end;
rv = nghttp2_bufs_addb_hold(&bufs, 19);
CU_ASSERT(0 == rv);
CU_ASSERT(0 == nghttp2_buf_len(&bufs.cur->buf));
CU_ASSERT(2000 == nghttp2_bufs_len(&bufs));
CU_ASSERT(19 == *(bufs.cur->buf.last));
nghttp2_bufs_free(&bufs);
}
