in windows/CodePush/miniz/miniz.c [1711:1854]
static mz_bool tdefl_compress_normal(tdefl_compressor *d)
{
const mz_uint8 *pSrc = d->m_pSrc;
size_t src_buf_left = d->m_src_buf_left;
tdefl_flush flush = d->m_flush;
while ((src_buf_left) || ((flush) && (d->m_lookahead_size)))
{
mz_uint len_to_move, cur_match_dist, cur_match_len, cur_pos;
/* Update dictionary and hash chains. Keeps the lookahead size equal to TDEFL_MAX_MATCH_LEN. */
if ((d->m_lookahead_size + d->m_dict_size) >= (TDEFL_MIN_MATCH_LEN - 1))
{
mz_uint dst_pos = (d->m_lookahead_pos + d->m_lookahead_size) & TDEFL_LZ_DICT_SIZE_MASK, ins_pos = d->m_lookahead_pos + d->m_lookahead_size - 2;
mz_uint hash = (d->m_dict[ins_pos & TDEFL_LZ_DICT_SIZE_MASK] << TDEFL_LZ_HASH_SHIFT) ^ d->m_dict[(ins_pos + 1) & TDEFL_LZ_DICT_SIZE_MASK];
mz_uint num_bytes_to_process = (mz_uint)MZ_MIN(src_buf_left, TDEFL_MAX_MATCH_LEN - d->m_lookahead_size);
const mz_uint8 *pSrc_end = pSrc + num_bytes_to_process;
src_buf_left -= num_bytes_to_process;
d->m_lookahead_size += num_bytes_to_process;
while (pSrc != pSrc_end)
{
mz_uint8 c = *pSrc++;
d->m_dict[dst_pos] = c;
if (dst_pos < (TDEFL_MAX_MATCH_LEN - 1))
d->m_dict[TDEFL_LZ_DICT_SIZE + dst_pos] = c;
hash = ((hash << TDEFL_LZ_HASH_SHIFT) ^ c) & (TDEFL_LZ_HASH_SIZE - 1);
d->m_next[ins_pos & TDEFL_LZ_DICT_SIZE_MASK] = d->m_hash[hash];
d->m_hash[hash] = (mz_uint16)(ins_pos);
dst_pos = (dst_pos + 1) & TDEFL_LZ_DICT_SIZE_MASK;
ins_pos++;
}
}
else
{
while ((src_buf_left) && (d->m_lookahead_size < TDEFL_MAX_MATCH_LEN))
{
mz_uint8 c = *pSrc++;
mz_uint dst_pos = (d->m_lookahead_pos + d->m_lookahead_size) & TDEFL_LZ_DICT_SIZE_MASK;
src_buf_left--;
d->m_dict[dst_pos] = c;
if (dst_pos < (TDEFL_MAX_MATCH_LEN - 1))
d->m_dict[TDEFL_LZ_DICT_SIZE + dst_pos] = c;
if ((++d->m_lookahead_size + d->m_dict_size) >= TDEFL_MIN_MATCH_LEN)
{
mz_uint ins_pos = d->m_lookahead_pos + (d->m_lookahead_size - 1) - 2;
mz_uint hash = ((d->m_dict[ins_pos & TDEFL_LZ_DICT_SIZE_MASK] << (TDEFL_LZ_HASH_SHIFT * 2)) ^ (d->m_dict[(ins_pos + 1) & TDEFL_LZ_DICT_SIZE_MASK] << TDEFL_LZ_HASH_SHIFT) ^ c) & (TDEFL_LZ_HASH_SIZE - 1);
d->m_next[ins_pos & TDEFL_LZ_DICT_SIZE_MASK] = d->m_hash[hash];
d->m_hash[hash] = (mz_uint16)(ins_pos);
}
}
}
d->m_dict_size = MZ_MIN(TDEFL_LZ_DICT_SIZE - d->m_lookahead_size, d->m_dict_size);
if ((!flush) && (d->m_lookahead_size < TDEFL_MAX_MATCH_LEN))
break;
/* Simple lazy/greedy parsing state machine. */
len_to_move = 1;
cur_match_dist = 0;
cur_match_len = d->m_saved_match_len ? d->m_saved_match_len : (TDEFL_MIN_MATCH_LEN - 1);
cur_pos = d->m_lookahead_pos & TDEFL_LZ_DICT_SIZE_MASK;
if (d->m_flags & (TDEFL_RLE_MATCHES | TDEFL_FORCE_ALL_RAW_BLOCKS))
{
if ((d->m_dict_size) && (!(d->m_flags & TDEFL_FORCE_ALL_RAW_BLOCKS)))
{
mz_uint8 c = d->m_dict[(cur_pos - 1) & TDEFL_LZ_DICT_SIZE_MASK];
cur_match_len = 0;
while (cur_match_len < d->m_lookahead_size)
{
if (d->m_dict[cur_pos + cur_match_len] != c)
break;
cur_match_len++;
}
if (cur_match_len < TDEFL_MIN_MATCH_LEN)
cur_match_len = 0;
else
cur_match_dist = 1;
}
}
else
{
tdefl_find_match(d, d->m_lookahead_pos, d->m_dict_size, d->m_lookahead_size, &cur_match_dist, &cur_match_len);
}
if (((cur_match_len == TDEFL_MIN_MATCH_LEN) && (cur_match_dist >= 8U * 1024U)) || (cur_pos == cur_match_dist) || ((d->m_flags & TDEFL_FILTER_MATCHES) && (cur_match_len <= 5)))
{
cur_match_dist = cur_match_len = 0;
}
if (d->m_saved_match_len)
{
if (cur_match_len > d->m_saved_match_len)
{
tdefl_record_literal(d, (mz_uint8)d->m_saved_lit);
if (cur_match_len >= 128)
{
tdefl_record_match(d, cur_match_len, cur_match_dist);
d->m_saved_match_len = 0;
len_to_move = cur_match_len;
}
else
{
d->m_saved_lit = d->m_dict[cur_pos];
d->m_saved_match_dist = cur_match_dist;
d->m_saved_match_len = cur_match_len;
}
}
else
{
tdefl_record_match(d, d->m_saved_match_len, d->m_saved_match_dist);
len_to_move = d->m_saved_match_len - 1;
d->m_saved_match_len = 0;
}
}
else if (!cur_match_dist)
tdefl_record_literal(d, d->m_dict[MZ_MIN(cur_pos, sizeof(d->m_dict) - 1)]);
else if ((d->m_greedy_parsing) || (d->m_flags & TDEFL_RLE_MATCHES) || (cur_match_len >= 128))
{
tdefl_record_match(d, cur_match_len, cur_match_dist);
len_to_move = cur_match_len;
}
else
{
d->m_saved_lit = d->m_dict[MZ_MIN(cur_pos, sizeof(d->m_dict) - 1)];
d->m_saved_match_dist = cur_match_dist;
d->m_saved_match_len = cur_match_len;
}
/* Move the lookahead forward by len_to_move bytes. */
d->m_lookahead_pos += len_to_move;
MZ_ASSERT(d->m_lookahead_size >= len_to_move);
d->m_lookahead_size -= len_to_move;
d->m_dict_size = MZ_MIN(d->m_dict_size + len_to_move, (mz_uint)TDEFL_LZ_DICT_SIZE);
/* Check if it's time to flush the current LZ codes to the internal output buffer. */
if ((d->m_pLZ_code_buf > &d->m_lz_code_buf[TDEFL_LZ_CODE_BUF_SIZE - 8]) ||
((d->m_total_lz_bytes > 31 * 1024) && (((((mz_uint)(d->m_pLZ_code_buf - d->m_lz_code_buf) * 115) >> 7) >= d->m_total_lz_bytes) || (d->m_flags & TDEFL_FORCE_ALL_RAW_BLOCKS))))
{
int n;
d->m_pSrc = pSrc;
d->m_src_buf_left = src_buf_left;
if ((n = tdefl_flush_block(d, 0)) != 0)
return (n < 0) ? MZ_FALSE : MZ_TRUE;
}
}
d->m_pSrc = pSrc;
d->m_src_buf_left = src_buf_left;
return MZ_TRUE;
}