cuberite/libdeflate
1
0
Fork 0
mirror of https://github.com/cuberite/libdeflate.git synced 2025-08-03 09:46:04 -04:00
Code Issues Packages Projects Releases Wiki Activity

deflate_compress: factor out deflate_write_match()

Browse Source 
Reduce code duplication between deflate_write_sequences() and
deflate_write_item_list().
This commit is contained in:
Eric Biggers 2022-01-20 23:36:02 -08:00
parent 90e7211d39
commit 194f6a447f
1 changed files with 50 additions and 84 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

134
lib/deflate_compress.c
View File

@ -1703,6 +1703,45 @@ deflate_write_literal_run(struct deflate_output_bitstream *os,
#endif
}
static forceinline void
deflate_write_match(struct deflate_output_bitstream * restrict os,
unsigned length, unsigned length_slot,
unsigned offset, unsigned offset_symbol,
const struct deflate_codes * restrict codes)
{
unsigned litlen_symbol = DEFLATE_FIRST_LEN_SYM + length_slot;
/* Litlen symbol */
deflate_add_bits(os, codes->codewords.litlen[litlen_symbol],
codes->lens.litlen[litlen_symbol]);
/* Extra length bits */
STATIC_ASSERT(CAN_BUFFER(MAX_LITLEN_CODEWORD_LEN +
DEFLATE_MAX_EXTRA_LENGTH_BITS));
deflate_add_bits(os, length - deflate_length_slot_base[length_slot],
deflate_extra_length_bits[length_slot]);
if (!CAN_BUFFER(MAX_LITLEN_CODEWORD_LEN +
DEFLATE_MAX_EXTRA_LENGTH_BITS +
MAX_OFFSET_CODEWORD_LEN +
DEFLATE_MAX_EXTRA_OFFSET_BITS))
deflate_flush_bits(os);
/* Offset symbol */
deflate_add_bits(os, codes->codewords.offset[offset_symbol],
codes->lens.offset[offset_symbol]);
if (!CAN_BUFFER(MAX_OFFSET_CODEWORD_LEN +
DEFLATE_MAX_EXTRA_OFFSET_BITS))
deflate_flush_bits(os);
/* Extra offset bits */
deflate_add_bits(os, offset - deflate_offset_slot_base[offset_symbol],
deflate_extra_offset_bits[offset_symbol]);
deflate_flush_bits(os);
}
static void
deflate_write_sequences(struct deflate_output_bitstream * restrict os,
const struct deflate_codes * restrict codes,
@ -1714,9 +1753,6 @@ deflate_write_sequences(struct deflate_output_bitstream * restrict os,
for (;;) {
u32 litrunlen = seq->litrunlen_and_length & SEQ_LITRUNLEN_MASK;
unsigned length = seq->litrunlen_and_length >> SEQ_LENGTH_SHIFT;
unsigned length_slot;
unsigned litlen_symbol;
unsigned offset_symbol;
if (litrunlen) {
deflate_write_literal_run(os, in_next, litrunlen,
@ -1727,44 +1763,10 @@ deflate_write_sequences(struct deflate_output_bitstream * restrict os,
if (length == 0)
return;
deflate_write_match(os, length, seq->length_slot,
seq->offset, seq->offset_symbol, codes);
in_next += length;
length_slot = seq->length_slot;
litlen_symbol = DEFLATE_FIRST_LEN_SYM + length_slot;
/* Litlen symbol */
deflate_add_bits(os, codes->codewords.litlen[litlen_symbol],
codes->lens.litlen[litlen_symbol]);
/* Extra length bits */
STATIC_ASSERT(CAN_BUFFER(MAX_LITLEN_CODEWORD_LEN +
DEFLATE_MAX_EXTRA_LENGTH_BITS));
deflate_add_bits(os,
length - deflate_length_slot_base[length_slot],
deflate_extra_length_bits[length_slot]);
if (!CAN_BUFFER(MAX_LITLEN_CODEWORD_LEN +
DEFLATE_MAX_EXTRA_LENGTH_BITS +
MAX_OFFSET_CODEWORD_LEN +
DEFLATE_MAX_EXTRA_OFFSET_BITS))
deflate_flush_bits(os);
/* Offset symbol */
offset_symbol = seq->offset_symbol;
deflate_add_bits(os, codes->codewords.offset[offset_symbol],
codes->lens.offset[offset_symbol]);
if (!CAN_BUFFER(MAX_OFFSET_CODEWORD_LEN +
DEFLATE_MAX_EXTRA_OFFSET_BITS))
deflate_flush_bits(os);
/* Extra offset bits */
deflate_add_bits(os, seq->offset -
deflate_offset_slot_base[offset_symbol],
deflate_extra_offset_bits[offset_symbol]);
deflate_flush_bits(os);
seq++;
}
}
@ -1774,10 +1776,6 @@ deflate_write_sequences(struct deflate_output_bitstream * restrict os,
* Follow the minimum-cost path in the graph of possible match/literal choices
* for the current block and write out the matches/literals using the specified
* Huffman codes.
*
* Note: this is slightly duplicated with deflate_write_sequences(), the reason
* being that we don't want to waste time translating between intermediate
* match/literal representations.
*/
static void
deflate_write_item_list(struct deflate_output_bitstream *os,
@ -1791,51 +1789,19 @@ deflate_write_item_list(struct deflate_output_bitstream *os,
do {
unsigned length = cur_node->item & OPTIMUM_LEN_MASK;
unsigned offset = cur_node->item >> OPTIMUM_OFFSET_SHIFT;
unsigned litlen_symbol;
unsigned length_slot;
unsigned offset_slot;
if (length == 1) {
/* Literal */
litlen_symbol = offset;
deflate_add_bits(os,
codes->codewords.litlen[litlen_symbol],
codes->lens.litlen[litlen_symbol]);
deflate_add_bits(os, codes->codewords.litlen[offset],
codes->lens.litlen[offset]);
deflate_flush_bits(os);
} else {
/* Match length */
length_slot = deflate_length_slot[length];
litlen_symbol = DEFLATE_FIRST_LEN_SYM + length_slot;
deflate_add_bits(os,
codes->codewords.litlen[litlen_symbol],
codes->lens.litlen[litlen_symbol]);
deflate_add_bits(os,
length - deflate_length_slot_base[length_slot],
deflate_extra_length_bits[length_slot]);
if (!CAN_BUFFER(MAX_LITLEN_CODEWORD_LEN +
DEFLATE_MAX_EXTRA_LENGTH_BITS +
MAX_OFFSET_CODEWORD_LEN +
DEFLATE_MAX_EXTRA_OFFSET_BITS))
deflate_flush_bits(os);
/* Match offset */
offset_slot = c->p.n.offset_slot_full[offset];
deflate_add_bits(os,
codes->codewords.offset[offset_slot],
codes->lens.offset[offset_slot]);
if (!CAN_BUFFER(MAX_OFFSET_CODEWORD_LEN +
DEFLATE_MAX_EXTRA_OFFSET_BITS))
deflate_flush_bits(os);
deflate_add_bits(os,
offset - deflate_offset_slot_base[offset_slot],
deflate_extra_offset_bits[offset_slot]);
deflate_flush_bits(os);
/* Match */
deflate_write_match(os, length,
deflate_length_slot[length],
offset,
c->p.n.offset_slot_full[offset],
codes);
}
cur_node += length;
} while (cur_node != end_node);