diff options
Diffstat (limited to 'doc/educational_decoder/zstd_decompress.c')
| -rw-r--r-- | doc/educational_decoder/zstd_decompress.c | 27 |
1 files changed, 15 insertions, 12 deletions
diff --git a/doc/educational_decoder/zstd_decompress.c b/doc/educational_decoder/zstd_decompress.c index 9ade7650..839e085b 100644 --- a/doc/educational_decoder/zstd_decompress.c +++ b/doc/educational_decoder/zstd_decompress.c @@ -997,7 +997,8 @@ static void decompress_sequences(frame_context_t *const ctx, const size_t num_sequences); static sequence_command_t decode_sequence(sequence_states_t *const state, const u8 *const src, - i64 *const offset); + i64 *const offset, + int lastSequence); static void decode_seq_table(FSE_dtable *const table, istream_t *const in, const seq_part_t type, const seq_mode_t mode); @@ -1017,12 +1018,7 @@ static size_t decode_sequences(frame_context_t *const ctx, istream_t *in, // This is a variable size field using between 1 and 3 bytes. Let's call its // first byte byte0." u8 header = IO_read_bits(in, 8); - if (header == 0) { - // "There are no sequences. The sequence section stops there. - // Regenerated content is defined entirely by literals section." - *sequences = NULL; - return 0; - } else if (header < 128) { + if (header < 128) { // "Number_of_Sequences = byte0 . Uses 1 byte." num_sequences = header; } else if (header < 255) { @@ -1033,6 +1029,12 @@ static size_t decode_sequences(frame_context_t *const ctx, istream_t *in, num_sequences = IO_read_bits(in, 16) + 0x7F00; } + if (num_sequences == 0) { + // "There are no sequences. The sequence section stops there." + *sequences = NULL; + return 0; + } + *sequences = malloc(num_sequences * sizeof(sequence_command_t)); if (!*sequences) { BAD_ALLOC(); @@ -1114,7 +1116,7 @@ static void decompress_sequences(frame_context_t *const ctx, istream_t *in, for (size_t i = 0; i < num_sequences; i++) { // Decode sequences one by one - sequences[i] = decode_sequence(&states, src, &bit_offset); + sequences[i] = decode_sequence(&states, src, &bit_offset, i==num_sequences-1); } if (bit_offset != 0) { @@ -1125,7 +1127,8 @@ static void decompress_sequences(frame_context_t *const ctx, istream_t *in, // Decode a single sequence and update the state static sequence_command_t decode_sequence(sequence_states_t *const states, const u8 *const src, - i64 *const offset) { + i64 *const offset, + int lastSequence) { // "Each symbol is a code in its own context, which specifies Baseline and // Number_of_Bits to add. Codes are FSE compressed, and interleaved with raw // additional bits in the same bitstream." @@ -1160,7 +1163,7 @@ static sequence_command_t decode_sequence(sequence_states_t *const states, // Literals_Length_State is updated, followed by Match_Length_State, and // then Offset_State." // If the stream is complete don't read bits to update state - if (*offset != 0) { + if (!lastSequence) { FSE_update_state(&states->ll_table, &states->ll_state, src, offset); FSE_update_state(&states->ml_table, &states->ml_state, src, offset); FSE_update_state(&states->of_table, &states->of_state, src, offset); @@ -1210,7 +1213,7 @@ static void decode_seq_table(FSE_dtable *const table, istream_t *const in, break; } case seq_repeat: - // "Repeat_Mode : re-use distribution table from previous compressed + // "Repeat_Mode : reuse distribution table from previous compressed // block." // Nothing to do here, table will be unchanged if (!table->symbols) { @@ -1399,7 +1402,7 @@ size_t ZSTD_get_decompressed_size(const void *src, const size_t src_len) { /******* END OUTPUT SIZE COUNTING *********************************************/ /******* DICTIONARY PARSING ***************************************************/ -dictionary_t* create_dictionary() { +dictionary_t* create_dictionary(void) { dictionary_t* const dict = calloc(1, sizeof(dictionary_t)); if (!dict) { BAD_ALLOC(); |