X-Git-Url: https://wimlib.net/git/?a=blobdiff_plain;f=src%2Flzms-decompress.c;h=00e97d27e5c86de942c838c4a802bf72de61c3f0;hb=6c7b1783191ffe324953aad63735843feda9f901;hp=4d87e658fbc05e66983f9ba8c8a37834229afd27;hpb=dabaf1184dfd9581804da2a14fa3617ef61a3e06;p=wimlib diff --git a/src/lzms-decompress.c b/src/lzms-decompress.c index 4d87e658..00e97d27 100644 --- a/src/lzms-decompress.c +++ b/src/lzms-decompress.c @@ -1,7 +1,5 @@ /* * lzms-decompress.c - * - * A decompressor for the LZMS compression format. */ /* @@ -201,7 +199,6 @@ #include "wimlib/util.h" #include -#include #define LZMS_DECODE_TABLE_BITS 10 @@ -248,22 +245,6 @@ struct lzms_input_bitstream { size_t num_le16_remaining; }; -/* Probability entry for use by the range decoder when in a specific state. */ -struct lzms_probability_entry { - - /* Number of zeroes in the most recent LZMS_PROBABILITY_MAX bits that - * have been decoded using this probability entry. This is a cached - * value because it can be computed as LZMS_PROBABILITY_MAX minus the - * Hamming weight of the low-order LZMS_PROBABILITY_MAX bits of - * @recent_bits. */ - u32 num_recent_zero_bits; - - /* The most recent LZMS_PROBABILITY_MAX bits that have been decoded - * using this probability entry. The size of this variable, in bits, - * must be at least LZMS_PROBABILITY_MAX. */ - u64 recent_bits; -}; - /* Structure used for range decoding. This wraps around `struct * lzms_range_decoder_raw' to use and maintain probability entries. */ struct lzms_range_decoder { @@ -383,97 +364,10 @@ struct lzms_decompressor { u32 upcoming_delta_power; u32 upcoming_delta_offset; - /* Used for postprocessing */ + /* Used for postprocessing. */ s32 last_target_usages[65536]; }; -/* A table that maps position slots to their base values. These are constants - * computed at runtime by lzms_compute_slot_bases(). */ -static u32 lzms_position_slot_base[LZMS_MAX_NUM_OFFSET_SYMS + 1]; - -/* A table that maps length slots to their base values. These are constants - * computed at runtime by lzms_compute_slot_bases(). */ -static u32 lzms_length_slot_base[LZMS_NUM_LEN_SYMS + 1]; - -static void -lzms_decode_delta_rle_slot_bases(u32 slot_bases[], - const u8 delta_run_lens[], size_t num_run_lens) -{ - u32 delta = 1; - u32 base = 0; - size_t slot = 0; - for (size_t i = 0; i < num_run_lens; i++) { - u8 run_len = delta_run_lens[i]; - while (run_len--) { - base += delta; - slot_bases[slot++] = base; - } - delta <<= 1; - } -} - -/* Initialize the global position and length slot tables. */ -static void -lzms_compute_slot_bases(void) -{ - /* If an explicit formula that maps LZMS position and length slots to - * slot bases exists, then it could be used here. But until one is - * found, the following code fills in the slots using the observation - * that the increase from one slot base to the next is an increasing - * power of 2. Therefore, run-length encoding of the delta of adjacent - * entries can be used. */ - static const u8 position_slot_delta_run_lens[] = { - 9, 0, 9, 7, 10, 15, 15, 20, - 20, 30, 33, 40, 42, 45, 60, 73, - 80, 85, 95, 105, 6, - }; - - static const u8 length_slot_delta_run_lens[] = { - 27, 4, 6, 4, 5, 2, 1, 1, - 1, 1, 1, 0, 0, 0, 0, 0, - 1, - }; - - lzms_decode_delta_rle_slot_bases(lzms_position_slot_base, - position_slot_delta_run_lens, - ARRAY_LEN(position_slot_delta_run_lens)); - - lzms_position_slot_base[LZMS_MAX_NUM_OFFSET_SYMS] = 0x7fffffff; - - lzms_decode_delta_rle_slot_bases(lzms_length_slot_base, - length_slot_delta_run_lens, - ARRAY_LEN(length_slot_delta_run_lens)); - - lzms_length_slot_base[LZMS_NUM_LEN_SYMS] = 0x400108ab; -} - -/* Initialize the global position length slot tables if not done so already. */ -static void -lzms_init_slot_bases(void) -{ - static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER; - static bool already_computed = false; - - if (unlikely(!already_computed)) { - pthread_mutex_lock(&mutex); - if (!already_computed) { - lzms_compute_slot_bases(); - already_computed = true; - } - pthread_mutex_unlock(&mutex); - } -} - -/* Return the position slot for the specified offset. */ -static u32 -lzms_get_position_slot_raw(u32 offset) -{ - u32 position_slot = 0; - while (lzms_position_slot_base[position_slot + 1] <= offset) - position_slot++; - return position_slot; -} - /* Initialize the input bitstream @is to read forwards from the specified * compressed data buffer @in that is @in_limit 16-bit integers long. */ static void @@ -684,7 +578,7 @@ lzms_rebuild_adaptive_huffman_code(struct lzms_huffman_decoder *dec) /* Decode and return the next Huffman-encoded symbol from the LZMS-compressed * block using the specified Huffman decoder. */ static u32 -lzms_decode_huffman_symbol(struct lzms_huffman_decoder *dec) +lzms_huffman_decode_symbol(struct lzms_huffman_decoder *dec) { const u8 *lens = dec->lens; const u16 *decode_table = dec->decode_table; @@ -749,7 +643,7 @@ lzms_decode_value(struct lzms_huffman_decoder *dec) /* Read the slot (position slot, length slot, etc.), which is encoded as * a Huffman symbol. */ - slot = lzms_decode_huffman_symbol(dec); + slot = lzms_huffman_decode_symbol(dec); LZMS_ASSERT(dec->slot_base_tab != NULL); @@ -884,7 +778,7 @@ lzms_decode_delta_match(struct lzms_decompressor *ctx) bit = lzms_range_decode_bit(&ctx->delta_match_range_decoder); if (bit == 0) { - power = lzms_decode_huffman_symbol(&ctx->delta_power_decoder); + power = lzms_huffman_decode_symbol(&ctx->delta_power_decoder); raw_offset = lzms_decode_value(&ctx->delta_offset_decoder); } else { int i; @@ -927,7 +821,7 @@ lzms_decode_match(struct lzms_decompressor *ctx) static int lzms_decode_literal(struct lzms_decompressor *ctx) { - u8 literal = lzms_decode_huffman_symbol(&ctx->literal_decoder); + u8 literal = lzms_huffman_decode_symbol(&ctx->literal_decoder); LZMS_DEBUG("Decoded literal: 0x%02x", literal); return lzms_copy_literal(ctx, literal); } @@ -1027,7 +921,7 @@ lzms_init_decompressor(struct lzms_decompressor *ctx, /* Calculate the number of position slots needed for this compressed * block. */ - num_position_slots = lzms_get_position_slot_raw(ulen - 1) + 1; + num_position_slots = lzms_get_position_slot(ulen - 1) + 1; LZMS_DEBUG("Using %u position slots", num_position_slots); @@ -1145,7 +1039,8 @@ lzms_decompress(const void *compressed_data, size_t compressed_size, * searched for a position of INT32_MAX or greater. */ if (uncompressed_size >= INT32_MAX) { LZMS_DEBUG("Uncompressed length too large " - "(got %u, expected < INT32_MAX)", ulen); + "(got %zu, expected < INT32_MAX)", + uncompressed_size); return -1; }