Optimize Huffman code generation

[wimlib] / src / lzx-compress.c

diff --git a/src/lzx-compress.c b/src/lzx-compress.c
index 5246e1a1ed3b7add7f7c543c0a240177c3c1218e..edda90aefc1a59cc96bc37779b32df762a1b4521 100644 (file)
--- a/src/lzx-compress.c
+++ b/src/lzx-compress.c
@@ -179,9 +179,9 @@ typedef u32 block_cost_t;
 
 /* Codewords for the LZX main, length, and aligned offset Huffman codes  */
 struct lzx_codewords {
-       u16 main[LZX_MAINCODE_MAX_NUM_SYMBOLS];
-       u16 len[LZX_LENCODE_NUM_SYMBOLS];
-       u16 aligned[LZX_ALIGNEDCODE_NUM_SYMBOLS];
+       u32 main[LZX_MAINCODE_MAX_NUM_SYMBOLS];
+       u32 len[LZX_LENCODE_NUM_SYMBOLS];
+       u32 aligned[LZX_ALIGNEDCODE_NUM_SYMBOLS];
 };
 
 /* Codeword lengths (in bits) for the LZX main, length, and aligned offset
@@ -519,7 +519,7 @@ lzx_build_precode(const u8 lens[restrict],
                  input_idx_t precode_freqs[restrict LZX_PRECODE_NUM_SYMBOLS],
                  u8 output_syms[restrict num_syms],
                  u8 precode_lens[restrict LZX_PRECODE_NUM_SYMBOLS],
-                 u16 precode_codewords[restrict LZX_PRECODE_NUM_SYMBOLS],
+                 u32 precode_codewords[restrict LZX_PRECODE_NUM_SYMBOLS],
                  unsigned *num_additional_bits_ret)
 {
        memset(precode_freqs, 0,
@@ -688,7 +688,7 @@ lzx_write_compressed_code(struct output_bitstream *out,
        input_idx_t precode_freqs[LZX_PRECODE_NUM_SYMBOLS];
        u8 output_syms[num_syms];
        u8 precode_lens[LZX_PRECODE_NUM_SYMBOLS];
-       u16 precode_codewords[LZX_PRECODE_NUM_SYMBOLS];
+       u32 precode_codewords[LZX_PRECODE_NUM_SYMBOLS];
        unsigned i;
        unsigned num_output_syms;
        u8 precode_sym;
@@ -958,8 +958,8 @@ lzx_tally_match(unsigned match_len, unsigned match_offset,
        /* The match offset shall be encoded as a position slot (itself encoded
         * as part of the main symbol) and a position footer.  */
        position_slot = lzx_get_position_slot(match_offset, queue);
-       position_footer = (match_offset + LZX_OFFSET_OFFSET) -
-                               lzx_position_base[position_slot];
+       position_footer = (match_offset + LZX_OFFSET_OFFSET) &
+                               ((1U << lzx_get_num_extra_bits(position_slot)) - 1);
 
        /* The match length shall be encoded as a length header (itself encoded
         * as part of the main symbol) and an optional length footer.  */