lzx-compress.c: Use pointers in lzx_optimize_block()

[wimlib] / src / lzx-compress.c

diff --git a/src/lzx-compress.c b/src/lzx-compress.c
index 5246e1a1ed3b7add7f7c543c0a240177c3c1218e..26a0c0cbbfb5c38c7f29d3828b4434276418af7b 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.  */
@@ -1322,7 +1322,12 @@ lzx_optimize_block(struct lzx_compressor *ctx, struct lzx_block_spec *spec,
                spec->num_chosen_matches = 0;
                memset(&freqs, 0, sizeof(freqs));
 
-               for (unsigned i = spec->window_pos; i < spec->window_pos + spec->block_size; ) {
+               const u8 *window_ptr = &ctx->window[spec->window_pos];
+               const u8 *window_end = &window_ptr[spec->block_size];
+               struct lzx_match *next_chosen_match =
+                       &ctx->chosen_matches[spec->chosen_matches_start_pos];
+
+               while (window_ptr != window_end) {
                        struct raw_match raw_match;
                        struct lzx_match lzx_match;
 
@@ -1350,29 +1355,25 @@ lzx_optimize_block(struct lzx_compressor *ctx, struct lzx_block_spec *spec,
                                         * null value and therefore cannot
                                         * generate such matches.  */
                                        BUILD_BUG_ON(LZX_MIN_MATCH_LEN != 2);
-                                       lzx_match.data = lzx_tally_literal(ctx->window[i],
+                                       lzx_match.data = lzx_tally_literal(*window_ptr++,
                                                                           &freqs);
-                                       i += 1;
-                                       ctx->chosen_matches[spec->chosen_matches_start_pos +
-                                                           spec->num_chosen_matches++]
-                                                           = lzx_match;
-                                       lzx_match.data = lzx_tally_literal(ctx->window[i],
+                                       *next_chosen_match++ = lzx_match;
+                                       lzx_match.data = lzx_tally_literal(*window_ptr++,
                                                                           &freqs);
-                                       i += 1;
                                } else {
                                        lzx_match.data = lzx_tally_match(raw_match.len,
                                                                         raw_match.offset,
                                                                         &freqs,
                                                                         &ctx->queue);
-                                       i += raw_match.len;
+                                       window_ptr += raw_match.len;
                                }
                        } else {
-                               lzx_match.data = lzx_tally_literal(ctx->window[i], &freqs);
-                               i += 1;
+                               lzx_match.data = lzx_tally_literal(*window_ptr++, &freqs);
                        }
-                       ctx->chosen_matches[spec->chosen_matches_start_pos +
-                                           spec->num_chosen_matches++] = lzx_match;
+                       *next_chosen_match++ = lzx_match;
                }
+               spec->num_chosen_matches = next_chosen_match -
+                                          &ctx->chosen_matches[spec->chosen_matches_start_pos];
 
                lzx_make_huffman_codes(&freqs, &spec->codes,
                                       ctx->num_main_syms);