diff options
Diffstat (limited to '')
| -rw-r--r-- | src/liblzma/rangecoder/price_table_init.c | 33 |
1 files changed, 20 insertions, 13 deletions
diff --git a/src/liblzma/rangecoder/price_table_init.c b/src/liblzma/rangecoder/price_table_init.c index 4714dfd6..9c7d799b 100644 --- a/src/liblzma/rangecoder/price_table_init.c +++ b/src/liblzma/rangecoder/price_table_init.c @@ -23,25 +23,32 @@ #endif -#define NUM_BITS (BIT_MODEL_TOTAL_BITS - MOVE_REDUCING_BITS) - - -uint32_t lzma_rc_prob_prices[BIT_MODEL_TOTAL >> MOVE_REDUCING_BITS]; +uint32_t lzma_rc_prices[RC_PRICE_TABLE_SIZE]; extern void lzma_rc_init(void) { - // Initialize lzma_rc_prob_prices[]. - for (int i = NUM_BITS - 1; i >= 0; --i) { - const uint32_t start = 1 << (NUM_BITS - i - 1); - const uint32_t end = 1 << (NUM_BITS - i); - - for (uint32_t j = start; j < end; ++j) { - lzma_rc_prob_prices[j] = (i << BIT_PRICE_SHIFT_BITS) - + (((end - j) << BIT_PRICE_SHIFT_BITS) - >> (NUM_BITS - i - 1)); + for (uint32_t i = (UINT32_C(1) << RC_MOVE_REDUCING_BITS) / 2; + i < RC_BIT_MODEL_TOTAL; + i += (UINT32_C(1) << RC_MOVE_REDUCING_BITS)) { + const uint32_t cycles_bits = RC_BIT_PRICE_SHIFT_BITS; + uint32_t w = i; + uint32_t bit_count = 0; + + for (uint32_t j = 0; j < cycles_bits; ++j) { + w *= w; + bit_count <<= 1; + + while (w >= (UINT32_C(1) << 16)) { + w >>= 1; + ++bit_count; + } } + + lzma_rc_prices[i >> RC_MOVE_REDUCING_BITS] + = (RC_BIT_MODEL_TOTAL_BITS << cycles_bits) + - 15 - bit_count; } return; |