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feat(ricepp): another 15% decode speedup

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This commit is contained in:
Marcus Holland-Moritz 2024-02-04 13:48:23 +01:00
parent 107a89425e
commit 4811199406
1 changed files with 9 additions and 0 deletions
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9
ricepp/include/ricepp/bitstream_reader.h
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@ -65,6 +65,10 @@ class bitstream_reader final {
size_t find_first_set() { size_t find_first_set() {
size_t zeros = 0; size_t zeros = 0;
if (bit_pos_ != 0) [[likely]] { if (bit_pos_ != 0) [[likely]] {
if (peek_bit()) [[likely]] {
skip_bits(1);
return zeros;
}
size_t const remaining_bits = kBitsTypeBits - bit_pos_; size_t const remaining_bits = kBitsTypeBits - bit_pos_;
bits_type const bits = peek_bits(remaining_bits); bits_type const bits = peek_bits(remaining_bits);
size_t const ffs = std::countr_zero(bits); size_t const ffs = std::countr_zero(bits);
@ -107,6 +111,11 @@ class bitstream_reader final {
} }
} }
bool peek_bit() {
assert(bit_pos_ > 0 && bit_pos_ < kBitsTypeBits);
return (data_ & (static_cast<bits_type>(1) << bit_pos_)) != 0;
}
bits_type peek_bits(size_t num_bits) { bits_type peek_bits(size_t num_bits) {
assert(bit_pos_ + num_bits <= kBitsTypeBits); assert(bit_pos_ + num_bits <= kBitsTypeBits);
if (bit_pos_ == 0) [[unlikely]] { if (bit_pos_ == 0) [[unlikely]] {