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LibVideo: Cache 64 bits at a time for reading in BitStream

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Reads will now be done in larger chunks at a time.

The public read_byte() function was removed in favor of a private
fill_reservoir() function which will be used to fill the 64-bit
reservoir field which will then be bit-shifted and masked as necessary
for subsequent arbitrary bit-sized reads.

read_f(n) was renamed to read_bits to be clearer about its use.
This commit is contained in:
Zaggy1024 2022-10-08 19:55:24 -05:00 • committed by Andrew Kaster
parent b37ea6b414
commit 7f46033c01
3 changed files with 69 additions and 60 deletions
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22
Userland/Libraries/LibVideo/VP9/Parser.cpp
View file

@ -95,7 +95,7 @@ ErrorOr<void> Parser::refresh_probs()
/* (6.2) */
ErrorOr<void> Parser::uncompressed_header()
{
auto frame_marker = TRY(m_bit_stream->read_f(2));
auto frame_marker = TRY(m_bit_stream->read_bits(2));
if (frame_marker != 2)
return Error::from_string_literal("uncompressed_header: Frame marker must be 2");
auto profile_low_bit = TRY(m_bit_stream->read_bit());
@ -105,7 +105,7 @@ ErrorOr<void> Parser::uncompressed_header()
return Error::from_string_literal("uncompressed_header: Profile 3 reserved bit was non-zero");
auto show_existing_frame = TRY(m_bit_stream->read_bit());
if (show_existing_frame) {
m_frame_to_show_map_index = TRY(m_bit_stream->read_f(3));
m_frame_to_show_map_index = TRY(m_bit_stream->read_bits(3));
m_header_size_in_bytes = 0;
m_refresh_frame_flags = 0;
m_loop_filter_level = 0;
@ -128,7 +128,7 @@ ErrorOr<void> Parser::uncompressed_header()
m_frame_is_intra = !m_show_frame && TRY(m_bit_stream->read_bit());
if (!m_error_resilient_mode) {
m_reset_frame_context = TRY(m_bit_stream->read_f(2));
m_reset_frame_context = TRY(m_bit_stream->read_bits(2));
} else {
m_reset_frame_context = 0;
}
@ -150,7 +150,7 @@ ErrorOr<void> Parser::uncompressed_header()
} else {
m_refresh_frame_flags = TRY(m_bit_stream->read_f8());
for (auto i = 0; i < 3; i++) {
m_ref_frame_idx[i] = TRY(m_bit_stream->read_f(3));
m_ref_frame_idx[i] = TRY(m_bit_stream->read_bits(3));
m_ref_frame_sign_bias[LastFrame + i] = TRY(m_bit_stream->read_bit());
}
TRY(frame_size_with_refs());
@ -167,7 +167,7 @@ ErrorOr<void> Parser::uncompressed_header()
m_frame_parallel_decoding_mode = true;
}
m_frame_context_idx = TRY(m_bit_stream->read_f(2));
m_frame_context_idx = TRY(m_bit_stream->read_bits(2));
if (m_frame_is_intra || m_error_resilient_mode) {
setup_past_independence();
if (m_frame_type == KeyFrame || m_error_resilient_mode || m_reset_frame_context == 3) {
@ -209,7 +209,7 @@ ErrorOr<void> Parser::color_config()
m_bit_depth = 8;
}
auto color_space = TRY(m_bit_stream->read_f(3));
auto color_space = TRY(m_bit_stream->read_bits(3));
VERIFY(color_space <= RGB);
m_color_space = static_cast<ColorSpace>(color_space);
@ -291,15 +291,15 @@ ErrorOr<void> Parser::read_interpolation_filter()
if (TRY(m_bit_stream->read_bit())) {
m_interpolation_filter = Switchable;
} else {
m_interpolation_filter = literal_to_type[TRY(m_bit_stream->read_f(2))];
m_interpolation_filter = literal_to_type[TRY(m_bit_stream->read_bits(2))];
}
return {};
}
ErrorOr<void> Parser::loop_filter_params()
{
m_loop_filter_level = TRY(m_bit_stream->read_f(6));
m_loop_filter_sharpness = TRY(m_bit_stream->read_f(3));
m_loop_filter_level = TRY(m_bit_stream->read_bits(6));
m_loop_filter_sharpness = TRY(m_bit_stream->read_bits(3));
m_loop_filter_delta_enabled = TRY(m_bit_stream->read_bit());
if (m_loop_filter_delta_enabled) {
if (TRY(m_bit_stream->read_bit())) {
@ -362,7 +362,7 @@ ErrorOr<void> Parser::segmentation_params()
m_feature_enabled[i][j] = feature_enabled;
if (feature_enabled) {
auto bits_to_read = segmentation_feature_bits[j];
feature_value = TRY(m_bit_stream->read_f(bits_to_read));
feature_value = TRY(m_bit_stream->read_bits(bits_to_read));
if (segmentation_feature_signed[j]) {
if (TRY(m_bit_stream->read_bit()))
feature_value = -feature_value;
@ -764,7 +764,7 @@ ErrorOr<void> Parser::decode_tiles()
if (last_tile)
tile_size = m_bit_stream->bytes_remaining();
else
tile_size = TRY(m_bit_stream->read_f(32));
tile_size = TRY(m_bit_stream->read_bits(32));
m_mi_row_start = get_tile_offset(tile_row, m_mi_rows, m_tile_rows_log2);
m_mi_row_end = get_tile_offset(tile_row + 1, m_mi_rows, m_tile_rows_log2);