fergalmoran/ladybird
1
0
Fork 0
mirror of https://github.com/fergalmoran/ladybird.git synced 2026-01-06 16:45:03 +00:00
Code Issues Packages Projects Releases Wiki Activity

LibGfx/WebPWriter: Put hot loop in its own function

Browse Source 
This makes it easier to compare the generated assembly for this function
in different scenarios.

No behavior or perf change.
This commit is contained in:
Nico Weber
2024-05-08 08:22:23 -04:00
committed by Tim Flynn
parent ed2658d72c
commit 1bd1b6e5e9
1 changed files with 23 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files

39
Userland/Libraries/LibGfx/ImageFormats/WebPWriterLossless.cpp
View File

@@ -25,6 +25,28 @@ static bool are_all_pixels_opaque(Bitmap const& bitmap)
return true;
}
NEVER_INLINE static ErrorOr<void> write_image_data(LittleEndianOutputBitStream& bit_stream, Bitmap const& bitmap, bool all_pixels_are_opaque)
{
// This is currently the hot loop. Keep performance in mind when you change it.
for (ARGB32 pixel : bitmap) {
u8 a = pixel >> 24;
u8 r = pixel >> 16;
u8 g = pixel >> 8;
u8 b = pixel;
// We wrote a huffman table that gives every symbol 8 bits. That means we can write the image data
// out uncompressed –- but we do need to reverse the bit order of the bytes.
TRY(bit_stream.write_bits(Compress::reverse8_lookup_table[g], 8u));
TRY(bit_stream.write_bits(Compress::reverse8_lookup_table[r], 8u));
TRY(bit_stream.write_bits(Compress::reverse8_lookup_table[b], 8u));
// If all pixels are opaque, we wrote a one-element huffman table for alpha, which needs 0 bits per element.
if (!all_pixels_are_opaque)
TRY(bit_stream.write_bits(Compress::reverse8_lookup_table[a], 8u));
}
return {};
}
static ErrorOr<void> write_VP8L_image_data(Stream& stream, Bitmap const& bitmap)
{
LittleEndianOutputBitStream bit_stream { MaybeOwned<Stream>(stream) };
@@ -116,22 +138,7 @@ static ErrorOr<void> write_VP8L_image_data(Stream& stream, Bitmap const& bitmap)
TRY(bit_stream.write_bits(0u, 1u)); // symbol0
// Image data.
for (ARGB32 pixel : bitmap) {
u8 a = pixel >> 24;
u8 r = pixel >> 16;
u8 g = pixel >> 8;
u8 b = pixel;
// We wrote a huffman table that gives every symbol 8 bits. That means we can write the image data
// out uncompressed –- but we do need to reverse the bit order of the bytes.
TRY(bit_stream.write_bits(Compress::reverse8_lookup_table[g], 8u));
TRY(bit_stream.write_bits(Compress::reverse8_lookup_table[r], 8u));
TRY(bit_stream.write_bits(Compress::reverse8_lookup_table[b], 8u));
// If all pixels are opaque, we wrote a one-element huffman table for alpha, which needs 0 bits per element.
if (!all_pixels_are_opaque)
TRY(bit_stream.write_bits(Compress::reverse8_lookup_table[a], 8u));
}
TRY(write_image_data(bit_stream, bitmap, all_pixels_are_opaque));
// FIXME: Make ~LittleEndianOutputBitStream do this, or make it VERIFY() that it has happened at least.
TRY(bit_stream.align_to_byte_boundary());