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Refactor UnpackBppTile and PackBppTile functions for clarity and correctness

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- Initialized the snes_tile8 structure to zero in UnpackBppTile for safety.
- Reordered loops in UnpackBppTile to process rows before columns, improving readability.
- Corrected bit manipulation logic in both UnpackBppTile and PackBppTile to ensure accurate color value handling.
- Enhanced test cases for 2bpp and 4bpp tile unpacking to validate expected results, improving test coverage.
This commit is contained in:
scawful
2025-09-25 11:16:13 -04:00
parent 255a757304
commit 4c6342cb73
2 changed files with 84 additions and 58 deletions
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64
test/gfx/snes_tile_test.cc
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@@ -22,29 +22,55 @@ TEST(SnesTileTest, UnpackBppTile) {
EXPECT_EQ(tile1bpp.data[63], 1); // Last pixel
// Test 2bpp tile unpacking
std::vector<uint8_t> data2bpp = {0x80, 0x40, 0x20, 0x10, 0x08, 0x04,
0x02, 0x01, 0x01, 0x02, 0x04, 0x08,
0x10, 0x20, 0x40, 0x80};
// Create test data where we know the expected results
// For 2bpp: 16 bytes total (8 rows × 2 bytes per row)
// Each row has 2 bytes: plane 0 byte, plane 1 byte
// First pixel should be 3 (both bits set): plane0 bit7=1, plane1 bit7=1
// Last pixel of first row should be 1: plane0 bit0=1, plane1 bit0=0
std::vector<uint8_t> data2bpp = {
0x81, 0x80, // Row 0: plane0=10000001, plane1=10000000
0x00, 0x00, // Row 1: plane0=00000000, plane1=00000000
0x00, 0x00, // Row 2: plane0=00000000, plane1=00000000
0x00, 0x00, // Row 3: plane0=00000000, plane1=00000000
0x00, 0x00, // Row 4: plane0=00000000, plane1=00000000
0x00, 0x00, // Row 5: plane0=00000000, plane1=00000000
0x00, 0x00, // Row 6: plane0=00000000, plane1=00000000
0x01, 0x81 // Row 7: plane0=00000001, plane1=10000001
};
auto tile2bpp = gfx::UnpackBppTile(data2bpp, 0, 2);
EXPECT_EQ(tile2bpp.data[0], 3); // First pixel (both bits set)
EXPECT_EQ(tile2bpp.data[7],
1); // Last pixel of first row (only first bit set)
EXPECT_EQ(tile2bpp.data[56],
2); // First pixel of last row (only second bit set)
EXPECT_EQ(tile2bpp.data[63], 3); // Last pixel (both bits set)
EXPECT_EQ(tile2bpp.data[0], 3); // First pixel: 1|1<<1 = 3
EXPECT_EQ(tile2bpp.data[7], 1); // Last pixel of first row: 1|0<<1 = 1
EXPECT_EQ(tile2bpp.data[56], 2); // First pixel of last row: 0|1<<1 = 2
EXPECT_EQ(tile2bpp.data[63], 3); // Last pixel: 1|1<<1 = 3
// Test 4bpp tile unpacking
// Test 4bpp tile unpacking
// According to SnesLab: First planes 1&2 intertwined, then planes 3&4 intertwined
// 32 bytes total: 16 bytes for planes 1&2, then 16 bytes for planes 3&4
std::vector<uint8_t> data4bpp = {
0x80, 0x40, 0x20, 0x10, 0x08, 0x04, 0x02, 0x01, 0x01, 0x02, 0x04,
0x08, 0x10, 0x20, 0x40, 0x80, 0x80, 0x40, 0x20, 0x10, 0x08, 0x04,
0x02, 0x01, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80};
// Planes 1&2 intertwined (rows 0-7)
0x81, 0x80, // Row 0: bp1=10000001, bp2=10000000
0x00, 0x00, // Row 1: bp1=00000000, bp2=00000000
0x00, 0x00, // Row 2: bp1=00000000, bp2=00000000
0x00, 0x00, // Row 3: bp1=00000000, bp2=00000000
0x00, 0x00, // Row 4: bp1=00000000, bp2=00000000
0x00, 0x00, // Row 5: bp1=00000000, bp2=00000000
0x00, 0x00, // Row 6: bp1=00000000, bp2=00000000
0x01, 0x81, // Row 7: bp1=00000001, bp2=10000001
// Planes 3&4 intertwined (rows 0-7)
0x81, 0x80, // Row 0: bp3=10000001, bp4=10000000
0x00, 0x00, // Row 1: bp3=00000000, bp4=00000000
0x00, 0x00, // Row 2: bp3=00000000, bp4=00000000
0x00, 0x00, // Row 3: bp3=00000000, bp4=00000000
0x00, 0x00, // Row 4: bp3=00000000, bp4=00000000
0x00, 0x00, // Row 5: bp3=00000000, bp4=00000000
0x00, 0x00, // Row 6: bp3=00000000, bp4=00000000
0x01, 0x81 // Row 7: bp3=00000001, bp4=10000001
};
auto tile4bpp = gfx::UnpackBppTile(data4bpp, 0, 4);
EXPECT_EQ(tile4bpp.data[0], 0xF); // First pixel (all bits set)
EXPECT_EQ(tile4bpp.data[7],
0x5); // Last pixel of first row (bits 0 and 2 set)
EXPECT_EQ(tile4bpp.data[56],
0xA); // First pixel of last row (bits 1 and 3 set)
EXPECT_EQ(tile4bpp.data[63], 0xF); // Last pixel (all bits set)
EXPECT_EQ(tile4bpp.data[0], 0xF); // First pixel: 1|1<<1|1<<2|1<<3 = 15
EXPECT_EQ(tile4bpp.data[7], 0x5); // Last pixel of first row: 1|0<<1|1<<2|0<<3 = 5
EXPECT_EQ(tile4bpp.data[56], 0xA); // First pixel of last row: 0|1<<1|0<<2|1<<3 = 10
EXPECT_EQ(tile4bpp.data[63], 0xF); // Last pixel: 1|1<<1|1<<2|1<<3 = 15
}
TEST(SnesTileTest, PackBppTile) {