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/* The base dither matrix we use to derive optimized ones for 565 and 4444
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{ 0, 32, 8, 40, 2, 34, 10, 42 },
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{ 48, 16, 56, 24, 50, 18, 58, 26 },
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{ 12, 44, 4, 36, 14, 46, 6, 38 },
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{ 60, 28, 52, 20, 62, 30, 54, 22 },
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{ 3, 35, 11, 43, 1, 33, 9, 41 },
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{ 51, 19, 59, 27, 49, 17, 57, 25 },
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{ 15, 47, 7, 39, 13, 45, 5, 37 },
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{ 63, 31, 55, 23, 61, 29, 53, 21 }
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The 4444 version only needs 4 bits, and given that we can reduce its size
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since the other 4x4 sub pieces all look the same once we truncate the bits.
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The 565 version only needs 3 bits for red/blue, and only 2 bits for green.
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For simplicity, we store 3 bits, and have the dither macros for green know
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this, and they shift the dither value down by 1 to make it 2 bits.
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#ifdef ENABLE_DITHER_MATRIX_4X4
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const uint8_t gDitherMatrix_4Bit_4X4[4][4] = {
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const uint8_t gDitherMatrix_3Bit_4X4[4][4] = {
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#else // used packed shorts for a scanlines worth of dither values
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const uint16_t gDitherMatrix_4Bit_16[4] = {
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0xA280, 0x6E4C, 0x91B3, 0x5D7F
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const uint16_t gDitherMatrix_3Bit_16[4] = {
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0x5140, 0x3726, 0x4051, 0x2637