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Optimize the LRGB->RGB conversion

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Turns out the rescaling expression can be expressed in form A*x+B
followed by bitshift for all 217 possible values of x. And while at
it, use templates to merge most of the locolor/hicolor conversion
functions.
This commit is contained in:
Ilari Liusvaara 2021-02-16 08:48:29 +02:00
parent 8d1889c116
commit b0809e58ed
1 changed files with 17 additions and 16 deletions
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33
src/library/framebuffer-pixfmt-lrgb.cpp
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@ -7,28 +7,29 @@ _pixfmt_lrgb::~_pixfmt_lrgb() throw()
{
}
template<typename T> static inline T convert_xcolor(uint32_t word, uint8_t rshift, uint8_t gshift,
uint8_t bshift, T A, T B)
{
const int sh = 6 * sizeof(T);
T l = A * ((word >> 15) & 0xF);
T r = (word >> 0) & 0x1F;
T g = (word >> 5) & 0x1F;
T b = (word >> 10) & 0x1F;
T x = (l*r+B) >> sh << rshift;
x += (l*g+B) >> sh << gshift;
x += (l*b+B) >> sh << bshift;
return x;
}
static inline uint32_t convert_lowcolor(uint32_t word, uint8_t rshift, uint8_t gshift, uint8_t bshift)
{
uint32_t l = ((word >> 15) & 0xF);
uint32_t r = l * ((word >> 0) & 0x1F);
uint32_t g = l * ((word >> 5) & 0x1F);
uint32_t b = l * ((word >> 10) & 0x1F);
uint32_t x = (((r << 8) - r + 232) / 465) << rshift;
x += (((g << 8) - g + 232) / 465) << gshift;
x += (((b << 8) - b + 232) / 465) << bshift;
return x;
return convert_xcolor<uint32_t>(word, rshift, gshift, bshift, 9200409, 8370567);
}
static inline uint64_t convert_hicolor(uint32_t word, uint8_t rshift, uint8_t gshift, uint8_t bshift)
{
uint64_t l = ((word >> 15) & 0xF);
uint64_t b = l * ((word >> 0) & 0x1F);
uint64_t g = l * ((word >> 5) & 0x1F);
uint64_t r = l * ((word >> 10) & 0x1F);
uint64_t x = (((r << 16) - r + 232) / 465) << rshift;
x += (((g << 16) - g + 232) / 465) << gshift;
x += (((b << 16) - b + 232) / 465) << bshift;
return x;
return convert_xcolor<uint64_t>(word, rshift, gshift, bshift, 39669812040285683ULL,
140434827090047ULL);
}
void _pixfmt_lrgb::decode(uint32_t* target, const uint8_t* src, size_t width)