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Specialize (D)BITMAP:sample_texture when s is power of two

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This commit is contained in:
Ilari Liusvaara 2017-07-13 20:27:38 +03:00
parent f85cdab6c5
commit 298610752b
1 changed files with 57 additions and 1 deletions
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58
src/lua/gui-bitmap.cpp
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@ -536,11 +536,67 @@ namespace
}
}
//Similar as _sample_texture(), but for the s=2^n, n integer special case.
template<typename pixel>
inline void _sample_texture_log2(pixel* dest, uint32_t dwidth, uint32_t dheight, pixel* source,
uint32_t swidth, uint32_t sheight, int32_t xx, int32_t xy, int32_t x0, int32_t yx, int32_t yy,
int32_t y0, int32_t log2s, bool wrap, pixel transparent)
{
uint32_t th = (1 << log2s) >> 1; //Two shifts, as log2s=0 should give th=0.
uint32_t fsmask = (1u << log2s) - 1;
uint64_t bias = 1ull << (31 + log2s);
size_t didx = 0;
for(int32_t i = 0; i < (int32_t)dheight; i++) {
uint64_t ssx = (int64_t)xy * i + (int64_t)x0 + bias;
uint64_t ssy = (int64_t)yy * i + (int64_t)y0 + bias;
for(int32_t j = 0; j < (int32_t)dwidth; j++) {
//Compute whole and fractional parts.
uint32_t _isx = ssx >> log2s;
uint32_t fsx = ssx & fsmask;
uint32_t _isy = ssy >> log2s;
uint32_t fsy = ssy & fsmask;
//The above always give positive fractional parts.
//Round the whole parts.
_isx += fsx > th;
_isy += fsy > th;
//Remove biases.
int32_t isx = _isx - (1u << 31);
int32_t isy = _isy - (1u << 31);
//Compute color.
pixel p = transparent;
if(wrap) {
isx = isx % swidth;
if(isx < 0) isx += swidth;
isy = isy % sheight;
if(isy < 0) isy += sheight;
p = source[isy * swidth + isx];
} else if(isx >= 0 && isx < (int32_t)swidth && isy >= 0 && isy < (int32_t)sheight) {
p = source[isy * swidth + isx];
}
dest[didx] = p;
//Update values for next pixel.
ssx += (int64_t)xx;
ssy += (int64_t)yx;
didx++;
}
}
}
template<typename pixel>
inline void _sample_texture(pixel* dest, uint32_t dwidth, uint32_t dheight, pixel* source, uint32_t swidth,
uint32_t sheight, int32_t xx, int32_t xy, int32_t x0, int32_t yx, int32_t yy, int32_t y0, uint32_t s,
bool wrap, pixel transparent)
{
if((s & (s - 1)) == 0) {
//S is power of two. Compute the logarithm.
uint32_t log2s = 0;
while(s > 1) {
log2s++;
s >>= 1;
}
return _sample_texture_log2(dest, dwidth, dheight, source, swidth, sheight, xx, xy, x0, yx,
yy, y0, log2s, wrap, transparent);
}
int32_t th = s / 2;
size_t didx = 0;
for(int32_t i = 0; i < (int32_t)dheight; i++) {
@ -566,7 +622,7 @@ namespace
isy = isy % sheight;
if(isy < 0) isy += sheight;
p = source[isy * swidth + isx];
} else if(isx >= 0 && isx < swidth && isy >= 0 && isy < sheight) {
} else if(isx >= 0 && isx < (int32_t)swidth && isy >= 0 && isy < (int32_t)sheight) {
p = source[isy * swidth + isx];
}
dest[didx] = p;