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Small optimization: replace division with multiply.

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This commit is contained in:
homm 2014-10-18 04:00:07 +04:00
parent 0ff4b53a72
commit 7d77db20ad
1 changed files with 49 additions and 33 deletions
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82
libImaging/BoxBlur.c
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@ -12,22 +12,21 @@ HorizontalBoxBlur32(Imaging im, Imaging imOut, float floatRadius)
ImagingSectionCookie cookie;
int x, y, pix;
unsigned int acc[4];
unsigned int bulk[4];
UINT32 acc[4];
UINT32 bulk[4];
typedef UINT8 pixel[4];
pixel *line;
int lastx = im->xsize - 1;
int radius = (int) floatRadius;
UINT8 rem = (UINT8) (256 * (floatRadius - radius));
int w = 256 * (radius * 2 + 1) + rem * 2;
int w2 = w / 2;
UINT32 ww = (UINT32) (1 << 24) / (floatRadius * 2 + 1);
UINT32 fw = ((1 << 24) - (radius * 2 + 1) * ww) / 2;
int edgeA = MIN(radius + 1, im->xsize);
int edgeB = MAX(im->xsize - radius - 1, 0);
// printf("%d %d %d\n", rem, w, w2);
// printf(">>> %d %d %d\n", radius, ww, fw);
#define MOVE_ACC(acc, substract, add) \
acc[0] += line[add][0] - line[substract][0]; \
@ -36,14 +35,14 @@ HorizontalBoxBlur32(Imaging im, Imaging imOut, float floatRadius)
acc[3] += line[add][3] - line[substract][3];
#define ADD_FAR(bulk, acc, left, right) \
bulk[0] = (acc[0] << 8) + (line[left][0] + line[right][0]) * rem; \
bulk[1] = (acc[1] << 8) + (line[left][1] + line[right][1]) * rem; \
bulk[2] = (acc[2] << 8) + (line[left][2] + line[right][2]) * rem; \
bulk[3] = (acc[3] << 8) + (line[left][3] + line[right][3]) * rem;
bulk[0] = (acc[0] * ww) + (line[left][0] + line[right][0]) * fw; \
bulk[1] = (acc[1] * ww) + (line[left][1] + line[right][1]) * fw; \
bulk[2] = (acc[2] * ww) + (line[left][2] + line[right][2]) * fw; \
bulk[3] = (acc[3] * ww) + (line[left][3] + line[right][3]) * fw;
#define SAVE(acc) \
(UINT8)((acc[0] + w2) / w) << 0 | (UINT8)((acc[1] + w2) / w) << 8 | \
(UINT8)((acc[2] + w2) / w) << 16 | (UINT8)((acc[3] + w2) / w) << 24
(UINT8)((acc[0] + (1 << 23)) >> 24) << 0 | (UINT8)((acc[1] + (1 << 23)) >> 24) << 8 | \
(UINT8)((acc[2] + (1 << 23)) >> 24) << 16 | (UINT8)((acc[3] + (1 << 23)) >> 24) << 24
ImagingSectionEnter(&cookie);
@ -116,6 +115,10 @@ HorizontalBoxBlur32(Imaging im, Imaging imOut, float floatRadius)
ImagingSectionLeave(&cookie);
#undef MOVE_ACC
#undef ADD_FAR
#undef SAVE
return imOut;
}
@ -133,13 +136,22 @@ HorizontalBoxBlur8(Imaging im, Imaging imOut, float floatRadius)
int lastx = im->xsize - 1;
int radius = (int) floatRadius;
UINT8 rem = (UINT8) (256 * (floatRadius - radius));
int w = 256 * (radius * 2 + 1) + rem * 2;
int w2 = w / 2;
UINT32 ww = (UINT32) (1 << 24) / (floatRadius * 2 + 1);
UINT32 fw = ((1 << 24) - (radius * 2 + 1) * ww) / 2;
int edgeA = MIN(radius + 1, im->xsize);
int edgeB = MAX(im->xsize - radius - 1, 0);
#define MOVE_ACC(acc, substract, add) \
acc += line[add] - line[substract];
#define ADD_FAR(bulk, acc, left, right) \
bulk = (acc * ww) + (line[left] + line[right]) * fw;
#define SAVE(acc) \
(UINT8)((acc + (1 << 23)) >> 24)
ImagingSectionEnter(&cookie);
for (y = 0; y < im->ysize; y++) {
@ -154,43 +166,47 @@ HorizontalBoxBlur8(Imaging im, Imaging imOut, float floatRadius)
if (edgeA <= edgeB)
{
for (x = 0; x < edgeA; x++) {
acc = acc + line[x + radius] - line[0];
bulk = (acc << 8) + (line[0] + line[x + radius + 1]) * rem;
imOut->image8[x][y] = (UINT8)((bulk + w2) / w);
MOVE_ACC(acc, 0, x + radius);
ADD_FAR(bulk, acc, 0, x + radius + 1);
imOut->image8[x][y] = SAVE(bulk);
}
for (x = edgeA; x < edgeB; x++) {
acc = acc + line[x + radius] - line[x - radius - 1];
bulk = (acc << 8) + (line[x - radius - 1] + line[x + radius + 1]) * rem;
imOut->image8[x][y] = (UINT8)((bulk + w2) / w);
MOVE_ACC(acc, x - radius - 1, x + radius);
ADD_FAR(bulk, acc, x - radius - 1, x + radius + 1);
imOut->image8[x][y] = SAVE(bulk);
}
for (x = edgeB; x < im->xsize; x++) {
acc = acc + line[lastx] - line[x - radius - 1];
bulk = (acc << 8) + (line[x - radius - 1] + line[lastx]) * rem;
imOut->image8[x][y] = (UINT8)((bulk + w2) / w);
MOVE_ACC(acc, x - radius - 1, lastx);
ADD_FAR(bulk, acc, x - radius - 1, lastx);
imOut->image8[x][y] = SAVE(bulk);
}
}
else
{
for (x = 0; x < edgeB; x++) {
acc = acc + line[x + radius] - line[0];
bulk = (acc << 8) + (line[0] + line[x + radius + 1]) * rem;
imOut->image8[x][y] = (UINT8)((bulk + w2) / w);
MOVE_ACC(acc, 0, x + radius);
ADD_FAR(bulk, acc, 0, x + radius + 1);
imOut->image8[x][y] = SAVE(bulk);
}
for (x = edgeB; x < edgeA; x++) {
acc = acc + line[lastx] - line[0];
bulk = (acc << 8) + (line[0] + line[lastx]) * rem;
imOut->image8[x][y] = (UINT8)((bulk + w2) / w);
MOVE_ACC(acc, 0, lastx);
ADD_FAR(bulk, acc, 0, lastx);
imOut->image8[x][y] = SAVE(bulk);
}
for (x = edgeA; x < im->xsize; x++) {
acc = acc + line[lastx] - line[x - radius - 1];
bulk = (acc << 8) + (line[x - radius - 1] + line[lastx]) * rem;
imOut->image8[x][y] = (UINT8)((bulk + w2) / w);
MOVE_ACC(acc, x - radius - 1, lastx);
ADD_FAR(bulk, acc, x - radius - 1, lastx);
imOut->image8[x][y] = SAVE(bulk);
}
}
}
ImagingSectionLeave(&cookie);
#undef MOVE_ACC
#undef ADD_FAR
#undef SAVE
return imOut;
}