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bitmap_scale: Optimize by moving division out of the loop.

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This commit is contained in:
Vladimir Serbinenko 2015-02-26 18:13:36 +01:00
parent c5a4e79335
commit dd4889f727
1 changed files with 69 additions and 45 deletions
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114
grub-core/video/bitmap_scale.c
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@ -361,35 +361,46 @@ scale_nn (struct grub_video_bitmap *dst, struct grub_video_bitmap *src)
unsigned dh = dst->mode_info.height; unsigned dh = dst->mode_info.height;
unsigned sw = src->mode_info.width; unsigned sw = src->mode_info.width;
unsigned sh = src->mode_info.height; unsigned sh = src->mode_info.height;
unsigned dstride = dst->mode_info.pitch; int dstride = dst->mode_info.pitch;
unsigned sstride = src->mode_info.pitch; int sstride = src->mode_info.pitch;
/* bytes_per_pixel is the same for both src and dst. */ /* bytes_per_pixel is the same for both src and dst. */
unsigned bytes_per_pixel = dst->mode_info.bytes_per_pixel; int bytes_per_pixel = dst->mode_info.bytes_per_pixel;
unsigned dy, sy, ystep, yfrac, yover;
unsigned sx, xstep, xfrac, xover;
grub_uint8_t *dptr, *dline_end, *sline;
unsigned dy; xstep = sw / dw;
for (dy = 0; dy < dh; dy++) xover = sw % dw;
ystep = sh / dh;
yover = sh % dh;
for (dy = 0, sy = 0, yfrac = 0; dy < dh; dy++, sy += ystep, yfrac += yover)
{ {
unsigned dx; if (yfrac >= dh)
for (dx = 0; dx < dw; dx++) {
yfrac -= dh;
sy++;
}
dptr = ddata + dy * dstride;
dline_end = dptr + dw * bytes_per_pixel;
sline = sdata + sy * sstride;
for (sx = 0, xfrac = 0; dptr < dline_end; sx += xstep, xfrac += xover, dptr += bytes_per_pixel)
{ {
grub_uint8_t *dptr;
grub_uint8_t *sptr; grub_uint8_t *sptr;
unsigned sx; int comp;
unsigned sy;
unsigned comp;
/* Compute the source coordinate that the destination coordinate if (xfrac >= dw)
maps to. Note: sx/sw = dx/dw => sx = sw*dx/dw. */ {
sx = sw * dx / dw; xfrac -= dw;
sy = sh * dy / dh; sx++;
}
/* Get the address of the pixels in src and dst. */ /* Get the address of the pixels in src and dst. */
dptr = ddata + dy * dstride + dx * bytes_per_pixel; sptr = sline + sx * bytes_per_pixel;
sptr = sdata + sy * sstride + sx * bytes_per_pixel;
/* Copy the pixel color value. */ /* Copy the pixel color value. */
for (comp = 0; comp < bytes_per_pixel; comp++) for (comp = 0; comp < bytes_per_pixel; comp++)
dptr[comp] = sptr[comp]; dptr[comp] = sptr[comp];
} }
} }
return GRUB_ERR_NONE; return GRUB_ERR_NONE;
@ -422,27 +433,40 @@ scale_bilinear (struct grub_video_bitmap *dst, struct grub_video_bitmap *src)
int sstride = src->mode_info.pitch; int sstride = src->mode_info.pitch;
/* bytes_per_pixel is the same for both src and dst. */ /* bytes_per_pixel is the same for both src and dst. */
int bytes_per_pixel = dst->mode_info.bytes_per_pixel; int bytes_per_pixel = dst->mode_info.bytes_per_pixel;
unsigned dy, syf, sy, ystep, yfrac, yover;
unsigned sxf, sx, xstep, xfrac, xover;
grub_uint8_t *dptr, *dline_end, *sline;
unsigned dy; xstep = (sw << 8) / dw;
for (dy = 0; dy < dh; dy++) xover = (sw << 8) % dw;
ystep = (sh << 8) / dh;
yover = (sh << 8) % dh;
for (dy = 0, syf = 0, yfrac = 0; dy < dh; dy++, syf += ystep, yfrac += yover)
{ {
unsigned dx; if (yfrac >= dh)
for (dx = 0; dx < dw; dx++) {
yfrac -= dh;
syf++;
}
sy = syf >> 8;
dptr = ddata + dy * dstride;
dline_end = dptr + dw * bytes_per_pixel;
sline = sdata + sy * sstride;
for (sxf = 0, xfrac = 0; dptr < dline_end; sxf += xstep, xfrac += xover, dptr += bytes_per_pixel)
{ {
grub_uint8_t *dptr;
grub_uint8_t *sptr; grub_uint8_t *sptr;
unsigned sx;
unsigned sy;
int comp; int comp;
/* Compute the source coordinate that the destination coordinate if (xfrac >= dw)
maps to. Note: sx/sw = dx/dw => sx = sw*dx/dw. */ {
sx = sw * dx / dw; xfrac -= dw;
sy = sh * dy / dh; sxf++;
}
/* Get the address of the pixels in src and dst. */ /* Get the address of the pixels in src and dst. */
dptr = ddata + dy * dstride + dx * bytes_per_pixel; sx = sxf >> 8;
sptr = sdata + sy * sstride + sx * bytes_per_pixel; sptr = sline + sx * bytes_per_pixel;
/* If we have enough space to do so, use bilinear interpolation. /* If we have enough space to do so, use bilinear interpolation.
Otherwise, fall back to nearest neighbor for this pixel. */ Otherwise, fall back to nearest neighbor for this pixel. */
@ -453,27 +477,27 @@ scale_bilinear (struct grub_video_bitmap *dst, struct grub_video_bitmap *src)
/* Fixed-point .8 numbers representing the fraction of the /* Fixed-point .8 numbers representing the fraction of the
distance in the x (u) and y (v) direction within the distance in the x (u) and y (v) direction within the
box of 4 pixels in the source. */ box of 4 pixels in the source. */
int u = (256 * sw * dx / dw) - (sx * 256); unsigned u = sxf & 0xff;
int v = (256 * sh * dy / dh) - (sy * 256); unsigned v = syf & 0xff;
for (comp = 0; comp < bytes_per_pixel; comp++) for (comp = 0; comp < bytes_per_pixel; comp++)
{ {
/* Get the component's values for the /* Get the component's values for the
four source corner pixels. */ four source corner pixels. */
int f00 = sptr[comp]; unsigned f00 = sptr[comp];
int f10 = sptr[comp + bytes_per_pixel]; unsigned f10 = sptr[comp + bytes_per_pixel];
int f01 = sptr[comp + sstride]; unsigned f01 = sptr[comp + sstride];
int f11 = sptr[comp + sstride + bytes_per_pixel]; unsigned f11 = sptr[comp + sstride + bytes_per_pixel];
/* Count coeffecients. */ /* Count coeffecients. */
int c00 = (256 - u) * (256 - v); unsigned c00 = (256 - u) * (256 - v);
int c10 = u * (256 - v); unsigned c10 = u * (256 - v);
int c01 = (256 - u) * v; unsigned c01 = (256 - u) * v;
int c11 = u * v; unsigned c11 = u * v;
/* Interpolate. */ /* Interpolate. */
int fxy = c00 * f00 + c01 * f01 + c10 * f10 + c11 * f11; unsigned fxy = c00 * f00 + c01 * f01 + c10 * f10 + c11 * f11;
fxy = fxy / (256 * 256); fxy = fxy >> 16;
dptr[comp] = fxy; dptr[comp] = fxy;
} }