/* for >= 8, then use O(log n) memcpy's... */
else {
- gint len = 4;
- gint lenbytes = 4 * sizeof(RrPixel32);
+ gchar *cdest;
+ gint lenbytes;
/* copy the first 3 * 32 bits (3 words) ourselves - then we have
3 + the original 1 = 4 words to make copies of at a time
for (x = 3; x > 0; --x)
*(dest++) = *start;
- for (x = w - 4; x > 0;) {
- memcpy(dest, start, lenbytes);
- x -= len;
- dest += len;
- len <<= 1;
+ /* cdest is a pointer to the pixel data that is typed char* so that
+ adding 1 to its position moves it only one byte
+
+ lenbytes is the amount of bytes that we will be copying each
+ iteration. this doubles each time through the loop.
+
+ x is the number of bytes left to copy into. lenbytes will alwaysa
+ be bounded by x
+
+ this loop will run O(log n) times (n is the number of bytes we
+ need to copy into), since the size of the copy is doubled each
+ iteration. it seems that gcc does some nice optimizations to make
+ this memcpy very fast on hardware with support for vector operations
+ such as mmx or see. here is an idea of the kind of speed up we are
+ getting by doing this (splitvertical3 switches from doing
+ "*(data++) = color" n times to doing this memcpy thing log n times:
+
+ % cumulative self self total
+ time seconds seconds calls ms/call ms/call name
+ 49.44 0.88 0.88 1063 0.83 0.83 splitvertical1
+ 47.19 1.72 0.84 1063 0.79 0.79 splitvertical2
+ 2.81 1.77 0.05 1063 0.05 0.05 splitvertical3
+ */
+ cdest = (gchar*)dest;
+ lenbytes = 4 * sizeof(RrPixel32);
+ for (x = (w - 4) * sizeof(RrPixel32); x > 0;) {
+ memcpy(cdest, start, lenbytes);
+ x -= lenbytes;
+ cdest += lenbytes;
lenbytes <<= 1;
- if (len > x) {
- len = x;
- lenbytes = x * sizeof(RrPixel32);
- }
+ if (lenbytes > x)
+ lenbytes = x;
}
}
}
static void gradient_horizontal(RrSurface *sf, gint w, gint h)
{
- gint x, y;
+ gint x, y, cpbytes;
RrPixel32 *data = sf->pixel_data, *datav;
+ gchar *datac;
VARS(x);
SETUP(x, sf->primary, sf->secondary, w);
+ /* set the color values for the first row */
datav = data;
for (x = w - 1; x > 0; --x) { /* 0 -> w - 1 */
*datav = COLOR(x);
*datav = COLOR(x);
++datav;
- for (y = h - 1; y > 0; --y) { /* 1 -> h */
- memcpy(datav, data, w * sizeof(RrPixel32));
- datav += w;
+ /* copy the first row to the rest in O(logn) copies */
+ datac = (gchar*)datav;
+ cpbytes = 1 * w * sizeof(RrPixel32);
+ for (y = (h - 1) * w * sizeof(RrPixel32); y > 0;) {
+ memcpy(datac, data, cpbytes);
+ y -= cpbytes;
+ datac += cpbytes;
+ cpbytes <<= 1;
+ if (cpbytes > y)
+ cpbytes = y;
}
}
static void gradient_mirrorhorizontal(RrSurface *sf, gint w, gint h)
{
- gint x, y, half1, half2;
+ gint x, y, half1, half2, cpbytes;
RrPixel32 *data = sf->pixel_data, *datav;
+ gchar *datac;
VARS(x);
half1 = (w + 1) / 2;
half2 = w / 2;
+ /* set the color values for the first row */
+
SETUP(x, sf->primary, sf->secondary, half1);
datav = data;
for (x = half1 - 1; x > 0; --x) { /* 0 -> half1 - 1 */
++datav;
}
- for (y = h - 1; y > 0; --y) { /* 1 -> h */
- memcpy(datav, data, w * sizeof(RrPixel32));
- datav += w;
+ /* copy the first row to the rest in O(logn) copies */
+ datac = (gchar*)datav;
+ cpbytes = 1 * w * sizeof(RrPixel32);
+ for (y = (h - 1) * w * sizeof(RrPixel32); y > 0;) {
+ memcpy(datac, data, cpbytes);
+ y -= cpbytes;
+ datac += cpbytes;
+ cpbytes <<= 1;
+ if (cpbytes > y)
+ cpbytes = y;
}
}
}
}
-
static void gradient_diagonal(RrSurface *sf, gint w, gint h)
{
gint x, y;
*data = COLOR(x);
}
-static void gradient_pyramid(RrSurface *sf, gint inw, gint inh)
+static void gradient_pyramid(RrSurface *sf, gint w, gint h)
{
- gint x, y, w = (inw >> 1) + 1, h = (inh >> 1) + 1;
- RrPixel32 *data = sf->pixel_data;
- RrPixel32 *end = data + inw*inh - 1;
- RrPixel32 current;
+ RrPixel32 *ldata, *rdata;
+ RrPixel32 *cp;
RrColor left, right;
RrColor extracorner;
+ gint x, y, halfw, halfh, midx, midy;
VARS(lefty);
VARS(righty);
extracorner.g = (sf->primary->g + sf->secondary->g) / 2;
extracorner.b = (sf->primary->b + sf->secondary->b) / 2;
- SETUP(lefty, (&extracorner), sf->secondary, h);
- SETUP(righty, sf->primary, (&extracorner), h);
+ halfw = w >> 1;
+ halfh = h >> 1;
+ midx = w - halfw - halfw; /* 0 or 1, depending if w is even or odd */
+ midy = h - halfh - halfh; /* 0 or 1, depending if h is even or odd */
+
+ SETUP(lefty, sf->primary, (&extracorner), halfh + midy);
+ SETUP(righty, (&extracorner), sf->secondary, halfh + midy);
+
+ /* draw the top half
+
+ it is faster to draw both top quarters together than to draw one and
+ then copy it over to the other side.
+ */
+
+ ldata = sf->pixel_data;
+ rdata = ldata + w - 1;
+ for (y = halfh + midy; y > 0; --y) { /* 0 -> (h+1)/2 */
+ RrPixel32 c;
- for (y = h - 1; y > 0; --y) { /* 0 -> h-1 */
COLOR_RR(lefty, (&left));
COLOR_RR(righty, (&right));
- SETUP(x, (&left), (&right), w);
+ SETUP(x, (&left), (&right), halfw + midx);
- for (x = w - 1; x > 0; --x) { /* 0 -> w-1 */
- current = COLOR(x);
- *(data+x) = current;
- *(data+inw-x) = current;
- *(end-x) = current;
- *(end-(inw-x)) = current;
+ for (x = halfw + midx - 1; x > 0; --x) { /* 0 -> (w+1)/2 */
+ c = COLOR(x);
+ *(ldata++) = *(rdata--) = c;
NEXT(x);
}
- current = COLOR(x);
- *(data+x) = current;
- *(data+inw-x) = current;
- *(end-x) = current;
- *(end-(inw-x)) = current;
-
- data+=inw;
- end-=inw;
+ c = COLOR(x);
+ *ldata = *rdata = c;
+ ldata += halfw + 1;
+ rdata += halfw - 1 + midx + w;
NEXT(lefty);
NEXT(righty);
}
- COLOR_RR(lefty, (&left));
- COLOR_RR(righty, (&right));
- SETUP(x, (&left), (&right), w);
+ /* copy the top half into the bottom half, mirroring it, so we can only
+ copy one row at a time
- for (x = w - 1; x > 0; --x) { /* 0 -> w-1 */
- current = COLOR(x);
- *(data+x) = current;
- *(data+inw-x) = current;
- *(end-x) = current;
- *(end-(inw-x)) = current;
+ it is faster, to move the writing pointer forward, and the reading
+ pointer backward
- NEXT(x);
+ this is the current code, moving the write pointer forward and read
+ pointer backward
+ 41.78 4.26 1.78 504 3.53 3.53 gradient_pyramid2
+ this is the opposite, moving the read pointer forward and the write
+ pointer backward
+ 42.27 4.40 1.86 504 3.69 3.69 gradient_pyramid2
+
+ */
+ ldata = sf->pixel_data + (halfh - 1) * w;
+ cp = ldata + (midy + 1) * w;
+ for (y = halfh; y > 0; --y) {
+ memcpy(cp, ldata, w * sizeof(RrPixel32));
+ ldata -= w;
+ cp += w;
}
- current = COLOR(x);
- *(data+x) = current;
- *(data+inw-x) = current;
- *(end-x) = current;
- *(end-(inw-x)) = current;
}
-
projects / chaz / openbox / blobdiff