ref: e391b7ec8c0dc746a70725f3fc598def0419d1e6
dir: /sys/src/libdraw/writecolmap.c/
#include <u.h>
#include <libc.h>
#include <draw.h>
/*
* This code (and the devdraw interface) will have to change
* if we ever get bitmaps with ldepth > 3, because the
* colormap will have to be written in chunks
*/
void
writecolmap(Display *d, RGB *m)
{
int i, n, fd;
char buf[64], *t;
ulong r, g, b;
sprint(buf, "/dev/draw/%d/colormap", d->dirno);
fd = open(buf, OWRITE|OCEXEC);
if(fd < 0)
drawerror(d, "writecolmap: open colormap failed");
t = malloc(8192);
if (t == nil)
drawerror(d, "writecolmap: no memory");
n = 0;
for(i = 0; i < 256; i++) {
r = m[i].red>>24;
g = m[i].green>>24;
b = m[i].blue>>24;
n += sprint(t+n, "%d %lud %lud %lud\n", 255-i, r, g, b);
}
i = write(fd, t, n);
free(t);
close(fd);
if(i != n)
drawerror(d, "writecolmap: bad write");
}