* int getcmap(int id, char *file, unsigned char *buf)

#include <u.h>
#include <libc.h>
#include <draw.h>

/*
* int getcmap(int id, char *file, unsigned char *buf)
* Read a colormap from the given file into the buffer.
* Returns 1 on success, 0 otherwise.
* Goes to unglaublich length to figure out what the file name means:
* If the name is "screen" or "display" or "vga", reads the colormap from /dev/draw/id/colormap.
* If the name is "gamma",returns gamma=2.3 colormap
* If the name is "gamma###", returns gamma=#### colormap
* Ditto for rgamma, for reverse video.
* Looks for the file in a list of directories (given below).
*/

char *cmapdir[] = {
"",
"/lib/cmap/",
0
};

int
getcmap(int id, char *f, unsigned char *buf)
{
char name[512];
char *s, *lines[256], *fields[4];
int cmap, i, j, n, v, rev;
double gamma;

cmap = -1;
for(i=0; cmapdir[i]!=nil ;i++){
snprint(name, sizeof name, "%s%s", cmapdir[i], f);
if((cmap = open(name, OREAD)) >= 0)
break;
}

if(cmap == -1){
if(strcmp(name, "screen")==0 || strcmp(name, "display")==0 || strcmp(name, "vga")==0){
snprint(name, sizeof name, "/dev/draw/%d/colormap", id);
cmap = open(name, OREAD);
if(cmap < 0)
return 0;
}
}

if(cmap==-1){ /* could be gamma or gamma<number> or fb */
if(strncmp(f, "gamma", 5)==0){
rev=0;
f+=5;
}else if(strncmp(f, "rgamma", 6)==0){
rev = 1;
f+=6;
}else
return 0;
if(*f == '\0')
gamma=2.3;
else{
if(strspn(f, "0123456789.") != strlen(f))
return 0;
gamma = atof(f);
}
for(i=0; i!=256; i++){
v=255.*pow(i/255., 1./gamma);
if(rev)
v=255-v;
buf[0] = buf[1] = buf[2] = v;
buf += 3;
}
return 1;
}

s = malloc(20000);
n = readn(cmap, s, 20000-1);
if(n <= 0)
return 0;
s[n] = '\0';
if(getfields(s, lines, 256, 0, "\n") != 256)
return 0;
for(i=0; i<256; i++){
if(getfields(lines[i], fields, 4, 1, " \t") != 4)
return 0;
if(atoi(fields[0]) != i)
return 0;
for(j=0; j<3; j++)
buf[3*i+j] = atoi(fields[j+1]);
}
return 1;
}

/* replicate (from top) value in v (n bits) until it fills a ulong */
ulong
rep(ulong v, int n)
{
int o;
ulong rv;

rv = 0;
for(o=32-n; o>=0; o-=n)
rv |= v<<o;
if(o != -n)
rv |= v>>-o;
return rv;
}

void
putcmap(int id, uchar cmap[256*3])
{
char *s, *t;
int i, fd;
char name[64];

snprint(name, sizeof name, "/dev/draw/%d/colormap", id);
fd = open(name, OWRITE);
if(fd < 0)
sysfatal("can't open colormap file: %r");
s = malloc(20000);
t = s;
for(i = 0; i<256; i++)
t += sprint(t, "%d %d %d %d\n", i, cmap[3*i+0], cmap[3*i+1], cmap[3*i+2]);
if(write(fd, s, t-s) != t-s)
sysfatal("writing color map: %r");
close(fd);
}

void
main(int argc, char *argv[])
{
uchar cmapbuf[256*3];
char *map, buf[12*12+1];
int fd, id;

if(argc>2){
fprint(2, "Usage: %s colormap\n", argv[0]);
exits("usage");
}
map = "rgbv";
if(argc > 1)
map = argv[1];

fd = open("/dev/draw/new", OREAD);
if(fd < 0 || read(fd, buf, sizeof buf) != 12*12)
sysfatal("can't connect to display: %r");
id = atoi(buf+0*12);
if(strncmp(buf+2*12, " m8 ", 12) != 0)
sysfatal("can't set colormap except on CMAP8 (m8) displays; this one is %.12s", buf+2*12);

if(getcmap(id, map, cmapbuf) == 0){
fprint(2, "%s: can't find %s\n", argv[0], map);
exits("not found");
}

putcmap(id, cmapbuf);
exits(0);
}