ref: 797626032c7fd9f8ae7402687ad732d485764b49
dir: /libmemdraw/cread.c/
#include <u.h>
#include <libc.h>
#include <draw.h>
#include <memdraw.h>
Memimage*
creadmemimage(int fd)
{
char hdr[5*12+1];
Rectangle r;
int m, nb, miny, maxy, new, ldepth, ncblock;
uchar *buf;
Memimage *i;
ulong chan;
if(readn(fd, hdr, 5*12) != 5*12){
werrstr("readmemimage: short header (2)");
return nil;
}
/*
* distinguish new channel descriptor from old ldepth.
* channel descriptors have letters as well as numbers,
* while ldepths are a single digit formatted as %-11d.
*/
new = 0;
for(m=0; m<10; m++){
if(hdr[m] != ' '){
new = 1;
break;
}
}
if(hdr[11] != ' '){
werrstr("creadimage: bad format");
return nil;
}
if(new){
hdr[11] = '\0';
if((chan = strtochan(hdr)) == 0){
werrstr("creadimage: bad channel string %s", hdr);
return nil;
}
}else{
ldepth = ((int)hdr[10])-'0';
if(ldepth<0 || ldepth>3){
werrstr("creadimage: bad ldepth %d", ldepth);
return nil;
}
chan = drawld2chan[ldepth];
}
r.min.x=atoi(hdr+1*12);
r.min.y=atoi(hdr+2*12);
r.max.x=atoi(hdr+3*12);
r.max.y=atoi(hdr+4*12);
if(r.min.x>r.max.x || r.min.y>r.max.y){
werrstr("creadimage: bad rectangle");
return nil;
}
i = allocmemimage(r, chan);
if(i == nil)
return nil;
ncblock = _compblocksize(r, i->depth);
buf = malloc(ncblock);
if(buf == nil)
goto Errout;
miny = r.min.y;
while(miny != r.max.y){
if(readn(fd, hdr, 2*12) != 2*12){
Shortread:
werrstr("readmemimage: short read");
Errout:
freememimage(i);
free(buf);
return nil;
}
maxy = atoi(hdr+0*12);
nb = atoi(hdr+1*12);
if(maxy<=miny || r.max.y<maxy){
werrstr("readimage: bad maxy %d", maxy);
goto Errout;
}
if(nb<=0 || ncblock<nb){
werrstr("readimage: bad count %d", nb);
goto Errout;
}
if(readn(fd, buf, nb)!=nb)
goto Shortread;
if(!new) /* old image: flip the data bits */
_twiddlecompressed(buf, nb);
cloadmemimage(i, Rect(r.min.x, miny, r.max.x, maxy), buf, nb);
miny = maxy;
}
free(buf);
return i;
}