Subversion Repositories planix.SVN

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

Memimage*
readmemimage(int fd)
{
        char hdr[5*12+1];
        int dy;
        ulong chan;
        uint l, n;
        int m, j;
        int new, miny, maxy;
        Rectangle r;
        uchar *tmp;
        int ldepth, chunk;
        Memimage *i;

        if(readn(fd, hdr, 11) != 11){
                werrstr("readimage: short header");
                return nil;
        }
        if(memcmp(hdr, "compressed\n", 11) == 0)
                return creadmemimage(fd);
        if(readn(fd, hdr+11, 5*12-11) != 5*12-11){
                werrstr("readimage: 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("readimage: bad format");
                return nil;
        }
        if(new){
                hdr[11] = '\0';
                if((chan = strtochan(hdr)) == 0){
                        werrstr("readimage: bad channel string %s", hdr);
                        return nil;
                }
        }else{
                ldepth = ((int)hdr[10])-'0';
                if(ldepth<0 || ldepth>3){
                        werrstr("readimage: 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("readimage: bad rectangle");
                return nil;
        }

        miny = r.min.y;
        maxy = r.max.y;

        l = bytesperline(r, chantodepth(chan));
        i = allocmemimage(r, chan);
        if(i == nil)
                return nil;
        chunk = 32*1024;
        if(chunk < l)
                chunk = l;
        tmp = malloc(chunk);
        if(tmp == nil)
                goto Err;
        while(maxy > miny){
                dy = maxy - miny;
                if(dy*l > chunk)
                        dy = chunk/l;
                if(dy <= 0){
                        werrstr("readmemimage: image too wide for buffer");
                        goto Err;
                }
                n = dy*l;
                m = readn(fd, tmp, n);
                if(m != n){
                        werrstr("readmemimage: read count %d not %d: %r", m, n);
   Err:
                        freememimage(i);
                        free(tmp);
                        return nil;
                }
                if(!new)        /* an old image: must flip all the bits */
                        for(j=0; j<chunk; j++)
                                tmp[j] ^= 0xFF;

                if(loadmemimage(i, Rect(r.min.x, miny, r.max.x, miny+dy), tmp, chunk) <= 0)
                        goto Err;
                miny += dy;
        }
        free(tmp);
        return i;
}