112 lines
2.1 KiB
C
112 lines
2.1 KiB
C
#include <u.h>
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#include <libc.h>
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#include <draw.h>
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#include <memdraw.h>
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Memimage*
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readmemimage(int fd)
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{
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char hdr[5*12+1];
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int dy;
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ulong chan;
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uint l, n;
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int m, j;
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int new, miny, maxy;
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Rectangle r;
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uchar *tmp;
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int ldepth, chunk;
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Memimage *i;
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if(readn(fd, hdr, 11) != 11){
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werrstr("readimage: short header");
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return nil;
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}
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if(memcmp(hdr, "compressed\n", 11) == 0)
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return creadmemimage(fd);
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if(readn(fd, hdr+11, 5*12-11) != 5*12-11){
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werrstr("readimage: short header (2)");
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return nil;
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}
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/*
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* distinguish new channel descriptor from old ldepth.
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* channel descriptors have letters as well as numbers,
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* while ldepths are a single digit formatted as %-11d.
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*/
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new = 0;
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for(m=0; m<10; m++){
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if(hdr[m] != ' '){
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new = 1;
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break;
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}
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}
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if(hdr[11] != ' '){
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werrstr("readimage: bad format");
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return nil;
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}
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if(new){
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hdr[11] = '\0';
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if((chan = strtochan(hdr)) == 0){
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werrstr("readimage: bad channel string %s", hdr);
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return nil;
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}
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}else{
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ldepth = ((int)hdr[10])-'0';
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if(ldepth<0 || ldepth>3){
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werrstr("readimage: bad ldepth %d", ldepth);
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return nil;
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}
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chan = drawld2chan[ldepth];
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}
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r.min.x = atoi(hdr+1*12);
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r.min.y = atoi(hdr+2*12);
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r.max.x = atoi(hdr+3*12);
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r.max.y = atoi(hdr+4*12);
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if(r.min.x>r.max.x || r.min.y>r.max.y){
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werrstr("readimage: bad rectangle");
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return nil;
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}
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miny = r.min.y;
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maxy = r.max.y;
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l = bytesperline(r, chantodepth(chan));
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i = allocmemimage(r, chan);
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if(i == nil)
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return nil;
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chunk = 32*1024;
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if(chunk < l)
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chunk = l;
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tmp = malloc(chunk);
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if(tmp == nil)
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goto Err;
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while(maxy > miny){
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dy = maxy - miny;
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if(dy*l > chunk)
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dy = chunk/l;
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if(dy <= 0){
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werrstr("readmemimage: image too wide for buffer");
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goto Err;
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}
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n = dy*l;
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m = readn(fd, tmp, n);
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if(m != n){
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werrstr("readmemimage: read count %d not %d: %r", m, n);
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Err:
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freememimage(i);
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free(tmp);
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return nil;
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}
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if(!new) /* an old image: must flip all the bits */
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for(j=0; j<chunk; j++)
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tmp[j] ^= 0xFF;
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if(loadmemimage(i, Rect(r.min.x, miny, r.max.x, miny+dy), tmp, chunk) <= 0)
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goto Err;
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miny += dy;
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}
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free(tmp);
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return i;
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}
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