1 #include <u.h>
2 #include <libc.h>
3 #include <draw.h>
4 #include <memdraw.h>
5 
6 Memimage*
7 readmemimage(int fd)
8 {
9 	char hdr[5*12+1];
10 	int dy;
11 	u32int chan;
12 	uint l, n;
13 	int m, j;
14 	int new, miny, maxy;
15 	Rectangle r;
16 	uchar *tmp;
17 	int ldepth, chunk;
18 	Memimage *i;
19 
20 	if(readn(fd, hdr, 11) != 11){
21 		werrstr("readimage: short header");
22 		return nil;
23 	}
24 	if(memcmp(hdr, "compressed\n", 11) == 0)
25 		return creadmemimage(fd);
26 	if(readn(fd, hdr+11, 5*12-11) != 5*12-11){
27 		werrstr("readimage: short header (2)");
28 		return nil;
29 	}
30 
31 	/*
32 	 * distinguish new channel descriptor from old ldepth.
33 	 * channel descriptors have letters as well as numbers,
34 	 * while ldepths are a single digit formatted as %-11d.
35 	 */
36 	new = 0;
37 	for(m=0; m<10; m++){
38 		if(hdr[m] != ' '){
39 			new = 1;
40 			break;
41 		}
42 	}
43 	if(hdr[11] != ' '){
44 		werrstr("readimage: bad format");
45 		return nil;
46 	}
47 	if(new){
48 		hdr[11] = '\0';
49 		if((chan = strtochan(hdr)) == 0){
50 			werrstr("readimage: bad channel string %s", hdr);
51 			return nil;
52 		}
53 	}else{
54 		ldepth = ((int)hdr[10])-'0';
55 		if(ldepth<0 || ldepth>3){
56 			werrstr("readimage: bad ldepth %d", ldepth);
57 			return nil;
58 		}
59 		chan = drawld2chan[ldepth];
60 	}
61 
62 	r.min.x = atoi(hdr+1*12);
63 	r.min.y = atoi(hdr+2*12);
64 	r.max.x = atoi(hdr+3*12);
65 	r.max.y = atoi(hdr+4*12);
66 	if(r.min.x>r.max.x || r.min.y>r.max.y){
67 		werrstr("readimage: bad rectangle");
68 		return nil;
69 	}
70 
71 	miny = r.min.y;
72 	maxy = r.max.y;
73 
74 	l = bytesperline(r, chantodepth(chan));
75 	i = allocmemimage(r, chan);
76 	if(i == nil)
77 		return nil;
78 	chunk = 32*1024;
79 	if(chunk < l)
80 		chunk = l;
81 	tmp = malloc(chunk);
82 	if(tmp == nil)
83 		goto Err;
84 	while(maxy > miny){
85 		dy = maxy - miny;
86 		if(dy*l > chunk)
87 			dy = chunk/l;
88 		if(dy <= 0){
89 			werrstr("readmemimage: image too wide for buffer");
90 			goto Err;
91 		}
92 		n = dy*l;
93 		m = readn(fd, tmp, n);
94 		if(m != n){
95 			werrstr("readmemimage: read count %d not %d: %r", m, n);
96    Err:
97  			freememimage(i);
98 			free(tmp);
99 			return nil;
100 		}
101 		if(!new)	/* an old image: must flip all the bits */
102 			for(j=0; j<chunk; j++)
103 				tmp[j] ^= 0xFF;
104 
105 		if(loadmemimage(i, Rect(r.min.x, miny, r.max.x, miny+dy), tmp, chunk) <= 0)
106 			goto Err;
107 		miny += dy;
108 	}
109 	free(tmp);
110 	return i;
111 }