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WebSVN – planix.SVN – Blame – /os/branches/feature-vt/sys/src/libmemdraw/read.c – Rev 2

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#include <u.h>
2 
#include <libc.h>
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#include <draw.h>
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#include <memdraw.h>
5 
 
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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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	}
61 
 
62 
	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);
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");
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		return nil;
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	}
70 
 
71 
	miny = r.min.y;
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	maxy = r.max.y;
73 
 
74 
	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;
84 
	while(maxy > miny){
85 
		dy = maxy - miny;
86 
		if(dy*l > chunk)
87 
			dy = chunk/l;
88 
		if(dy <= 0){
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			werrstr("readmemimage: image too wide for buffer");
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			goto Err;
91 
		}
92 
		n = dy*l;
93 
		m = readn(fd, tmp, n);
94 
		if(m != n){
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			werrstr("readmemimage: read count %d not %d: %r", m, n);
96 
   Err:
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 			freememimage(i);
98 
			free(tmp);
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			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 
}