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#include <u.h>
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#include <libc.h>
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#include <draw.h>
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static char channames[] = "rgbkamx";
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char*
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chantostr(char *buf, ulong cc)
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{
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	ulong c, rc;
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	char *p;
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	if(chantodepth(cc) == 0)
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		return nil;
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	/* reverse the channel descriptor so we can easily generate the string in the right order */
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	rc = 0;
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	for(c=cc; c; c>>=8){
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		rc <<= 8;
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		rc |= c&0xFF;
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	}
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	p = buf;
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	for(c=rc; c; c>>=8) {
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		*p++ = channames[TYPE(c)];
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		*p++ = '0'+NBITS(c);
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	}
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	*p = 0;
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	return buf;
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}
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/* avoid pulling in ctype when using with drawterm etc. */
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static int
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isspace(char c)
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{
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	return c==' ' || c== '\t' || c=='\r' || c=='\n';
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}
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ulong
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strtochan(char *s)
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{
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	char *p, *q;
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	ulong c;
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	int t, n, d;
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	c = 0;
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	d = 0;
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	p=s;
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	while(*p && isspace(*p))
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		p++;
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	while(*p && !isspace(*p)){
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		if((q = strchr(channames, p[0])) == nil)
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			return 0;
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		t = q-channames;
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		if(p[1] < '0' || p[1] > '9')
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			return 0;
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		n = p[1]-'0';
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		d += n;
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		c = (c<<8) | __DC(t, n);
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		p += 2;
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	}
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	if(d==0 || (d>8 && d%8) || (d<8 && 8%d))
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		return 0;
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	return c;
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}
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int
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chantodepth(ulong c)
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{
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	int n;
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	for(n=0; c; c>>=8){
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		if(TYPE(c) >= NChan || NBITS(c) > 8 || NBITS(c) <= 0)
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			return 0;
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		n += NBITS(c);
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	}
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	if(n==0 || (n>8 && n%8) || (n<8 && 8%n))
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		return 0;
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	return n;
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}