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