1 files changed, 77 insertions, 0 deletions
diff --git a/src/libdraw/chan.c b/src/libdraw/chan.c
new file mode 100644
index 00000000..3b76a32a
--- /dev/null
+++ b/src/libdraw/chan.c
@@ -0,0 +1,77 @@
+#include <u.h>
+#include <libc.h>
+#include <draw.h>
+
+static char channames[] = "rgbkamx";
+char*
+chantostr(char *buf, u32int cc)
+{
+	u32int 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 int
+isspace(char c)
+{
+	return c==' ' || c== '\t' || c=='\r' || c=='\n';
+}
+
+u32int
+strtochan(char *s)
+{
+	char *p, *q;
+	u32int c;
+	int t, n;
+
+	c = 0;
+	p=s;
+	while(*p && isspace(*p))
+		p++;
+
+	while(*p && !isspace(*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';
+		c = (c<<8) | __DC(t, n);
+		p += 2;
+	}
+	return c;
+}
+
+int
+chantodepth(u32int 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;
+}