1 files changed, 88 insertions, 0 deletions
diff --git a/src/lib9/fmt/charstod.c b/src/lib9/fmt/charstod.c
new file mode 100644
index 000000000..b8096e8fb
--- /dev/null
+++ b/src/lib9/fmt/charstod.c
@@ -0,0 +1,88 @@
+/*
+ * The authors of this software are Rob Pike and Ken Thompson,
+ * with contributions from Mike Burrows and Sean Dorward.
+ *
+ *     Copyright (c) 2002-2006 by Lucent Technologies.
+ *     Portions Copyright (c) 2004 Google Inc.
+ * 
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose without fee is hereby granted, provided that this entire notice
+ * is included in all copies of any software which is or includes a copy
+ * or modification of this software and in all copies of the supporting
+ * documentation for such software.
+ * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED
+ * WARRANTY.  IN PARTICULAR, NEITHER THE AUTHORS NOR LUCENT TECHNOLOGIES 
+ * NOR GOOGLE INC MAKE ANY REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING 
+ * THE MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.
+ */
+
+#include <u.h>
+#include <libc.h>
+#include "fmtdef.h"
+
+/*
+ * Reads a floating-point number by interpreting successive characters
+ * returned by (*f)(vp).  The last call it makes to f terminates the
+ * scan, so is not a character in the number.  It may therefore be
+ * necessary to back up the input stream up one byte after calling charstod.
+ */
+
+double
+fmtcharstod(int(*f)(void*), void *vp)
+{
+	double num, dem;
+	int neg, eneg, dig, exp, c;
+
+	num = 0;
+	neg = 0;
+	dig = 0;
+	exp = 0;
+	eneg = 0;
+
+	c = (*f)(vp);
+	while(c == ' ' || c == '\t')
+		c = (*f)(vp);
+	if(c == '-' || c == '+'){
+		if(c == '-')
+			neg = 1;
+		c = (*f)(vp);
+	}
+	while(c >= '0' && c <= '9'){
+		num = num*10 + c-'0';
+		c = (*f)(vp);
+	}
+	if(c == '.')
+		c = (*f)(vp);
+	while(c >= '0' && c <= '9'){
+		num = num*10 + c-'0';
+		dig++;
+		c = (*f)(vp);
+	}
+	if(c == 'e' || c == 'E'){
+		c = (*f)(vp);
+		if(c == '-' || c == '+'){
+			if(c == '-'){
+				dig = -dig;
+				eneg = 1;
+			}
+			c = (*f)(vp);
+		}
+		while(c >= '0' && c <= '9'){
+			exp = exp*10 + c-'0';
+			c = (*f)(vp);
+		}
+	}
+	exp -= dig;
+	if(exp < 0){
+		exp = -exp;
+		eneg = !eneg;
+	}
+	dem = __fmtpow10(exp);
+	if(eneg)
+		num /= dem;
+	else
+		num *= dem;
+	if(neg)
+		return -num;
+	return num;
+}