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authorOndřej Surý <ondrej@sury.org>2011-09-13 13:13:40 +0200
committerOndřej Surý <ondrej@sury.org>2011-09-13 13:13:40 +0200
commit5ff4c17907d5b19510a62e08fd8d3b11e62b431d (patch)
treec0650497e988f47be9c6f2324fa692a52dea82e1 /src/lib9/fmt/charstod.c
parent80f18fc933cf3f3e829c5455a1023d69f7b86e52 (diff)
downloadgolang-upstream/60.tar.gz
Imported Upstream version 60upstream/60
Diffstat (limited to 'src/lib9/fmt/charstod.c')
-rw-r--r--src/lib9/fmt/charstod.c88
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
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+++ 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;
+}