20060303a

1 files changed, 96 insertions, 0 deletions

diff --git a/libkern/strtoul.c b/libkern/strtoul.c
new file mode 100644
index 00000000..bdf2fc08
--- /dev/null
+++ b/libkern/strtoul.c
@@ -0,0 +1,96 @@
+#include <lib9.h>
+
+#define ULONG_MAX	4294967295UL
+
+ulong
+strtoul(char *nptr, char **endptr, int base)
+{
+	char *p;
+	ulong n, nn, m;
+	int c, ovfl, neg, v, ndig;
+
+	p = (char*)nptr;
+	neg = 0;
+	n = 0;
+	ndig = 0;
+	ovfl = 0;
+
+	/*
+	 * White space
+	 */
+	for(;;p++){
+		switch(*p){
+		case ' ':
+		case '\t':
+		case '\n':
+		case '\f':
+		case '\r':
+		case '\v':
+			continue;
+		}
+		break;
+	}
+
+	/*
+	 * Sign
+	 */
+	if(*p=='-' || *p=='+')
+		if(*p++ == '-')
+			neg = 1;
+
+	/*
+	 * Base
+	 */
+	if(base==0){
+		if(*p != '0')
+			base = 10;
+		else{
+			base = 8;
+			if(p[1]=='x' || p[1]=='X')
+				base = 16;
+		}
+	}
+ 	if(base<2 || 36<base)
+		goto Return;
+	if(base==16 && *p=='0'){
+		if(p[1]=='x' || p[1]=='X')
+			if(('0' <= p[2] && p[2] <= '9')
+			 ||('a' <= p[2] && p[2] <= 'f')
+			 ||('A' <= p[2] && p[2] <= 'F'))
+				p += 2;
+	}
+	/*
+	 * Non-empty sequence of digits
+	 */
+	n = 0;
+	m = ULONG_MAX/base;
+	for(;; p++,ndig++){
+		c = *p;
+		v = base;
+		if('0'<=c && c<='9')
+			v = c - '0';
+		else if('a'<=c && c<='z')
+			v = c - 'a' + 10;
+		else if('A'<=c && c<='Z')
+			v = c - 'A' + 10;
+		if(v >= base)
+			break;
+		if(n > m)
+			ovfl = 1;
+		nn = n*base + v;
+		if(nn < n)
+			ovfl = 1;
+		n = nn;
+	}
+
+    Return:
+	if(ndig == 0)
+		p = nptr;
+	if(endptr)
+		*endptr = p;
+	if(ovfl)
+		return ULONG_MAX;
+	if(neg)
+		return -n;
+	return n;
+}