a

libc/strtoll.c

@@ -0,0 +1,93 @@
+#include <u.h>
+#include <libc.h>
+#define VLONG_MAX	~(((vlong) 1)<<63)
+#define VLONG_MIN	(((vlong) 1)<<63)
+vlong
+strtoll(const char *nptr, char **endptr, int base)
+{
+	char *p;
+	vlong n, nn, m;
+	int c, ovfl, v, neg, 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){
+		base = 10;
+		if(*p == '0') {
+			base = 8;
+			if(p[1]=='x' || p[1]=='X') {
+				p += 2;
+				base = 16;
+			}
+		}
+	} else
+	if(base==16 && *p=='0') {
+		if(p[1]=='x' || p[1]=='X')
+			p += 2;
+	} else
+	if(base<0 || 36<base)
+		goto Return;
+	/*
+	 * Non-empty sequence of digits
+	 */
+	m = VLONG_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 = (char*)nptr;
+	if(endptr)
+		*endptr = p;
+	if(ovfl){
+		if(neg)
+			return VLONG_MIN;
+		return VLONG_MAX;
+	}
+	if(neg)
+		return -n;
+	return n;
+}