ref: 0922923b6268490b89a24c1b4cc7316a34daea16
parent: 272bc8e3488ce5c7220ebf7cc731a04211b6dba4
author: Quentin Rameau <[email protected]>
date: Sun Dec 23 12:41:39 EST 2018
[libc] Add strtoul
--- a/src/libc/stdlib/Makefile
+++ b/src/libc/stdlib/Makefile
@@ -19,6 +19,7 @@
qsort.o\
rand.o\
realloc.o\
+ strtoul.o\
strtoull.o\
all: $(OBJS)
--- /dev/null
+++ b/src/libc/stdlib/strtoul.c
@@ -1,0 +1,64 @@
+#include <ctype.h>
+#include <errno.h>
+#include <limits.h>
+#include <stdlib.h>
+#include <string.h>
+
+#undef strtoul
+
+unsigned long
+strtoul(const char *s, char **end, int base)
+{+ int d, sign = 1;
+ unsigned long n;
+ static const char digits[] = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+ const char *t, *p;
+
+ while (isspace(*s))
+ ++s;
+
+ switch (*s) {+ case '-':
+ sign = -1;
+ case '+':
+ ++s;
+ }
+
+ if (base == 0) {+ if (*s == '0' && toupper(s[1]) == 'X')
+ base = 16;
+ else if (*s == '0')
+ base = 8;
+ else
+ base = 10;
+ }
+
+ if (base == 16 && *s == '0' && toupper(s[1]) == 'X')
+ s += 2;
+
+ n = 0;
+ for (t = s; p = strchr(digits, toupper(*t)); ++t) {+ if ((d = p - digits) >= base)
+ break;
+ if (n > ULONG_MAX/base)
+ goto overflow;
+ n *= base;
+ if (d > ULONG_MAX - n)
+ goto overflow;
+ n += d;
+ }
+
+
+ if (end)
+ *end = t;
+ if (n == 0 && s == t)
+ errno = EINVAL;
+ return n*sign;
+
+overflow:
+ if (end)
+ *end = t;
+ errno = ERANGE;
+
+ return ULONG_MAX;
+}