From 4e09bca9e34c226b6d7e34b4fa11248405fd988e Mon Sep 17 00:00:00 2001
From: Anton Kling <anton@kling.gg>
Date: Sun, 22 Oct 2023 19:50:38 +0200
Subject: Move everything into a new repo.

---
 userland/libc/stdlib/strtoul.c | 72 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 72 insertions(+)
 create mode 100644 userland/libc/stdlib/strtoul.c

(limited to 'userland/libc/stdlib/strtoul.c')

diff --git a/userland/libc/stdlib/strtoul.c b/userland/libc/stdlib/strtoul.c
new file mode 100644
index 0000000..4d9a51d
--- /dev/null
+++ b/userland/libc/stdlib/strtoul.c
@@ -0,0 +1,72 @@
+#include <assert.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <limits.h>
+
+extern int errno;
+int get_value(char c, long base) {
+  int r;
+  if (c >= '0' && c <= '9')
+    r = c - '0';
+  else if (c >= 'A' && c <= 'Z')
+    r = c - 'A';
+  else if (c >= 'a' && c <= 'z')
+    r = c - 'a';
+  else
+    return -1;
+  if (r >= base)
+    return -1;
+  return r;
+}
+
+// https://pubs.opengroup.org/onlinepubs/9699919799/functions/strtoul.html
+unsigned long strtoul(const char *restrict str, char **restrict endptr,
+                      int base) {
+  unsigned long ret_value = 0;
+  if (endptr)
+    *endptr = str;
+  // Ignore inital white-space sequence
+  for (; *str && isspace(*str); str++)
+    ;
+  if (!*str)
+    return ret_value;
+
+  int sign = 0;
+  if ('-' == *str) {
+    // FIXME
+    sign = 1;
+    str++;
+    assert(0);
+  } else if ('+' == *str) {
+    str++;
+  }
+
+  if (0 == base) {
+    // FIXME
+    assert(0);
+  }
+
+  if (2 <= base && 36 >= base) {
+    for (; *str; str++) {
+      ret_value *= base;
+      int val = get_value(*str, base);
+      /*
+      if (-1 == val) {
+        errno = ERANGE;
+        return 0;
+      }*/
+      if (ret_value > ULONG_MAX - val) {
+        errno = ERANGE;
+        return 0;
+      }
+
+      ret_value += val;
+    }
+  } else {
+    errno = EINVAL;
+    return 0;
+  }
+  if (endptr)
+    *endptr = str;
+  return ret_value;
+}
-- 
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