initial commit of lk (little kernel) project
diff --git a/lib/libc/atoi.c b/lib/libc/atoi.c
new file mode 100644
index 0000000..e3dd320
--- /dev/null
+++ b/lib/libc/atoi.c
@@ -0,0 +1,105 @@
+/*
+** Copyright 2001, Travis Geiselbrecht. All rights reserved.
+** Distributed under the terms of the NewOS License.
+*/
+/*
+ * Copyright (c) 2008 Travis Geiselbrecht
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files
+ * (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge,
+ * publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#include <stdlib.h>
+#include <ctype.h>
+
+#define LONG_IS_INT 1
+
+static int hexval(char c)
+{
+ if (c >= '0' && c <= '9')
+ return c - '0';
+ else if (c >= 'a' && c <= 'f')
+ return c - 'a' + 10;
+ else if (c >= 'A' && c <= 'F')
+ return c - 'A' + 10;
+
+ return 0;
+}
+
+int atoi(const char *num)
+{
+#if !LONG_IS_INT
+ // XXX fail
+#else
+ return atol(num);
+#endif
+}
+
+unsigned int atoui(const char *num)
+{
+#if !LONG_IS_INT
+ // XXX fail
+#else
+ return atoul(num);
+#endif
+}
+
+long atol(const char *num)
+{
+ long value = 0;
+ int neg = 0;
+
+ if (num[0] == '0' && num[1] == 'x') {
+ // hex
+ num += 2;
+ while (*num && isxdigit(*num))
+ value = value * 16 + hexval(*num++);
+ } else {
+ // decimal
+ if (num[0] == '-') {
+ neg = 1;
+ num++;
+ }
+ while (*num && isdigit(*num))
+ value = value * 10 + *num++ - '0';
+ }
+
+ if (neg)
+ value = -value;
+
+ return value;
+}
+
+unsigned long atoul(const char *num)
+{
+ unsigned long value = 0;
+ if (num[0] == '0' && num[1] == 'x') {
+ // hex
+ num += 2;
+ while (*num && isxdigit(*num))
+ value = value * 16 + hexval(*num++);
+ } else {
+ // decimal
+ while (*num && isdigit(*num))
+ value = value * 10 + *num++ - '0';
+ }
+
+ return value;
+}
+