feature (libnx): implemented basic string utils

libnx/inc/public/nox/string.h

@@ -8,5 +8,10 @@
 typedef const char* string_t;
 
 uint64_t strlen     (string_t str);
+uint64_t str2int    (string_t str, uint32_t base, uint64_t* len);
+
+bool     is_numeric (char chr);
+bool     is_lower   (char chr);
+bool     is_upper   (char chr);
 
 #endif //LIBNX_STRING_H

libnx/src/string.c

@@ -7,3 +7,36 @@ uint64_t strlen(string_t str) {
     while (str[n++]);
     return n;
 }
+
+uint64_t str2int(string_t str, uint32_t base, uint64_t* len) {
+    uint64_t num = 0;
+
+    while (is_numeric(*str)) {
+        num *= base;
+        num += *str - '0';
+
+        str++;
+        if (len != NULL) *len += 1;
+    }
+
+    return num;
+}
+
+bool is_numeric(char chr) {
+    return (chr >= '0' && chr <= '9');
+}
+
+bool is_lower(char chr) {
+    return (chr >= 'a' && chr <= 'z');
+}
+
+bool is_upper(char chr) {
+    return (chr >= 'A' && chr <= 'Z');
+}
+
+bool is_special(char chr) {
+    return ((chr >= '!' && chr <= '/') ||
+            (chr >= ':' && chr <= '@') ||
+            (chr >= '[' && chr <= '`') ||
+            (chr >= '{' && chr <= '~'));
+}