1 files changed, 75 insertions, 0 deletions
diff --git a/klibc/klibc/strntoumax.c b/klibc/klibc/strntoumax.c
new file mode 100644
index 0000000000..4e30637d2c
--- /dev/null
+++ b/klibc/klibc/strntoumax.c
@@ -0,0 +1,75 @@
+/*
+ * strntoumax.c
+ *
+ * The strntoumax() function and associated
+ */
+
+#include <stddef.h>
+#include <stdint.h>
+#include <ctype.h>
+
+static inline int digitval(int ch)
+{
+  if ( ch >= '0' && ch <= '9' ) {
+    return ch-'0';
+  } else if ( ch >= 'A' && ch <= 'Z' ) {
+    return ch-'A'+10;
+  } else if ( ch >= 'a' && ch <= 'z' ) {
+    return ch-'a'+10;
+  } else {
+    return -1;
+  }
+}
+
+uintmax_t strntoumax(const char *nptr, char **endptr, int base, size_t n)
+{
+  int minus = 0;
+  uintmax_t v = 0;
+  int d;
+
+  while ( n && isspace((unsigned char)*nptr) ) {
+    nptr++;
+    n--;
+  }
+
+  /* Single optional + or - */
+  if ( n && *nptr == '-' ) {
+    minus = 1;
+    nptr++;
+    n--;
+  } else if ( n && *nptr == '+' ) {
+    nptr++;
+  }
+
+  if ( base == 0 ) {
+    if ( n >= 2 && nptr[0] == '0' &&
+	 (nptr[1] == 'x' || nptr[1] == 'X') ) {
+      n -= 2;
+      nptr += 2;
+      base = 16;
+    } else if ( n >= 1 && nptr[0] == '0' ) {
+      n--;
+      nptr++;
+      base = 8;
+    } else {
+      base = 10;
+    }
+  } else if ( base == 16 ) {
+    if ( n >= 2 && nptr[0] == '0' &&
+	 (nptr[1] == 'x' || nptr[1] == 'X') ) {
+      n -= 2;
+      nptr += 2;
+    }
+  }
+
+  while ( n && (d = digitval(*nptr)) >= 0 && d < base ) {
+    v = v*base + d;
+    n--;
+    nptr++;
+  }
+
+  if ( endptr )
+    *endptr = (char *)nptr;
+
+  return minus ? -v : v;
+}