1 files changed, 45 insertions, 0 deletions

diff --git a/firmware/libc/strcspn.c b/firmware/libc/strcspn.c
new file mode 100644
index 0000000000..ee50066ed1
--- /dev/null
+++ b/firmware/libc/strcspn.c
@@ -0,0 +1,45 @@
+/*
+FUNCTION
+        <<strcspn>>---count characters not in string
+INDEX
+        strcspn
+ANSI_SYNOPSIS
+        size_t strcspn(const char *<[s1]>, const char *<[s2]>);
+TRAD_SYNOPSIS
+        size_t strcspn(<[s1]>, <[s2]>)
+        char *<[s1]>;
+        char *<[s2]>;
+DESCRIPTION
+        This function computes the length of the initial part of
+        the string pointed to by <[s1]> which consists entirely of
+        characters <[NOT]> from the string pointed to by <[s2]>
+        (excluding the terminating null character).
+RETURNS
+        <<strcspn>> returns the length of the substring found.
+PORTABILITY
+<<strcspn>> is ANSI C.
+<<strcspn>> requires no supporting OS subroutines.
+ */
+#include <string.h>
+#include "_ansi.h" /* for _DEFUN */
+
+size_t
+_DEFUN (strcspn, (s1, s2),
+        _CONST char *s1 _AND
+        _CONST char *s2)
+{
+  _CONST char *s = s1;
+  _CONST char *c;
+  while (*s1)
+    {
+        for (c = s2; *c; c++)
+        {
+            if (*s1 == *c)
+                break;
+        }
+        if (*c)
+            break;
+        s1++;
+    }
+    return s1 - s;
+}