Move decode_hex into its own file

- Error detection against strotul(3) has been improved, as done in other
places.
- New function encode_hex has been implemented, which will be used
by future commits.

1 files changed, 9 insertions, 0 deletions

diff --git a/hex.h b/hex.h
new file mode 100644
index 0000000..2195415
--- /dev/null
+++ b/hex.h
@@ -0,0 +1,9 @@
+#ifndef HEX_H
+#define HEX_H
+
+#include <stddef.h>
+
+int hex_encode(const void *buf, char *hex, size_t buflen, size_t hexlen);
+int hex_decode(const char *hex, void *buf, size_t n);
+
+#endif /* HEX_H */