[doc] bits.c: Better / more Doxygen documentation
Change-Id: If824a5c8d8ee6e3dc96a3fddeb105786c0c027c1
diff --git a/src/bits.c b/src/bits.c
index af09441..fa917b0 100644
--- a/src/bits.c
+++ b/src/bits.c
@@ -28,6 +28,11 @@
* @{
* Osmocom bit level support code.
*
+ * This module implements the notion of different bit-fields, such as
+ * - unpacked bits (\ref ubit_t), i.e. 1 bit per byte
+ * - packed bits (\ref pbit_t), i.e. 8 bits per byte
+ * - soft bits (\ref sbit_t), 1 bit per byte from -127 to 127
+ *
* \file bits.c */
/*! convert unpacked bits to packed bits, return length in bytes