Clarify write_immediate_assignment() signature

* remove unused variable
* use bool for boolean types
* add clarification comments

Change-Id: I363445063e2d873d9194b2a5924b9e59b8b7ea53
diff --git a/src/encoding.cpp b/src/encoding.cpp
index 0241b39..2c89819 100644
--- a/src/encoding.cpp
+++ b/src/encoding.cpp
@@ -90,7 +90,7 @@
 static int write_ia_rest_downlink(
 	gprs_rlcmac_dl_tbf *tbf,
 	bitvec * dest, unsigned& wp,
-	uint8_t polling, bool ta_valid, uint32_t fn,
+	bool polling, bool ta_valid, uint32_t fn,
 	uint8_t alpha, uint8_t gamma, int8_t ta_idx)
 {
 	if (!tbf) {
@@ -342,10 +342,10 @@
  */
 int Encoding::write_immediate_assignment(
 	struct gprs_rlcmac_tbf *tbf,
-	bitvec * dest, uint8_t downlink, uint16_t ra,
+	bitvec * dest, bool downlink, uint16_t ra,
 	uint32_t ref_fn, uint8_t ta, uint16_t arfcn, uint8_t ts, uint8_t tsc,
-	uint8_t usf, uint8_t polling, uint32_t fn, uint8_t alpha,
-	uint8_t gamma, int8_t ta_idx, enum ph_burst_type burst_type, uint8_t sb)
+	uint8_t usf, bool polling, uint32_t fn, uint8_t alpha,
+	uint8_t gamma, int8_t ta_idx, enum ph_burst_type burst_type)
 {
 	unsigned wp = 0;
 	int plen;