trx/scheduler: Use integer math for TOA (Timing of Arrival)

There's no need to express TOA as a float:
* We receive it as signed 16bit integer in units 1/256 symbol periods
* We pass it to L1SAP as signed integer in 1/4 symbol periods

So turn it into an int16_t with 1/256 symbol period accuracy throughout
the code to avoid both float arithmetic as well as loosing any precision.

Change-Id: Idce4178e0b1f7e940ebc22b3e2f340fcd544d4ec

2 files changed, 9 insertions, 9 deletions

diff --git a/include/osmo-bts/scheduler.h b/include/osmo-bts/scheduler.h
index 4d34315f..98f38d39 100644
--- a/include/osmo-bts/scheduler.h
+++ b/include/osmo-bts/scheduler.h
@@ -75,7 +75,7 @@ struct l1sched_chan_state {
 	uint8_t			rssi_num;	/* number of RSSI values */
 	float			rssi_sum;	/* sum of RSSI values */
 	uint8_t			toa_num;	/* number of TOA values */
-	float			toa_sum;	/* sum of TOA values */
+	int32_t			toa256_sum;	/* sum of TOA values (1/256 symbol) */
 
 	/* loss detection */
 	uint8_t			lost;		/* (SACCH) loss detection */
@@ -113,7 +113,7 @@ struct l1sched_chan_state {
 		int		rssi_count;	/* received RSSI values */
 		int		rssi_valid_count; /* number of stored value */
 		int		rssi_got_burst; /* any burst received so far */
-		float		toa_sum;	/* sum of TOA values */
+		int32_t		toa256_sum;	/* sum of TOA values (1/256 symbol) */
 		int		toa_num;	/* number of TOA value */
 	} meas;
 
@@ -165,7 +165,7 @@ int trx_sched_clock(struct gsm_bts *bts, uint32_t fn);
 
 /*! \brief handle an UL burst received by PHY */
 int trx_sched_ul_burst(struct l1sched_trx *l1t, uint8_t tn, uint32_t fn,
-        sbit_t *bits, uint16_t nbits, int8_t rssi, float toa);
+        sbit_t *bits, uint16_t nbits, int8_t rssi, int16_t toa);
 
 /*! \brief set multiframe scheduler to given physical channel config */
 int trx_sched_set_pchan(struct l1sched_trx *l1t, uint8_t tn,
diff --git a/include/osmo-bts/scheduler_backend.h b/include/osmo-bts/scheduler_backend.h
index 5e077eff..5f11f9bc 100644
--- a/include/osmo-bts/scheduler_backend.h
+++ b/include/osmo-bts/scheduler_backend.h
@@ -16,7 +16,7 @@ typedef ubit_t *trx_sched_dl_func(struct l1sched_trx *l1t, uint8_t tn,
 typedef int trx_sched_ul_func(struct l1sched_trx *l1t, uint8_t tn,
 			      uint32_t fn, enum trx_chan_type chan,
 			      uint8_t bid, sbit_t *bits, uint16_t nbits,
-			      int8_t rssi, float toa);
+			      int8_t rssi, int16_t toa256);
 
 struct trx_chan_desc {
 	/*! \brief Is this on a PDCH (PS) ? */
@@ -74,19 +74,19 @@ ubit_t *tx_tchh_fn(struct l1sched_trx *l1t, uint8_t tn, uint32_t fn,
 	enum trx_chan_type chan, uint8_t bid, uint16_t *nbits);
 int rx_rach_fn(struct l1sched_trx *l1t, uint8_t tn, uint32_t fn,
 	enum trx_chan_type chan, uint8_t bid, sbit_t *bits, uint16_t nbits,
-	int8_t rssi, float toa);
+	int8_t rssi, int16_t toa256);
 int rx_data_fn(struct l1sched_trx *l1t, uint8_t tn, uint32_t fn,
 	enum trx_chan_type chan, uint8_t bid, sbit_t *bits, uint16_t nbits,
-	int8_t rssi, float toa);
+	int8_t rssi, int16_t toa256);
 int rx_pdtch_fn(struct l1sched_trx *l1t, uint8_t tn, uint32_t fn,
 	enum trx_chan_type chan, uint8_t bid, sbit_t *bits, uint16_t nbits,
-	int8_t rssi, float toa);
+	int8_t rssi, int16_t toa256);
 int rx_tchf_fn(struct l1sched_trx *l1t, uint8_t tn, uint32_t fn,
 	enum trx_chan_type chan, uint8_t bid, sbit_t *bits, uint16_t nbits,
-	int8_t rssi, float toa);
+	int8_t rssi, int16_t toa256);
 int rx_tchh_fn(struct l1sched_trx *l1t, uint8_t tn, uint32_t fn,
 	enum trx_chan_type chan, uint8_t bid, sbit_t *bits, uint16_t nbits,
-	int8_t rssi, float toa);
+	int8_t rssi, int16_t toa256);
 
 const ubit_t *_sched_dl_burst(struct l1sched_trx *l1t, uint8_t tn,
 			      uint32_t fn, uint16_t *nbits);