altos: Compute "real" RSSI value in radio code as needed

Instead of dragging around the weird CC1111 RSSI values, just compute
a dBm value in a signed 8-bit integer, ao_radio_rssi. Use that
everywhere we need RSSI internally. We leave the weird CC1111 value in
the packet reply as that's what the host expects.

Signed-off-by: Keith Packard <keithp@keithp.com>

7 files changed, 43 insertions, 13 deletions

diff --git a/src/cc1111/ao_radio.c b/src/cc1111/ao_radio.c
index 07b0d1b5..4842486b 100644
--- a/src/cc1111/ao_radio.c
+++ b/src/cc1111/ao_radio.c
@@ -249,6 +249,18 @@ __xdata uint8_t ao_radio_done;
 __xdata uint8_t ao_radio_abort;
 __xdata uint8_t ao_radio_mutex;
 
+#if PACKET_HAS_MASTER || HAS_AES
+#define NEED_RADIO_RSSI 1
+#endif
+
+#ifndef NEED_RADIO_RSSI
+#define NEED_RADIO_RSSI 0
+#endif
+
+#if NEED_RADIO_RSSI
+__xdata int8_t ao_radio_rssi;
+#endif
+
 void
 ao_radio_general_isr(void) __interrupt 16
 {
@@ -356,7 +368,14 @@ ao_radio_recv(__xdata void *packet, uint8_t size, uint8_t timeout) __reentrant
 	if (!ao_radio_dma_done) {
 		ao_dma_abort(ao_radio_dma);
 		ao_radio_idle();
+#if NEED_RADIO_RSSI
+		ao_radio_rssi = 0;
+#endif
 	}
+#if NEED_RADIO_RSSI
+	else
+		ao_radio_rssi = AO_RSSI_FROM_RADIO(((uint8_t *)packet)[size - 1]);
+#endif
 	ao_radio_put();
 	return ao_radio_dma_done;
 }
diff --git a/src/core/ao.h b/src/core/ao.h
index 2a8eb042..6bcb3664 100644
--- a/src/core/ao.h
+++ b/src/core/ao.h
@@ -511,6 +511,8 @@ ao_telemetry_tiny_init(void);
 
 extern __xdata uint8_t	ao_radio_dma;
 
+extern __xdata int8_t	ao_radio_rssi;
+
 #ifdef PKT_APPEND_STATUS_1_CRC_OK
 #define AO_RADIO_STATUS_CRC_OK	PKT_APPEND_STATUS_1_CRC_OK
 #else
diff --git a/src/core/ao_packet.h b/src/core/ao_packet.h
index 6d121bb9..b8426cf9 100644
--- a/src/core/ao_packet.h
+++ b/src/core/ao_packet.h
@@ -68,7 +68,7 @@ _ao_packet_pollchar(void);
 #if PACKET_HAS_MASTER
 /* ao_packet_master.c */
 
-extern __xdata uint8_t ao_packet_last_rssi;
+extern __xdata int8_t ao_packet_last_rssi;
 
 void
 ao_packet_master_init(void);
diff --git a/src/core/ao_radio_cmac.c b/src/core/ao_radio_cmac.c
index 4920b50c..3ca3c313 100644
--- a/src/core/ao_radio_cmac.c
+++ b/src/core/ao_radio_cmac.c
@@ -92,7 +92,7 @@ radio_cmac_recv(uint8_t len, uint16_t timeout) __reentrant
 		return AO_RADIO_CMAC_TIMEOUT;
 	}
 
-	ao_radio_cmac_rssi = (int8_t) (((int8_t) cmac_data[len + AO_CMAC_KEY_LEN]) >> 1) - 74;
+	ao_radio_cmac_rssi = ao_radio_rssi;
 	if (!(cmac_data[len + AO_CMAC_KEY_LEN +1] & AO_RADIO_STATUS_CRC_OK))
 		return AO_RADIO_CMAC_CRC_ERROR;
 
@@ -146,7 +146,7 @@ ao_radio_cmac_send(__xdata void *packet, uint8_t len) __reentrant
 int8_t
 ao_radio_cmac_recv(__xdata void *packet, uint8_t len, uint16_t timeout) __reentrant
 {
-	uint8_t	i;
+	int8_t	i;
 	if (len > AO_CMAC_MAX_LEN)
 		return AO_RADIO_CMAC_LEN_ERROR;
 	ao_mutex_get(&ao_radio_cmac_mutex);
diff --git a/src/drivers/ao_cc1120.c b/src/drivers/ao_cc1120.c
index 07ebf835..b6b77a5a 100644
--- a/src/drivers/ao_cc1120.c
+++ b/src/drivers/ao_cc1120.c
@@ -32,6 +32,8 @@ static uint8_t ao_radio_mcu_wake;	/* MARC status change */
 static uint8_t ao_radio_marc_status;	/* Last read MARC status value */
 static uint8_t ao_radio_tx_finished;	/* MARC status indicates TX finished */
 
+int8_t	ao_radio_rssi;			/* Last received RSSI value */
+
 #define CC1120_DEBUG	AO_FEC_DEBUG
 #define CC1120_TRACE	0
 
@@ -552,6 +554,7 @@ ao_radio_get(uint8_t len)
 	static uint32_t	last_radio_setting;
 
 	ao_mutex_get(&ao_radio_mutex);
+
 	if (!ao_radio_configured)
 		ao_radio_setup();
 	if (ao_config.radio_setting != last_radio_setting) {
@@ -909,7 +912,8 @@ ao_radio_recv(__xdata void *d, uint8_t size, uint8_t timeout)
 {
 	uint8_t		len;
 	uint16_t	i;
-	uint8_t		rssi;
+	uint8_t		radio_rssi = 0;
+	uint8_t		rssi0;
 	uint8_t		ret;
 	static int been_here = 0;
 
@@ -977,17 +981,26 @@ ao_radio_recv(__xdata void *d, uint8_t size, uint8_t timeout)
 	ao_radio_burst_read_stop();
 
 abort:
-	ao_radio_strobe(CC1120_SIDLE);
-
 	/* Convert from 'real' rssi to cc1111-style values */
 
-	rssi = AO_RADIO_FROM_RSSI(ao_radio_reg_read(CC1120_RSSI1));
+	rssi0 = ao_radio_reg_read(CC1120_RSSI0);
+	if (rssi0 & 1) {
+		int8_t rssi = ao_radio_reg_read(CC1120_RSSI1);
+		ao_radio_rssi = rssi;
+
+		/* Bound it to the representable range */
+		if (rssi > -11)
+			rssi = -11;
+		radio_rssi = AO_RADIO_FROM_RSSI (rssi);
+	}
+
+	ao_radio_strobe(CC1120_SIDLE);
 
 	ao_radio_put();
 
 	/* Store the received RSSI value; the crc-OK byte is already done */
 
-	((uint8_t *) d)[size] = (uint8_t) rssi;
+	((uint8_t *) d)[size] = radio_rssi;
 
 #if AO_PROFILE
 	rx_last_done_tick = rx_done_tick;
diff --git a/src/drivers/ao_packet.c b/src/drivers/ao_packet.c
index 802d4c90..8cdf85a9 100644
--- a/src/drivers/ao_packet.c
+++ b/src/drivers/ao_packet.c
@@ -31,7 +31,6 @@ __xdata uint8_t ao_packet_restart;
 
 #if PACKET_HAS_MASTER
 __xdata uint8_t ao_packet_master_sleeping;
-__xdata uint8_t ao_packet_last_rssi;
 #endif
 
 void
@@ -85,9 +84,6 @@ ao_packet_recv(void)
 	if (!(ao_rx_packet.status & AO_RADIO_STATUS_CRC_OK))
 		return 0;
 
-#if PACKET_HAS_MASTER
-	ao_packet_last_rssi = ao_rx_packet.rssi;
-#endif
 	/* Accept packets with matching call signs, or any packet if
 	 * our callsign hasn't been configured
 	 */
diff --git a/src/drivers/ao_packet_master.c b/src/drivers/ao_packet_master.c
index 4c0dc573..d6c99cbd 100644
--- a/src/drivers/ao_packet_master.c
+++ b/src/drivers/ao_packet_master.c
@@ -145,7 +145,7 @@ ao_packet_forward(void) __reentrant
 static void
 ao_packet_signal(void)
 {
-	printf ("RSSI: %d\n", AO_RSSI_FROM_RADIO(ao_packet_last_rssi));
+	printf ("RSSI: %d\n", ao_radio_rssi);
 }
 
 __code struct ao_cmds ao_packet_master_cmds[] = {