From: Keith Packard <keithp@keithp.com>
Date: Mon, 25 Jun 2012 13:38:34 +0000 (-0700)
Subject: altos: decode cc1120 received packets
X-Git-Tag: 1.0.9.6~37
X-Git-Url: https://git.gag.com/?p=fw%2Faltos;a=commitdiff_plain;h=628076aa90e7bc9a894646e417dd8e1fe149b60d

altos: decode cc1120 received packets

Call the fec decode function, compute RSSI and check CRC

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

diff --git a/src/core/ao_fec.h b/src/core/ao_fec.h
index f3f55fa8..e3c55d6e 100644
--- a/src/core/ao_fec.h
+++ b/src/core/ao_fec.h
@@ -67,7 +67,7 @@ ao_fec_encode(uint8_t *in, uint8_t len, uint8_t *out);
  */
 
 uint8_t
-ao_fec_decode(uint8_t *in, uint16_t in_len, uint8_t *out);
+ao_fec_decode(uint8_t *in, uint16_t in_len, uint8_t *out, uint8_t out_len);
 
 /*
  * Interleave data packed in bytes. 'out' must be 'len' bytes long.
diff --git a/src/core/ao_viterbi.c b/src/core/ao_viterbi.c
index 594c0d91..77681556 100644
--- a/src/core/ao_viterbi.c
+++ b/src/core/ao_viterbi.c
@@ -91,7 +91,7 @@ ao_cost(struct ao_soft_sym a, struct ao_soft_sym b)
  */
 
 uint8_t
-ao_fec_decode(uint8_t *in, uint16_t len, uint8_t *out)
+ao_fec_decode(uint8_t *in, uint16_t len, uint8_t *out, uint8_t out_len)
 {
 	static uint16_t	cost[2][NUM_STATE];		/* path cost */
 	static uint16_t	bits[2][NUM_STATE];		/* save bits to quickly output them */
@@ -203,7 +203,10 @@ ao_fec_decode(uint8_t *in, uint16_t len, uint8_t *out)
 			printf ("\tbit %3d min_cost %5d old bit %3d old_state %x bits %02x whiten %0x\n",
 				i/2, min_cost, o + 8, min_state, (bits[p][min_state] >> dist) & 0xff, *whiten);
 #endif
-			*out++ = (bits[p][min_state] >> dist) ^ *whiten++;
+			if (out_len) {
+				*out++ = (bits[p][min_state] >> dist) ^ *whiten++;
+				--out_len;
+			}
 			o += 8;
 		}
 	}
diff --git a/src/drivers/ao_cc1120.c b/src/drivers/ao_cc1120.c
index 4378716d..b42ca54c 100644
--- a/src/drivers/ao_cc1120.c
+++ b/src/drivers/ao_cc1120.c
@@ -401,12 +401,12 @@ ao_radio_send(void *d, uint8_t size)
 static uint8_t	rx_data[2048];
 static uint16_t	rx_data_count;
 static uint16_t rx_data_cur;
-static uint8_t	rx_started;
+static uint8_t	rx_ignore;
 
 static void
 ao_radio_rx_isr(void)
 {
-	if (rx_started) {
+	if (rx_ignore == 0) {
 		rx_data[rx_data_cur++] = stm_spi2.dr;
 		if (rx_data_cur >= rx_data_count) {
 			ao_exti_disable(&AO_CC1120_INT_PORT, AO_CC1120_INT_PIN);
@@ -415,7 +415,7 @@ ao_radio_rx_isr(void)
 		}
 	} else {
 		(void) stm_spi2.dr;
-		rx_started = 1;
+		--rx_ignore;
 	}
 	stm_spi2.dr = 0x00;
 }
@@ -423,12 +423,17 @@ ao_radio_rx_isr(void)
 uint8_t
 ao_radio_recv(__xdata void *d, uint8_t size)
 {
-	uint8_t		len = ((size - 2) + 4) * 2;	/* two bytes for status */
+	uint8_t		len;
 	uint16_t	i;
+	uint8_t		rssi;
 
-	rx_data_count = sizeof (rx_data);
+	size -= 2;			/* status bytes */
+	len = size + 2;			/* CRC bytes */
+	len += 1 + ~(len & 1);		/* 1 or two pad bytes */
+	len *= 2;			/* 1/2 rate convolution */
+	rx_data_count = len * 8;	/* bytes to bits */
 	rx_data_cur = 0;
-	rx_started = 0;
+	rx_ignore = 2;
 
 	printf ("len %d rx_data_count %d\n", len, rx_data_count);
 
@@ -456,31 +461,31 @@ ao_radio_recv(__xdata void *d, uint8_t size)
 	ao_radio_strobe(CC1120_SRX);
 
 	ao_radio_burst_read_start(CC1120_SOFT_RX_DATA_OUT);
-#if 1
 	cli();
 	while (!ao_radio_wake && !ao_radio_abort)
 		ao_sleep(&ao_radio_wake);
 	sei();
-
-#else
-	printf ("Hit a character to stop..."); flush();
-	getchar();
-	putchar('\n');
-	ao_exti_disable(&AO_CC1120_INT_PORT, AO_CC1120_INT_PIN);
-#endif
 	ao_radio_burst_read_stop();
 
+	/* Convert from 'real' rssi to cc1111-style values */
+
+	rssi = (((int8_t) ao_radio_reg_read(CC1120_RSSI1)) + 74) * 2;
+
 	ao_radio_strobe(CC1120_SIDLE);
 
 	ao_radio_put();
 
-	printf ("Received data:");
-	for (i = 0; i < rx_data_cur; i++) {
-		if ((i & 15) == 0)
-			printf ("\n");
-		printf (" %02x", rx_data[i]);
-	}
-	printf ("\n");
+	/* Construct final packet */
+
+	ao_fec_decode(rx_data, rx_data_cur, d, size + 2);
+
+	if (ao_fec_check_crc(d, size))
+		((uint8_t *) d)[size + 1] = 0x80;
+	else
+		((uint8_t *) d)[size + 1] = 0x00;
+
+	((uint8_t *) d)[size] = (uint8_t) rssi;
+
 	return 1;
 }