Parse Skytraq packets to inbuffer.

No packet decoder yet.

gpsd.h-tail

@@ -149,6 +149,7 @@ struct gps_lexer_t {
 #define RTCM3_PACKET    	17
 #define JSON_PACKET    	    	18
 #define PACKET_TYPES		19	/* increment this as necessary */
+#define SKY_PACKET     		20
 #define TEXTUAL_PACKET_TYPE(n)	((((n)>=NMEA_PACKET) && ((n)<=MAX_TEXTUAL_TYPE)) || (n)==JSON_PACKET)
 #define GPS_PACKET_TYPE(n)	(((n)>=NMEA_PACKET) && ((n)<=MAX_GPSPACKET_TYPE))
 #define LOSSLESS_PACKET_TYPE(n)	(((n)>=RTCM2_PACKET) && ((n)<=RTCM3_PACKET))

packet.c

@@ -250,12 +250,12 @@ static bool nextstate(struct gps_lexer_t *lexer, unsigned char c)
 	    break;
 	}
 #endif
-#ifdef SIRF_ENABLE
+#if defined(SIRF_ENABLE) || defined(SKYTRAQ_ENABLE)
 	if (c == 0xa0) {
 	    lexer->state = SIRF_LEADER_1;
 	    break;
 	}
-#endif /* SIRF_ENABLE */
+#endif /* SIRF_ENABLE || SKYTRAQ_ENABLE */
 #ifdef SUPERSTAR2_ENABLE
 	if (c == SOH) {
 	    lexer->state = SUPERSTAR2_LEADER;
@@ -796,13 +796,24 @@ static bool nextstate(struct gps_lexer_t *lexer, unsigned char c)
 	    return character_pushback(lexer, GROUND_STATE);
 	break;
 #endif /* NMEA0183_ENABLE */
-#ifdef SIRF_ENABLE
+#if defined(SIRF_ENABLE) || defined(SKYTRAQ_ENABLE)
     case SIRF_LEADER_1:
+# ifdef SIRF_ENABLE
+        /* SIRF leads with 0xA0,0xA2 */
 	if (c == 0xa2)
 	    lexer->state = SIRF_LEADER_2;
 	else
+# endif /* SIRF_ENABLE */
+# ifdef SKYTRAQ_ENABLE
+        /* Skytraq leads with 0xA0,0xA1 */
+	if (c == 0xa1)
+	    lexer->state = SKY_LEADER_2;
+	else
+# endif /* SKYTRAQ_ENABLE */
 	    return character_pushback(lexer, GROUND_STATE);
 	break;
+#endif /* SIRF_ENABLE || SKYTRAQ_ENABLE */
+#ifdef SIRF_ENABLE
     case SIRF_LEADER_2:
 	lexer->length = (size_t) (c << 8);
 	lexer->state = SIRF_LENGTH_1;
@@ -837,6 +848,66 @@ static bool nextstate(struct gps_lexer_t *lexer, unsigned char c)
 	    return character_pushback(lexer, GROUND_STATE);
 	break;
 #endif /* SIRF_ENABLE */
+#ifdef SKYTRAQ_ENABLE
+    case SKY_LEADER_2:
+        /* MSB of length is first */
+	lexer->length = (size_t) (c << 8);
+	lexer->state = SKY_LENGTH_1;
+	break;
+    case SKY_LENGTH_1:
+        /* Skytraq length can be any 16 bit number, except 0 */
+	lexer->length += c;
+	if ( 0 == lexer->length )
+	    return character_pushback(lexer, GROUND_STATE);
+	if (lexer->length > MAX_PACKET_LENGTH)
+	    return character_pushback(lexer, GROUND_STATE);
+	lexer->state = SKY_PAYLOAD;
+	break;
+    case SKY_PAYLOAD:
+	if ( 00 == --lexer->length)
+	    lexer->state = SKY_DELIVERED;
+	break;
+    case SKY_DELIVERED:
+	if ( lexer->errout.debug >= LOG_RAW+1) {
+	    char scratchbuf[MAX_PACKET_LENGTH*2+1];
+	    gpsd_log(&lexer->errout, LOG_RAW+1,
+		     "Skytraq = %s\n",
+		     gpsd_packetdump(scratchbuf,  sizeof(scratchbuf),
+			 (char *)lexer->inbuffer,
+			 lexer->inbufptr - (unsigned char *)lexer->inbuffer));
+	}
+	{
+	    unsigned char csum = 0;
+	    for (n = 4;
+		 (unsigned char *)(lexer->inbuffer + n) < lexer->inbufptr - 1;
+		 n++)
+		csum ^= lexer->inbuffer[n];
+	    if (csum != c) {
+		gpsd_log(&lexer->errout, LOG_IO,
+			 "Skytraq bad checksum 0x%hhx, expecting 0x%x\n",
+			 csum, c);
+		lexer->state = GROUND_STATE;
+		break;
+	    }
+	}
+	lexer->state = SKY_CSUM;
+	break;
+    case SKY_CSUM:
+	if ( 0x0d != c)
+	    return character_pushback(lexer, GROUND_STATE);
+	lexer->state = SKY_TRAILER_1;
+	break;
+    case SKY_TRAILER_1:
+	if ( 0x0a != c)
+	    return character_pushback(lexer, GROUND_STATE);
+	lexer->state = SKY_RECOGNIZED;
+	break;
+    case SKY_RECOGNIZED:
+	if ( 0xa0 != c)
+	    return character_pushback(lexer, GROUND_STATE);
+	lexer->state = SIRF_LEADER_1;
+	break;
+#endif /* SKYTRAQ */
 #ifdef SUPERSTAR2_ENABLE
     case SUPERSTAR2_LEADER:
 	ctmp = c;
@@ -1676,6 +1747,13 @@ void packet_parse(struct gps_lexer_t *lexer)
 	    break;
 	}
 #endif /* SIRF_ENABLE */
+#ifdef SKYTRAQ_ENABLE
+	else if (lexer->state == SKY_RECOGNIZED) {
+	    // packet_accept(lexer, SKY_PACKET);
+	    packet_discard(lexer);
+	    break;
+	}
+#endif /* SKYTRAQ_ENABLE */
 #ifdef SUPERSTAR2_ENABLE
 	else if (lexer->state == SUPERSTAR2_RECOGNIZED) {
 	    unsigned a = 0, b;

packet_states.h

@@ -57,8 +57,10 @@
    EARTHA_5,		/* EARTHA leader H */
 #endif /* EARTHMATE_ENABLE */
 
+#if defined(SIRF_ENABLE) || defined(SKYTRAQ_ENABLE)
+   SIRF_LEADER_1,	/* seen first character of SiRF/Skytraq leader <0x0A> */
+#endif /* SIRF_ENABLE || SKYTRAQ_ENABLE */
 #ifdef SIRF_ENABLE
-   SIRF_LEADER_1,	/* we've seen first character of SiRF leader */
    SIRF_LEADER_2,	/* seen second character of SiRF leader */
    SIRF_LENGTH_1,	/* seen first byte of SiRF length */
    SIRF_PAYLOAD,	/* we're in a SiRF payload part */
@@ -69,15 +71,15 @@
 
 #ifdef SKYTRAQ_ENABLE
    /* <0xA0,0xA1><Len><Message ID><Message Body><csum><0x0D,0x0A> */
-   /* Len is of Message ID and Message Body */
-   SKY_EXPECTED,	/* expecting Skytraq packet */
-   SKY_LEADER_1,	/* saw leading 0xA0 */
-   SKY_LEADER_2,	/* saw leading 0xA1 */
+   /* Len is two bytes, is the length of Message ID and Message Body */
+   /* Skytraq leader 1 same as SIRF_LEADER_1 */
+   SKY_LEADER_2,	/* saw leader 2 <0xA1> */
    SKY_LENGTH_1,	/* saw first byte of packet length */
    SKY_LENGTH_2,	/* saw second byte of packet length */
-   SKY_MID,		/* saw message one byte ID */
    SKY_PAYLOAD,		/* we're in a Skytraq payload */
+   SKY_DELIVERED,	/* saw last byte of Skytraq payload */
    SKY_CSUM,		/* saw Skytraq checksum */
+   SKY_TRAILER_1,	/* saw first byte of Skytraq trailer <0x0D> */
    SKY_RECOGNIZED,	/* found end of the Skytraq packet */
 #endif /* SKYTRAQ_ENABLE */