diff options
Diffstat (limited to 'isgps.c')
| -rw-r--r-- | isgps.c | 32 |
1 files changed, 32 insertions, 0 deletions
@@ -305,3 +305,35 @@ enum isgpsstat_t isgps_decode(struct gps_packet_t *session, return ISGPS_NO_SYNC; } /*@ +usereleased +compdef @*/ + +/* + * ISGPS data words are 30-bit words. We will lay them into memory into + * 30-bit (low-end justified) chunks. To write them out we will write + * 5 Magnavox-format bytes where the low 6-bits of the byte are 6-bits + * of the 30-word msg. + */ +void isgps_output_magnavox(isgps30bits_t *ip, unsigned int len, FILE *fp) +/* ship an RTCM message to standard output in Magnavox format */ +{ + static isgps30bits_t w = 0; + + while (len-- > 0) { + w <<= 30; + w |= *ip++ & W_DATA_MASK; + + w |= isgps_parity(w); + + /* weird-assed inversion */ + if (w & P_30_MASK) + w ^= W_DATA_MASK; + + /* msb first */ + /*@ -type @*/ + (void)fputc(MAG_TAG_DATA | reverse_bits[(w >> 24) & 0x3f], fp); + (void)fputc(MAG_TAG_DATA | reverse_bits[(w >> 18) & 0x3f], fp); + (void)fputc(MAG_TAG_DATA | reverse_bits[(w >> 12) & 0x3f], fp); + (void)fputc(MAG_TAG_DATA | reverse_bits[(w >> 6) & 0x3f], fp); + (void)fputc(MAG_TAG_DATA | reverse_bits[(w) & 0x3f], fp); + /*@ +type @*/ + } +} |