166 lines
4.3 KiB
C
166 lines
4.3 KiB
C
/*
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* ubx-parse.c
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*
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* Implementation of parsing code converting UBX messages to GPS assist
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* data
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*
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*
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* Copyright (C) 2009 Sylvain Munaut <tnt@246tNt.com>
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <stdio.h>
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#include "gps.h"
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#include "ubx.h"
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#include "ubx-parse.h"
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/* Helpers */
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static int
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float_to_fixedpoint(float f, int sf)
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{
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if (sf < 0) {
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while (sf++ < 0)
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f *= 2.0f;
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} else {
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while (sf-- > 0)
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f *= 0.5f;
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}
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return (int)f;
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}
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static inline int
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double_to_fixedpoint(double d, int sf)
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{
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if (sf < 0) {
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while (sf++ < 0)
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d *= 2.0;
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} else {
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while (sf-- > 0)
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d *= 0.5;
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}
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return (int)d;
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}
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/* UBX message parsing to fill gps assist data */
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static void
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_ubx_msg_parse_nav_posllh(struct ubx_hdr *hdr, void *pl, int pl_len, void *ud)
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{
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struct ubx_nav_posllh *nav_posllh = pl;
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struct gps_assist_data *gps = ud;
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//printf("[.] NAV_POSLLH\n");
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// FIXME: Extract info for "Reference Position"
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}
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static void
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_ubx_msg_parse_aid_ini(struct ubx_hdr *hdr, void *pl, int pl_len, void *ud)
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{
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struct ubx_aid_ini *aid_ini = pl;
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struct gps_assist_data *gps = ud;
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//printf("[.] AID_INI\n");
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// FIXME: Extract info for "Reference Time"
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}
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static void
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_ubx_msg_parse_aid_hui(struct ubx_hdr *hdr, void *pl, int pl_len, void *ud)
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{
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struct ubx_aid_hui *aid_hui = pl;
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struct gps_assist_data *gps = ud;
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//printf("[.] AID_HUI\n");
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if (aid_hui->flags & 0x2) { /* UTC parameters valid */
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struct gps_utc_model *utc = &gps->utc;
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gps->fields |= GPS_FIELD_UTC;
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utc->a0 = double_to_fixedpoint(aid_hui->utc_a0, -30);
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utc->a1 = double_to_fixedpoint(aid_hui->utc_a1, -50);
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utc->delta_t_ls = aid_hui->utc_ls;
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utc->t_ot = aid_hui->utc_tot >> 12;
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utc->wn_t = aid_hui->utc_wnt;
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utc->wn_lsf = aid_hui->utc_wnf;
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utc->dn = aid_hui->utc_dn;
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utc->delta_t_lsf = aid_hui->utc_lsf;
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}
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if (aid_hui->flags & 0x04) { /* Klobuchar parameters valid */
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struct gps_ionosphere_model *iono = &gps->ionosphere;
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gps->fields |= GPS_FIELD_IONOSPHERE;
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iono->alpha_0 = float_to_fixedpoint(aid_hui->klob_a0, -30);
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iono->alpha_1 = float_to_fixedpoint(aid_hui->klob_a1, -27);
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iono->alpha_2 = float_to_fixedpoint(aid_hui->klob_a2, -24);
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iono->alpha_3 = float_to_fixedpoint(aid_hui->klob_a3, -24);
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iono->beta_0 = float_to_fixedpoint(aid_hui->klob_b0, 11);
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iono->beta_1 = float_to_fixedpoint(aid_hui->klob_b1, 14);
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iono->beta_2 = float_to_fixedpoint(aid_hui->klob_b2, 16);
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iono->beta_3 = float_to_fixedpoint(aid_hui->klob_b3, 16);
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}
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}
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static void
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_ubx_msg_parse_aid_alm(struct ubx_hdr *hdr, void *pl, int pl_len, void *ud)
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{
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struct ubx_aid_alm *aid_alm = pl;
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struct gps_assist_data *gps = ud;
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//printf("[.] AID_ALM %d - %d\n", aid_alm->sv_id, aid_alm->gps_week);
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if (aid_alm->gps_week) {
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gps->fields |= GPS_FIELD_ALMANAC;
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gps->almanac.wna = aid_alm->gps_week & 0xff;
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gps_unpack_sf45_almanac(aid_alm->alm_words, &gps->almanac.svs[gps->almanac.n_sv++]);
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}
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}
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static void
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_ubx_msg_parse_aid_eph(struct ubx_hdr *hdr, void *pl, int pl_len, void *ud)
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{
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struct ubx_aid_eph *aid_eph = pl;
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struct gps_assist_data *gps = ud;
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//printf("[.] AID_EPH %d - %s\n", aid_eph->sv_id, aid_eph->present ? "present" : "not present");
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if (aid_eph->present) {
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int i = gps->ephemeris.n_sv++;
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gps->fields |= GPS_FIELD_EPHEMERIS;
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gps->ephemeris.svs[i].sv_id = aid_eph->sv_id;
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gps_unpack_sf123(aid_eph->eph_words, &gps->ephemeris.svs[i]);
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}
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}
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/* Dispatch table */
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struct ubx_dispatch_entry ubx_parse_dt[] = {
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UBX_DISPATCH(NAV, POSLLH, _ubx_msg_parse_nav_posllh),
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UBX_DISPATCH(AID, INI, _ubx_msg_parse_aid_ini),
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UBX_DISPATCH(AID, HUI, _ubx_msg_parse_aid_hui),
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UBX_DISPATCH(AID, ALM, _ubx_msg_parse_aid_alm),
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UBX_DISPATCH(AID, EPH, _ubx_msg_parse_aid_eph),
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};
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