Import code to generate RRLP ephemeris data from u-blox GPS receiver
taken from http://www.246tnt.com/files/rrlp-20091101.tar.bz2
diff --git a/rrlp-ephemeris/ubx-parse.c b/rrlp-ephemeris/ubx-parse.c
new file mode 100644
index 0000000..cb8c22e
--- /dev/null
+++ b/rrlp-ephemeris/ubx-parse.c
@@ -0,0 +1,165 @@
+/*
+ * ubx-parse.c
+ *
+ * Implementation of parsing code converting UBX messages to GPS assist
+ * data
+ *
+ *
+ * Copyright (C) 2009 Sylvain Munaut <tnt@246tNt.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdio.h>
+
+#include "gps.h"
+#include "ubx.h"
+#include "ubx-parse.h"
+
+
+/* Helpers */
+
+static int
+float_to_fixedpoint(float f, int sf)
+{
+ if (sf < 0) {
+ while (sf++ < 0)
+ f *= 2.0f;
+ } else {
+ while (sf-- > 0)
+ f *= 0.5f;
+ }
+
+ return (int)f;
+}
+
+static inline int
+double_to_fixedpoint(double d, int sf)
+{
+ if (sf < 0) {
+ while (sf++ < 0)
+ d *= 2.0;
+ } else {
+ while (sf-- > 0)
+ d *= 0.5;
+ }
+
+ return (int)d;
+}
+
+
+/* UBX message parsing to fill gps assist data */
+
+static void
+_ubx_msg_parse_nav_posllh(struct ubx_hdr *hdr, void *pl, int pl_len, void *ud)
+{
+ struct ubx_nav_posllh *nav_posllh = pl;
+ struct gps_assist_data *gps = ud;
+
+ //printf("[.] NAV_POSLLH\n");
+
+ // FIXME: Extract info for "Reference Position"
+}
+
+static void
+_ubx_msg_parse_aid_ini(struct ubx_hdr *hdr, void *pl, int pl_len, void *ud)
+{
+ struct ubx_aid_ini *aid_ini = pl;
+ struct gps_assist_data *gps = ud;
+
+ //printf("[.] AID_INI\n");
+
+ // FIXME: Extract info for "Reference Time"
+}
+
+static void
+_ubx_msg_parse_aid_hui(struct ubx_hdr *hdr, void *pl, int pl_len, void *ud)
+{
+ struct ubx_aid_hui *aid_hui = pl;
+ struct gps_assist_data *gps = ud;
+
+ //printf("[.] AID_HUI\n");
+
+ if (aid_hui->flags & 0x2) { /* UTC parameters valid */
+ struct gps_utc_model *utc = &gps->utc;
+
+ gps->fields |= GPS_FIELD_UTC;
+
+ utc->a0 = double_to_fixedpoint(aid_hui->utc_a0, -30);
+ utc->a1 = double_to_fixedpoint(aid_hui->utc_a1, -50);
+ utc->delta_t_ls = aid_hui->utc_ls;
+ utc->t_ot = aid_hui->utc_tot >> 12;
+ utc->wn_t = aid_hui->utc_wnt;
+ utc->wn_lsf = aid_hui->utc_wnf;
+ utc->dn = aid_hui->utc_dn;
+ utc->delta_t_lsf = aid_hui->utc_lsf;
+ }
+
+ if (aid_hui->flags & 0x04) { /* Klobuchar parameters valid */
+ struct gps_ionosphere_model *iono = &gps->ionosphere;
+
+ gps->fields |= GPS_FIELD_IONOSPHERE;
+
+ iono->alpha_0 = float_to_fixedpoint(aid_hui->klob_a0, -30);
+ iono->alpha_1 = float_to_fixedpoint(aid_hui->klob_a1, -27);
+ iono->alpha_2 = float_to_fixedpoint(aid_hui->klob_a2, -24);
+ iono->alpha_3 = float_to_fixedpoint(aid_hui->klob_a3, -24);
+ iono->beta_0 = float_to_fixedpoint(aid_hui->klob_b0, 11);
+ iono->beta_1 = float_to_fixedpoint(aid_hui->klob_b1, 14);
+ iono->beta_2 = float_to_fixedpoint(aid_hui->klob_b2, 16);
+ iono->beta_3 = float_to_fixedpoint(aid_hui->klob_b3, 16);
+ }
+}
+
+static void
+_ubx_msg_parse_aid_alm(struct ubx_hdr *hdr, void *pl, int pl_len, void *ud)
+{
+ struct ubx_aid_alm *aid_alm = pl;
+ struct gps_assist_data *gps = ud;
+
+ //printf("[.] AID_ALM %d - %d\n", aid_alm->sv_id, aid_alm->gps_week);
+
+ if (aid_alm->gps_week) {
+ gps->fields |= GPS_FIELD_ALMANAC;
+ gps->almanac.wna = aid_alm->gps_week & 0xff;
+ gps_unpack_sf45_almanac(aid_alm->alm_words, &gps->almanac.svs[gps->almanac.n_sv++]);
+ }
+}
+
+static void
+_ubx_msg_parse_aid_eph(struct ubx_hdr *hdr, void *pl, int pl_len, void *ud)
+{
+ struct ubx_aid_eph *aid_eph = pl;
+ struct gps_assist_data *gps = ud;
+
+ //printf("[.] AID_EPH %d - %s\n", aid_eph->sv_id, aid_eph->present ? "present" : "not present");
+
+ if (aid_eph->present) {
+ int i = gps->ephemeris.n_sv++;
+ gps->fields |= GPS_FIELD_EPHEMERIS;
+ gps->ephemeris.svs[i].sv_id = aid_eph->sv_id;
+ gps_unpack_sf123(aid_eph->eph_words, &gps->ephemeris.svs[i]);
+ }
+}
+
+
+/* Dispatch table */
+struct ubx_dispatch_entry ubx_parse_dt[] = {
+ UBX_DISPATCH(NAV, POSLLH, _ubx_msg_parse_nav_posllh),
+ UBX_DISPATCH(AID, INI, _ubx_msg_parse_aid_ini),
+ UBX_DISPATCH(AID, HUI, _ubx_msg_parse_aid_hui),
+ UBX_DISPATCH(AID, ALM, _ubx_msg_parse_aid_alm),
+ UBX_DISPATCH(AID, EPH, _ubx_msg_parse_aid_eph),
+};
+