Signed-off-by: Konke Radlow <koradlow@xxxxxxxxx>
---
lib/include/libv4l2rds.h | 39 +++++++++++
lib/libv4l2rds/libv4l2rds.c | 159 +++++++++++++++++++++++++++++++++++++++++--
2 files changed, 194 insertions(+), 4 deletions(-)
diff --git a/lib/include/libv4l2rds.h b/lib/include/libv4l2rds.h
index 62b28bc..45dc2d1 100644
--- a/lib/include/libv4l2rds.h
+++ b/lib/include/libv4l2rds.h
@@ -50,6 +50,10 @@ extern "C" {
* Additional data is limited to 112 bit, and the smallest
* optional tuple has a size of 4 bit (4 bit identifier +
* 0 bits of data) */
+#define MAX_TMC_ALT_STATIONS 32 /* defined by ISO 14819-1:2003, 7.5.3.3 */
+#define MAX_TMC_AF_CNT 4 /* limit for the numbers of AFs stored per alternative TMC
+ * station. This value is not defined by the standard, but based on observation
+ * of real-world RDS-TMC streams */
#define MAX_EON_CNT 20 /* Maximal number of entries in the EON table (for storing
* information about other radio stations, broadcasted
* by the current station) */
@@ -75,6 +79,7 @@ extern "C" {
#define V4L2_RDS_TMC_SYS 0x10000 /* RDS-TMC system information */
#define V4L2_RDS_EON 0x20000 /* Enhanced Other Network Info */
#define V4L2_RDS_LSF 0x40000 /* Linkage information */
+#define V4L2_RDS_TMC_TUNING 0x80000 /* RDS-TMC tuning information */
/* Define Constants for the state of the RDS decoding process
* used to address the relevant bit in the decode_information bitmask */
@@ -175,6 +180,37 @@ struct v4l2_rds_eon_set {
* radio channels */
};
+/* struct to encapsulate alternative frequencies (AFs) for RDS-TMC stations.
+ * AFs listed in af[] can be used unconditionally.
+ * AFs listed in mapped_af[n] should only be used if the current
+ * tuner frequency matches the value in mapped_af_tuning[n] */
+struct v4l2_tmc_alt_freq {
+ uint8_t af_size; /* number of known AFs */
+ uint8_t af_index;
+ uint8_t mapped_af_size; /* number of mapped AFs */
+ uint8_t mapped_af_index;
+ uint32_t af[MAX_TMC_AF_CNT]; /* AFs defined in Hz */
+ uint32_t mapped_af[MAX_TMC_AF_CNT]; /* mapped AFs defined in Hz */
+ uint32_t mapped_af_tuning[MAX_TMC_AF_CNT]; /* mapped AFs defined in Hz */
+};
+
+/* struct to encapsulate information about stations carrying RDS-TMC services */
+struct v4l2_tmc_station {
+ uint16_t pi;
+ uint8_t ltn; /* database-ID of ON */
+ uint8_t msg; /* msg parameters of ON */
+ uint8_t sid; /* service-ID of ON */
+ struct v4l2_tmc_alt_freq afi;
+};
+
+/* struct to encapsulate tuning information for TMC */
+struct v4l2_tmc_tuning {
+ uint8_t station_cnt; /* number of announced alternative stations */
+ uint8_t index;
+ struct v4l2_tmc_station station[MAX_TMC_ALT_STATIONS]; /* information
+ * about other stations carrying the same RDS-TMC service */
+};
+
/* struct to encapsulate an additional data field in a TMC message */
struct v4l2_tmc_additional {
uint8_t label;
@@ -225,6 +261,9 @@ struct v4l2_rds_tmc {
uint8_t t_d; /* delay time (only if mode = enhanced */
uint8_t spn[9]; /* service provider name */
struct v4l2_rds_tmc_msg tmc_msg;
+
+ /* tuning information for alternative service providers */
+ struct v4l2_tmc_tuning tuning;
};
/* struct to encapsulate state and RDS information for current decoding process */
diff --git a/lib/libv4l2rds/libv4l2rds.c b/lib/libv4l2rds/libv4l2rds.c
index 3a90a3b..3995c3d 100644
--- a/lib/libv4l2rds/libv4l2rds.c
+++ b/lib/libv4l2rds/libv4l2rds.c
@@ -93,7 +93,9 @@ enum rds_state {
};
/* function declarations to prevent the need to move large code blocks */
+static int rds_add_tmc_station(struct rds_private_state *priv_state, uint16_t pi);
static uint32_t rds_decode_af(uint8_t af, bool is_vhf);
+static bool rds_add_tmc_af(struct rds_private_state *priv_state);
static inline uint8_t set_bit(uint8_t input, uint8_t bitmask, bool bitvalue)
{
@@ -437,6 +439,59 @@ static uint32_t rds_decode_tmc_multi_group(struct rds_private_state *priv_state)
return V4L2_RDS_TMC_MG;
}
+/* decode the RDS-TMC tuning information that is contained in type 8A groups
+ * (variants 4 to 9) that announce the presence alternative transmitters
+ * providing the same RDS-TMC service */
+static uint32_t rds_decode_tmc_tuning(struct rds_private_state *priv_state)
+{
+ struct v4l2_rds_group *group = &priv_state->rds_group;
+ struct v4l2_rds_tmc *tmc = &priv_state->handle.tmc;
+ uint8_t variant_code = group->data_b_lsb & 0x0f;
+ uint16_t pi_on = (group->data_d_msb << 8) | group->data_d_lsb;
+ uint8_t index;
+
+ /* variants 4 and 5 carry the service provider name */
+ if (variant_code >= 4 && variant_code <= 5) {
+ int offset = 4 * (variant_code - 4);
+ tmc->spn[0 + offset] = group->data_c_msb;
+ tmc->spn[1 + offset] = group->data_c_lsb;
+ tmc->spn[2 + offset] = group->data_d_msb;
+ tmc->spn[3 + offset] = group->data_d_lsb;
+
+ /* variant 6 provides specific frequencies for the same RDS-TMC service
+ * on a network with a different PI code */
+ /* variant 7 provides mapped frequency pair information which should only
+ * be used if the terminal is tuned to the tuning frequency */
+ } else if (variant_code == 6 || variant_code == 7) {
+ rds_add_tmc_af(priv_state);
+
+ /* variant 8 indicates up to 2 PI codes of adjacent networks carrying
+ * the same RDS-TMC service on all transmitters of the network */
+ } else if (variant_code == 8) {
+ uint16_t pi_on_2 = (group->data_c_msb << 8) | group->data_c_lsb;
+
+ /* try to add both transmitted PI codes to the table */
+ rds_add_tmc_station(priv_state, pi_on);
+ /* PI = 0 is used as a filler code */
+ if (pi_on_2 != 0) rds_add_tmc_station(priv_state, pi_on_2);
+
+ /* variant 9 provides PI codes of other networks with different system
+ * parameters */
+ } else if (variant_code == 9) {
+ index = rds_add_tmc_station(priv_state, pi_on);
+
+ /* bits 0 - 5 contain the service-ID of the ON */
+ tmc->tuning.station[index].sid = group->data_c_lsb & 0x3F;
+ /* bits 6-10 contain the msg parameters of the ON */
+ tmc->tuning.station[index].msg = (group->data_c_msb & 0x03) << 2;
+ tmc->tuning.station[index].msg |= (group->data_c_lsb >> 6) & 0x03;
+ /* bits 11-15 contain the database-ID of the ON */
+ tmc->tuning.station[index].ltn = group->data_c_msb >> 2;
+ }
+
+ return V4L2_RDS_TMC_TUNING;
+}
+
static bool rds_add_oda(struct rds_private_state *priv_state, struct v4l2_rds_oda oda)
{
struct v4l2_rds *handle = &priv_state->handle;
@@ -516,6 +571,103 @@ static bool rds_add_af(struct rds_private_state *priv_state)
return updated_af;
}
+/* checks if an entry for the given PI already exists and returns the index
+ * of that entry if so. Else it adds a new entry to the TMC-Tuning table and returns
+ * the index of the new field */
+static int rds_add_tmc_station(struct rds_private_state *priv_state, uint16_t pi)
+{
+ struct v4l2_tmc_tuning *tuning = &priv_state->handle.tmc.tuning;
+ uint8_t index = tuning->index;
+ uint8_t size = tuning->station_cnt;
+
+ /* check if there's an entry for the given PI key */
+ for (int i = 0; i < tuning->station_cnt; i++) {
+ if (tuning->station[i].pi == pi) {
+ return i;
+ }
+ }
+ /* if the the maximum table size is reached, overwrite old
+ * entries, starting at the oldest one = 0 */
+ tuning->station[index].pi = pi;
+ tuning->index = (index+1 < MAX_TMC_ALT_STATIONS)? (index+1) : 0;
+ tuning->station_cnt = (size+1 <= MAX_TMC_ALT_STATIONS)? (size+1) : MAX_TMC_ALT_STATIONS;
+ return index;
+}
+
+/* tries to add new AFs to the relevant entry in the list of RDS-TMC providers */
+static bool rds_add_tmc_af(struct rds_private_state *priv_state)
+{
+ struct v4l2_rds_group *grp = &priv_state->rds_group;
+ struct v4l2_tmc_alt_freq *afi;
+ uint16_t pi_on = grp->data_d_msb << 8 | grp->data_d_lsb;
+ uint8_t variant = grp->data_b_lsb & 0x0f;
+ uint8_t station_index = rds_add_tmc_station(priv_state, pi_on);
+ uint8_t af_index;
+ uint8_t mapped_af_index;
+ uint32_t freq_a = rds_decode_af(grp->data_c_msb, true);
+ uint32_t freq_b = rds_decode_af(grp->data_c_lsb, true);
+
+ afi = &priv_state->handle.tmc.tuning.station[station_index].afi;
+ af_index = afi->af_index;
+ mapped_af_index = afi->mapped_af_index;
+
+ /* specific frequencies */
+ if (variant == 6) {
+ /* compare the new AFs to the stored ones, reset them to 0 if the AFs are
+ * already known */
+ for (int i = 0; i < afi->af_size; i++) {
+ freq_a = (freq_a == afi->af[i])? 0 : freq_a;
+ freq_b = (freq_b == afi->af[i])? 0 : freq_b;
+ }
+ /* return early if there is nothing to do */
+ if (freq_a == 0 && freq_b == 0)
+ return false;
+
+ /* add the new AFs if they were previously unknown */
+ if (freq_a != 0) {
+ afi->af[af_index] = freq_a;
+ af_index = (af_index+1 < MAX_TMC_AF_CNT)? af_index+1 : 0;
+ afi->af_size++;
+ }
+ if (freq_b != 0) {
+ afi->af[af_index] = freq_b;
+ af_index = (af_index+1 < MAX_TMC_AF_CNT)? af_index+1 : 0;
+ afi->af_size++;
+ }
+ /* update the information in the handle */
+ afi->af_index = af_index;
+ if (afi->af_size >= MAX_TMC_AF_CNT)
+ afi->af_size = MAX_TMC_AF_CNT;
+
+ return true;
+ }
+
+ /* mapped frequency pair */
+ else if (variant == 7) {
+ /* check the if there's already a frequency mapped to the new tuning
+ * frequency, update the mapped frequency in this case */
+ for (int i = 0; i < afi->mapped_af_size; i++) {
+ if (freq_a == afi->mapped_af_tuning[i])
+ afi->mapped_af[i] = freq_b;
+ return true;
+ }
+ /* new pair is unknown, add it to the list */
+ if (freq_a != 0 && freq_b != 0) {
+ mapped_af_index = (mapped_af_index+1 >= MAX_TMC_AF_CNT)? 0 : mapped_af_index + 1;
+ afi->mapped_af[mapped_af_index] = freq_b;
+ afi->mapped_af_tuning[mapped_af_index] = freq_a;
+ afi->mapped_af_size++;
+ }
+ /* update the information in the handle */
+ afi->mapped_af_index = mapped_af_index;
+ if (afi->mapped_af_size >= MAX_TMC_AF_CNT)
+ afi->mapped_af_size = MAX_TMC_AF_CNT;
+
+ return true;
+ }
+ return false;
+}
+
/* adds one char of the ps name to temporal storage, the value is validated
* if it is received twice in a row
* @pos: position of the char within the PS name (0..7)
@@ -968,13 +1120,12 @@ static uint32_t rds_decode_group8(struct rds_private_state *priv_state)
!(grp->data_b_lsb & V4L2_TMC_TUNING_INFO)) {
return rds_decode_tmc_multi_group(priv_state);
}
- /* -> tuning information message, defined for variants 4..9, submitted
- * in bits 0-3 of block 2 */
+ /* -> tuning information message, defined for variants 4..9,
+ * submitted in bits 0-3 of block 2 */
tuning_variant = grp->data_b_lsb & 0x0f;
if ((grp->data_b_lsb & V4L2_TMC_TUNING_INFO) && tuning_variant >= 4 &&
tuning_variant <= 9) {
- /* TODO: Implement tuning information decoding */
- return 0;
+ return rds_decode_tmc_tuning(priv_state);
}
return 0;
--
1.7.10.4
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