Move the transmission chain to a separate "tx" module
This commit is contained in:
Thomas Kolb
parent
97772fa12b
commit
a5634ed736
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@ -23,6 +23,8 @@ set(sources
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src/layer1/results.h
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src/layer1/transmission.c
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src/layer1/transmission.h
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src/layer1/tx.c
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src/layer1/tx.h
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src/layer1/whitening.c
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src/layer1/whitening.h
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)
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@ -96,3 +96,24 @@ result_t transmission_filter_packet(
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return OK;
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}
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size_t transmission_calculate_ramp_up_length(transmission_ctx_t *ctx)
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{
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(void)ctx;
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return RRC_SPS * TRANSMISSION_RAMP_UP_LEN;
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}
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size_t transmission_calculate_ramp_down_length(transmission_ctx_t *ctx)
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{
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(void)ctx;
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return RRC_SPS * TRANSMISSION_RAMP_DOWN_LEN;
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}
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size_t transmission_calculate_packet_length(transmission_ctx_t *ctx, size_t symbol_count)
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{
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(void)ctx;
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return RRC_SPS * symbol_count;
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}
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@ -76,4 +76,29 @@ result_t transmission_filter_packet(
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size_t *output_size);
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/*!\brief Calculate the number of samples required for ramp-up.
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*
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* \param ctx Pointer to the transmission context.
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* \returns The number of samples required.
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*/
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size_t transmission_calculate_ramp_up_length(transmission_ctx_t *ctx);
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/*!\brief Calculate the number of samples required for ramp-down.
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*
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* \param ctx Pointer to the transmission context.
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* \returns The number of samples required.
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*/
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size_t transmission_calculate_ramp_down_length(transmission_ctx_t *ctx);
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/*!\brief Calculate the number of samples required for the given number of packet symbols.
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*
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* \param ctx Pointer to the transmission context.
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* \param symbol_count Size of the packet in symbols.
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* \returns The number of samples required.
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*/
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size_t transmission_calculate_packet_length(transmission_ctx_t *ctx, size_t symbol_count);
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#endif // LAYER1_TRANSMISSION_H
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@ -0,0 +1,168 @@
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#include <stdbool.h>
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#include <malloc.h>
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#include "layer1/results.h"
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#include "tx.h"
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static inline bool resize_buffer(layer1_tx_t *tx, size_t new_size)
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{
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void *tmpptr = realloc(tx->samples, new_size * sizeof(*(tx->samples)));
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if(tmpptr) {
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tx->samples = tmpptr;
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tx->samples_allocated = new_size;
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return true;
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} else {
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return false;
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}
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}
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static inline bool can_append_n_samples(layer1_tx_t *tx, size_t samples)
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{
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return (tx->samples_used + samples) <= tx->samples_allocated;
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}
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static inline size_t get_free_space(layer1_tx_t *tx)
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{
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return tx->samples_allocated - tx->samples_used;
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}
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static inline float complex* get_write_ptr(layer1_tx_t *tx)
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{
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return tx->samples + tx->samples_used;
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}
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result_t layer1_tx_init(layer1_tx_t *tx)
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{
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tx->samples = NULL;
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tx->samples_allocated = 0;
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tx->samples_used = 0;
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transmission_init(&tx->transmission);
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packet_mod_init(&tx->pmod);
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return OK;
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}
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result_t layer1_tx_shutdown(layer1_tx_t *tx)
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{
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if(tx->samples) {
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free(tx->samples);
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tx->samples = NULL;
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}
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tx->samples_allocated = 0;
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tx->samples_used = 0;
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transmission_free(&tx->transmission);
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packet_mod_free(&tx->pmod);
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return OK;
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}
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result_t layer1_tx_reset(layer1_tx_t *tx)
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{
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tx->samples_used = 0;
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return OK;
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}
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result_t layer1_tx_add_packet_to_burst(layer1_tx_t *tx, const uint8_t *data, size_t length)
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{
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if(tx->samples_used == 0) {
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if(!resize_buffer(tx, 4096 + transmission_calculate_ramp_up_length(&tx->transmission))) {
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return ERR_NO_MEM;
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}
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// nothing is in the buffer yet, so we must first generate a ramp-up.
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size_t len = get_free_space(tx);
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result_t res = transmission_ramp_up(&tx->transmission, get_write_ptr(tx), &len);
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if(res != OK) {
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printf("Ramp-up requires %zd samples at offset %zd.\n", len, tx->samples_used);
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return res;
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}
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tx->samples_used += len;
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}
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// encode and modulate the packet
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packet_mod_set_data(&tx->pmod, data, length);
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packet_mod_encode(&tx->pmod);
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packet_mod_modulate(&tx->pmod);
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packet_mod_add_header(&tx->pmod);
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packet_mod_add_preamble(&tx->pmod);
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// determine number of symbols in the packet
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size_t nsyms;
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packet_mod_get_result_cf(&tx->pmod, NULL, &nsyms);
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// calculate the number of filtered samples
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size_t filtered_size = transmission_calculate_packet_length(&tx->transmission, nsyms);
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// resize the buffer if necessary (and add some reserve)
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if(!can_append_n_samples(tx, filtered_size)) {
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if(!resize_buffer(tx, tx->samples_allocated + 2*filtered_size)) {
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return ERR_NO_MEM;
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}
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}
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// store the packet symbols into a temporary buffer
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float complex msg_mod[nsyms];
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packet_mod_get_result_cf(&tx->pmod, msg_mod, &nsyms);
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// filter the packet and append it to the output buffer
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size_t len = get_free_space(tx);
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result_t res = transmission_filter_packet(&tx->transmission, msg_mod, nsyms, get_write_ptr(tx), &len);
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if(res != OK) {
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printf("Packet requires %zd samples at offset %zd.\n", len, tx->samples_used);
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return res;
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}
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tx->samples_used += len;
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return OK;
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}
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result_t layer1_tx_finalize_burst(layer1_tx_t *tx)
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{
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// calculate the number of samples for the ramp down
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size_t len = transmission_calculate_ramp_down_length(&tx->transmission);
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// resize the buffer if necessary
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if(!can_append_n_samples(tx, len)) {
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if(!resize_buffer(tx, tx->samples_allocated + len)) {
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return ERR_NO_MEM;
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}
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}
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// generate the ramp-down
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len = get_free_space(tx);
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result_t res = transmission_ramp_down(&tx->transmission, get_write_ptr(tx), &len);
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if(res != OK) {
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printf("Ramp-down requires %zd samples at offset %zd.\n", len, tx->samples_used);
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return res;
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}
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tx->samples_used += len;
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return OK;
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}
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size_t layer1_tx_get_sample_count(const layer1_tx_t *tx)
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{
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return tx->samples_used;
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}
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const float complex* layer1_tx_get_sample_data(const layer1_tx_t *tx)
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{
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return tx->samples;
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}
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@ -0,0 +1,103 @@
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#ifndef LAYER1_TX_H
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#define LAYER1_TX_H
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#include <complex.h>
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#include <stddef.h>
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#include <stdint.h>
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#include "results.h"
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#include "transmission.h"
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#include "packet_mod.h"
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typedef struct
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{
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float complex *samples;
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size_t samples_allocated;
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size_t samples_used;
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transmission_ctx_t transmission;
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packet_mod_ctx_t pmod;
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} layer1_tx_t;
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/*!
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* \brief Initialize the transmitter.
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*
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* \param tx Pointer to the transmitter context.
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* \returns The result of the initialization.
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*/
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result_t layer1_tx_init(layer1_tx_t *tx);
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/*!
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* \brief Shut the transmitter down. Frees all memory.
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*
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* \param tx Pointer to the transmitter context.
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* \returns The result of the shutdown.
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*/
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result_t layer1_tx_shutdown(layer1_tx_t *tx);
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/*!
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* \brief Reset the transmitter.
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*
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* Logically removes all internal data, but does not free memory.
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*
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* \param tx Pointer to the transmitter context.
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* \returns The result of the reset.
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*/
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result_t layer1_tx_reset(layer1_tx_t *tx);
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/*!
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* \brief Add a packet to the burst.
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*
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* Encodes the raw data, modulates it, applies pulse filtering and appends the
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* result to the internal buffer.
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*
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* If the buffer is empty (after init or reset), it first generates a ramp-up
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* sequence.
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*
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* You can add arbitrarily many packets, the only limit is the available memory.
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*
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* \param tx Pointer to the transmitter context.
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* \param data Pointer to the packet’s raw data.
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* \param length The number of bytes in the data array.
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* \returns The result of the operation.
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*/
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result_t layer1_tx_add_packet_to_burst(layer1_tx_t *tx, const uint8_t *data, size_t length);
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/*!
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* \brief Generate the ramp-down sequence.
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*
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* The burst is considered complete after calling this function. You should
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* retrieve the generated samples and call \ref layer1_tx_reset() before adding
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* further packets.
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*
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* \param tx Pointer to the transmitter context.
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* \returns The result of the finalization.
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*/
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result_t layer1_tx_finalize_burst(layer1_tx_t *tx);
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/*!
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* \brief Retrieve the number of generated samples.
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*
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* \param tx Pointer to the transmitter context.
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* \returns The number of samples returned by \ref layer1_tx_get_sample_data().
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*/
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size_t layer1_tx_get_sample_count(const layer1_tx_t *tx);
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/*!
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* \brief Retrieve the generated samples.
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*
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* Calling this after \ref layer1_tx_finalize_burst() returns the complete burst ready for transmission.
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*
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* \param tx Pointer to the transmitter context.
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* \returns A pointer to the generated samples.
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*/
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const float complex* layer1_tx_get_sample_data(const layer1_tx_t *tx);
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#endif // LAYER1_TX_H
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@ -6,13 +6,20 @@
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#include "utils.h"
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#include "layer1/results.h"
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#include "layer1/packet_mod.h"
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#include "layer1/config.h"
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#include "layer1/preamble.h"
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#include "layer1/transmission.h"
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#include "layer1/correlator.h"
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#include "layer1/freq_est.h"
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#include "layer1/whitening.h"
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#include "layer1/tx.h"
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#define RESULT_CHECK(stmt) { \
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result_t res = stmt; \
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if(res != OK) { \
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printf("Error %d in %s:%d!", res, __FILE__, __LINE__); \
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exit(1); \
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} \
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}
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typedef enum {
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RX_STATE_ACQUISITION,
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@ -45,7 +52,18 @@ int main(void)
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{
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uint8_t msg_org[] = "Hello Liquid! This is the message to transmit. Hopefully it can be decoded correctly...";
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uint8_t header[4];
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layer1_tx_t tx;
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RESULT_CHECK(layer1_tx_init(&tx));
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RESULT_CHECK(layer1_tx_add_packet_to_burst(&tx, msg_org, sizeof(msg_org)));
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RESULT_CHECK(layer1_tx_finalize_burst(&tx));
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size_t burst_len = layer1_tx_get_sample_count(&tx);
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const float complex *whole_burst = layer1_tx_get_sample_data(&tx);
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dump_array_cf(whole_burst, burst_len, 1.0f, "/tmp/tx.cpx");
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// ** RX starts here **
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fec hdr_fec = fec_create(HEADER_CHANNEL_CODE, NULL);
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fec payload_fec = fec_create(PAYLOAD_CHANNEL_CODE, NULL);
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@ -60,54 +78,12 @@ int main(void)
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channel_cccf_add_carrier_offset(channel, 0.20f, 1.00f);
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// precalculate encoded header length in symbols
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uint8_t header[4];
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unsigned int hdr_len_enc_bytes = fec_get_enc_msg_length(HEADER_CHANNEL_CODE, sizeof(header));
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unsigned int hdr_bps = modem_get_bps(hdr_demod);
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unsigned int hdr_len_symbols = (hdr_len_enc_bytes * 8 + hdr_bps - 1) / hdr_bps;
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packet_mod_ctx_t pmod;
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packet_mod_init(&pmod);
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packet_mod_set_data(&pmod, msg_org, sizeof(msg_org));
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packet_mod_encode(&pmod);
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packet_mod_modulate(&pmod);
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packet_mod_add_header(&pmod);
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packet_mod_add_preamble(&pmod);
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size_t nsyms;
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packet_mod_get_result_cf(&pmod, NULL, &nsyms); // determine number of symbols for allocation
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float complex msg_mod[nsyms];
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packet_mod_get_result_cf(&pmod, msg_mod, &nsyms); // get the data
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size_t burst_len = 0;
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float complex whole_burst[65536];
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size_t len;
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transmission_ctx_t transm;
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transmission_init(&transm);
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len = 65536-burst_len;
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if(transmission_ramp_up(&transm, whole_burst+burst_len, &len) != OK) {
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printf("Ramp-up requires %zd symbols at offset %zd.\n", len, burst_len);
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return 1;
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}
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burst_len += len;
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len = 65536-burst_len;
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if(transmission_filter_packet(&transm, msg_mod, nsyms, whole_burst+burst_len, &len) != OK) {
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printf("Packet requires %zd symbols at offset %zd.\n", len, burst_len);
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return 1;
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}
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burst_len += len;
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len = 65536-burst_len;
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if(transmission_ramp_down(&transm, whole_burst+burst_len, &len) != OK) {
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printf("Ramp-down requires %zd symbols at offset %zd.\n", len, burst_len);
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return 1;
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}
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burst_len += len;
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dump_array_cf(whole_burst, burst_len, 1.0f, "/tmp/tx.cpx");
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// channel
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float complex msg_received[burst_len];
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