packet_mod: implement FEC and modulation for the header

impl/src/packet_mod.c

@@ -15,6 +15,9 @@ result_t packet_mod_init(packet_mod_ctx_t *ctx)
 	ctx->fec   = fec_create(CHANNEL_CODE, NULL);
 	ctx->modem = modem_create(MODULATION);
 
+	ctx->hdr_fec   = fec_create(HEADER_CHANNEL_CODE, NULL);
+	ctx->hdr_modem = modem_create(HEADER_MODULATION);
+
 	ctx->state = NOT_STARTED;
 
 	return OK;
@@ -48,6 +51,9 @@ result_t packet_mod_free(packet_mod_ctx_t *ctx)
 	fec_destroy(ctx->fec);
 	modem_destroy(ctx->modem);
 
+	fec_destroy(ctx->hdr_fec);
+	modem_destroy(ctx->hdr_modem);
+
 	return OK;
 }
 
@@ -153,18 +159,16 @@ result_t packet_mod_add_header(packet_mod_ctx_t *ctx)
 	header[2] = (ctx->raw_data_crc >> 8) & 0xFF;
 	header[3] = (ctx->raw_data_crc >> 0) & 0xFF;
 
-	// the header is coded and modulated differently than the data.
-	fec   hdr_fec   = fec_create(HEADER_CHANNEL_CODE, NULL);
-	modem hdr_modem = modem_create(HEADER_MODULATION);
+	// note: the header is coded and modulated differently than the data.
 
 	// encode the header
 	unsigned int hdr_enc_length = fec_get_enc_msg_length(HEADER_CHANNEL_CODE, sizeof(header));
 	unsigned char header_encoded[hdr_enc_length];
 
-	ERR_CHECK_LIQUID(fec_encode(hdr_fec, sizeof(header), header, header_encoded));
+	ERR_CHECK_LIQUID(fec_encode(ctx->hdr_fec, sizeof(header), header, header_encoded));
 
 	// modulate the header
-	unsigned int bps = modem_get_bps(hdr_modem);
+	unsigned int bps = modem_get_bps(ctx->hdr_modem);
 	unsigned int nsyms = (hdr_enc_length * 8 + bps/2) / bps;
 
 	unsigned char header_sym_idcs[nsyms];
@@ -173,7 +177,7 @@ result_t packet_mod_add_header(packet_mod_ctx_t *ctx)
 	ERR_CHECK_LIQUID(liquid_repack_bytes(header_encoded, 8, hdr_enc_length, header_sym_idcs, bps, nsyms, &nsyms));
 
 	for(size_t i = 0; i < nsyms; i++) {
-		ERR_CHECK_LIQUID(modem_modulate(hdr_modem, header_sym_idcs[i], &header_mod[i]));
+		ERR_CHECK_LIQUID(modem_modulate(ctx->hdr_modem, header_sym_idcs[i], &header_mod[i]));
 	}
 
 	// concatenate the modulated header and message
@@ -228,6 +232,29 @@ result_t packet_mod_add_preamble(packet_mod_ctx_t *ctx)
 }
 
 
+result_t packet_mod_get_result_b(packet_mod_ctx_t *ctx, unsigned char *data, size_t *length)
+{
+	if(!((ctx->state == DATA_RAW) || (ctx->state == DATA_CODED))) {
+		return ERR_INVALID_STATE;
+	}
+
+	if(!data) {
+		// data is NULL, so we only return the required length
+		*length = ctx->length;
+		return OK;
+	}
+
+	if(*length < ctx->length) {
+		return ERR_NO_MEM;
+	}
+
+	*length = ctx->length;
+	memcpy(data, ctx->pkt_bytes, *length * sizeof(unsigned char));
+
+	return OK;
+}
+
+
 result_t packet_mod_get_result_cf(packet_mod_ctx_t *ctx, float complex *data, size_t *length)
 {
 	if(!((ctx->state == DATA_MODULATED) || (ctx->state == HEADER_ADDED) || (ctx->state == PREAMBLE_ADDED))) {

impl/src/packet_mod.h

@@ -1,5 +1,5 @@
-#ifndef PACKET_MOD
-#define PACKET_MOD
+#ifndef PACKET_MOD_H
+#define PACKET_MOD_H
 
 #include <stdlib.h>
 #include <complex.h>
@@ -28,6 +28,9 @@ typedef struct
 	modem modem;
 	fec   fec;
 
+	modem hdr_modem;
+	fec   hdr_fec;
+
 	uint16_t raw_data_crc;
 
 	size_t length;
@@ -121,19 +124,6 @@ result_t packet_mod_add_header(packet_mod_ctx_t *ctx);
  */
 result_t packet_mod_add_preamble(packet_mod_ctx_t *ctx);
 
-
-/*!\brief Dump the internal data to the given file.
- *
- * The format of the resulting file depends on the current state of the packet
- * modulation context.
- *
- * \param[in] ctx       The context to use for this operation.
- * \param[in] filename  Name of the file to write to.
- * \returns             An result code (see results.h).
- */
-result_t packet_mod_dump(packet_mod_ctx_t *ctx, const char *filename);
-
-
 /*!\brief Get the result data as raw bytes.
  *
  * Raw bytes can be retrieved after \ref packet_mod_set_data() and \ref
@@ -175,4 +165,4 @@ result_t packet_mod_get_result_b(packet_mod_ctx_t *ctx, unsigned char *data, siz
  */
 result_t packet_mod_get_result_cf(packet_mod_ctx_t *ctx, float complex *data, size_t *length);
 
-#endif // PACKET_MOD
+#endif // PACKET_MOD_H