added the initials of the modem wrapper and skeleton of broadcast

datalink/Makefile

@@ -46,9 +46,9 @@ LDFLAGS=$(FFAUDIO_LINKFLAGS) -lm
 
 all: ../modem
 
-../modem: main.o arq.o net.o fsm.o arith.o crc6.o ../freedv/libfreedvdata.a ../audioio/audioio.a \
+../modem: main.o arq.o net.o fsm.o arith.o crc6.o modem.o ../freedv/libfreedvdata.a ../audioio/audioio.a \
 		../common/os_interop.o ../common/ring_buffer_posix.o ../common/shm_posix.o
-	$(CC) -o ../modem main.o arq.o net.o fsm.o arith.o crc6.o ../freedv/libfreedvdata.a ../audioio/audioio.a \
+	$(CC) -o ../modem main.o arq.o net.o fsm.o arith.o crc6.o modem.o ../freedv/libfreedvdata.a ../audioio/audioio.a \
 		../common/os_interop.o ../common/ring_buffer_posix.o ../common/shm_posix.o $(LDFLAGS)
 
 main.o: main.c
@@ -69,5 +69,8 @@ arith.o: arith.c
 crc6.o: crc6.c
 	$(CC) $(CFLAGS) -c crc6.c
 
+modem.o: modem.c
+	$(CC) $(CFLAGS) -c modem.c
+
 clean:
 	rm -f *.o

datalink/broadcast.c

@@ -0,0 +1,20 @@
+/* HERMES Modem
+ *
+ * Copyright (C) 2025 Rhizomatica
+ * Author: Rafael Diniz <rafael@riseup.net>
+ *
+ * This 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 3, or (at your option)
+ * any later version.
+ *
+ * This software 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 <https://www.gnu.org/licenses/>.
+ *
+ */
+

datalink/broadcast.h

@@ -0,0 +1,25 @@
+/* HERMES Modem
+ *
+ * Copyright (C) 2025 Rhizomatica
+ * Author: Rafael Diniz <rafael@riseup.net>
+ *
+ * This 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 3, or (at your option)
+ * any later version.
+ *
+ * This software 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 <https://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef BROADCAST_H_
+#define BROADCAST_H_
+
+
+#endif // BROADCAST_H_

datalink/main.c

@@ -32,8 +32,9 @@
 
 
 #include "freedv_api.h"
+#include "ldpc_codes.h"
 #include "arq.h"
-
+#include "modem.h"
 #include "defines.h"
 #include "audioio/audioio.h"
 
@@ -202,6 +203,10 @@ int main(int argc, char *argv[])
             freedv_close(freedv);
 
         }
+
+        printf("Available LDPC codes:\n");
+        ldpc_codes_list();
+
         return EXIT_SUCCESS;
     }
 
@@ -341,9 +346,13 @@ int main(int argc, char *argv[])
         audioio_init_internal(input_dev, output_dev, audio_system, &radio_capture, &radio_playback);
     }
 
-    
+
+    printf("Initializing ARQ modem on TCP port %d\n", base_tcp_port);
     arq_init(base_tcp_port, mod_config);
 
+    printf("Initializing Modem\n");
+    struct freedv *freedv = NULL;
+    init_modem(&freedv, mod_config);
 
     if (audio_system == AUDIO_SUBSYSTEM_SHM)
     {

datalink/modem.c

@@ -0,0 +1,105 @@
+/* HERMES Modem
+ *
+ * Copyright (C) 2025 Rhizomatica
+ * Author: Rafael Diniz <rafael@riseup.net>
+ *
+ * This 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 3, or (at your option)
+ * any later version.
+ *
+ * This software 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 <https://www.gnu.org/licenses/>.
+ *
+ */
+
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <pthread.h>
+#include <stdint.h>
+
+#include "modem.h"
+
+#include "freedv_api.h"
+#include "fsk.h"
+#include "ldpc_codes.h"
+#include "ofdm_internal.h"
+
+#include "defines.h"
+
+int init_modem(struct freedv **freedv, int mode)
+{
+    char codename[80] = "H_256_512_4";
+    struct freedv_advanced adv = {0, 2, 100, 8000, 1000, 200, codename};
+
+    if (mode == FREEDV_MODE_FSK_LDPC)
+        *freedv = freedv_open_advanced(mode, &adv);
+    else 
+        *freedv = freedv_open(mode);
+    
+    freedv_set_frames_per_burst(*freedv, 1);
+    
+    return 0;
+}
+
+int send_modulated_data(struct freedv *freedv, uint8_t *bytes_in, int frames_per_burst)
+{
+    size_t bytes_per_modem_frame = freedv_get_bits_per_modem_frame(freedv) / 8;
+    size_t payload_bytes_per_modem_frame =
+        bytes_per_modem_frame - 2; /* 16 bits used for the CRC */
+    size_t n_mod_out = freedv_get_n_tx_modem_samples(freedv);
+    short mod_out_short[n_mod_out];
+
+    /* send preamble */
+    int n_preamble = freedv_rawdatapreambletx(freedv, mod_out_short);
+    // TODO: write to buffer
+    // fwrite(mod_out_short, sizeof(short), n_preamble, stdout);
+
+    
+    /* The raw data modes require a CRC in the last two bytes */
+    uint16_t crc16 = freedv_gen_crc16(bytes_in, payload_bytes_per_modem_frame);
+    bytes_in[bytes_per_modem_frame - 2] = crc16 >> 8;
+    bytes_in[bytes_per_modem_frame - 1] = crc16 & 0xff;
+
+    /* modulate and send a data frame */
+    freedv_rawdatatx(freedv, mod_out_short, bytes_in);
+    // TODO: write to buffer
+    // fwrite(mod_out_short, sizeof(short), n_mod_out, stdout);
+
+    /* send postamble */
+    int n_postamble = freedv_rawdatapostambletx(freedv, mod_out_short);
+    // TODO: write to buffer
+    // fwrite(mod_out_short, sizeof(short), n_postamble, stdout);
+
+    /* create some silence between bursts */
+    int inter_burst_delay_ms = 200;
+    int samples_delay = FREEDV_FS_8000 * inter_burst_delay_ms / 1000;
+    short sil_short[samples_delay];
+    for (int i = 0; i < samples_delay; i++) sil_short[i] = 0;
+    // TODO: write to buffer
+    // fwrite(sil_short, sizeof(short), samples_delay, stdout);
+    
+    return 0;
+}
+
+int receive_modulated_data(struct freedv *freedv, uint8_t *bytes_out, size_t *nbytes_out)
+{
+    int input_size = freedv_get_n_max_modem_samples(freedv);
+
+    // TODO: read from buffer
+    short demod_in[freedv_get_n_max_modem_samples(freedv)];
+
+    size_t nin = freedv_nin(freedv);
+
+    *nbytes_out = freedv_rawdatarx(freedv, bytes_out, demod_in);
+
+    return 0;
+}

datalink/modem.h

@@ -0,0 +1,38 @@
+/* HERMES Modem
+ *
+ * Copyright (C) 2025 Rhizomatica
+ * Author: Rafael Diniz <rafael@riseup.net>
+ *
+ * This 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 3, or (at your option)
+ * any later version.
+ *
+ * This software 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 <https://www.gnu.org/licenses/>.
+ *
+ */
+
+
+#ifndef MODEM_H
+#define MODEM_H
+
+#include <stdint.h>
+#include <stdbool.h>
+
+#include "freedv_api.h"
+
+int init_modem(struct freedv **freedv, int mode);
+
+// always send the frame size in bytes_in
+int send_modulated_data(struct freedv *freedv, uint8_t *bytes_in, int frames_per_burst);
+
+int receive_modulated_data(struct freedv *freedv, uint8_t *bytes_out, size_t *nbytes_out);
+
+
+#endif // MODEM_H