From ac7c48b4dee99d4c772f133d70d8d1b38262fcd2 Mon Sep 17 00:00:00 2001
From: Author Name <david@rowetel.com>
Date: Fri, 7 Jul 2023 12:20:59 +0930
Subject: shallow zip-file copy from codec2 e9d726bf20

---
 demo/freedv_datac1_tx.c | 96 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 96 insertions(+)
 create mode 100644 demo/freedv_datac1_tx.c

(limited to 'demo/freedv_datac1_tx.c')

diff --git a/demo/freedv_datac1_tx.c b/demo/freedv_datac1_tx.c
new file mode 100644
index 0000000..616eec8
--- /dev/null
+++ b/demo/freedv_datac1_tx.c
@@ -0,0 +1,96 @@
+/*---------------------------------------------------------------------------*\
+
+  FILE........: freedv_datac1_tx.c
+  AUTHOR......: David Rowe
+  DATE CREATED: April 2021
+
+  Demonstrates transmitting frames of raw data bytes using the FreeDV API datac1
+  mode.  The data on stdin is transmitted as a sequence of modulated bursts. 
+
+  Format of each burst: ...|preamble|data frame|postamble|silence|....
+  
+  There is just one data frame per burst in this demo.
+  
+  usage:
+  
+  cd codec2/build_linux
+  head -c $((510*10)) </dev/urandom > binaryIn.bin
+  cat binaryIn.bin | ./demo/freedv_datac1_tx | ./demo/freedv_datac1_rx > binaryOut.bin
+  diff binaryIn.bin binaryOut.bin
+  
+  Listen to the modulated Tx signal:
+  
+  cat binaryIn.bin | ./demo/freedv_datac1_tx | aplay -f S16_LE
+  
+\*---------------------------------------------------------------------------*/
+
+/*
+  Copyright (C) 2021 David Rowe
+
+  All rights reserved.
+
+  This program is free software; you can redistribute it and/or modify
+  it under the terms of the GNU Lesser General Public License version 2.1, as
+  published by the Free Software Foundation.  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 Lesser General Public License
+  along with this program; if not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <assert.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdint.h>
+
+#include "freedv_api.h"
+
+int main(int argc, char *argv[]) {
+    struct freedv            *freedv;
+
+    freedv = freedv_open(FREEDV_MODE_DATAC1);
+    assert(freedv != NULL);
+
+    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);
+    uint8_t bytes_in[bytes_per_modem_frame];
+    short mod_out_short[n_mod_out];
+    
+    for(int b=0; b<10; b++) {
+        /* send preamble */
+        int n_preamble = freedv_rawdatapreambletx(freedv, mod_out_short);
+        fwrite(mod_out_short, sizeof(short), n_preamble, stdout);
+        
+        /* read our input data frame from stdin */
+        size_t nread = fread(bytes_in, sizeof(uint8_t), payload_bytes_per_modem_frame, stdin);
+        if (nread != payload_bytes_per_modem_frame) break;
+
+        /* 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);
+        fwrite(mod_out_short, sizeof(short), n_mod_out, stdout);
+                    
+        /* send postamble */
+        int n_postamble = freedv_rawdatapostambletx(freedv, mod_out_short);
+        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;
+        fwrite(sil_short, sizeof(short), samples_delay, stdout);
+    }
+
+    freedv_close(freedv);
+
+    return 0;
+}
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