Added stdin/stdout backend

.gitignore

@@ -1,4 +1,5 @@
 *.o
+*~
 .deps
 Makefile
 Makefile.in

INSTALL

@@ -12,7 +12,8 @@ without warranty of any kind.
 Basic Installation
 ==================
 
-   Briefly, the shell commands `./configure; make; make install' should
+   Briefly, the shell commands `./install-dependencies-linux.sh;
+autoreconf --install; ./configure; make; make install' should
 configure, build, and install this package.  The following
 more-detailed instructions are generic; see the `README' file for
 instructions specific to this package.  Some packages provide this

configure.ac

@@ -64,6 +64,17 @@ AS_IF([test "x$with_sndfile" = "xno"], [
 AC_DEFINE_UNQUOTED([USE_SNDFILE], [$use_sndfile],
                    [Define to 1 to enable sndfile support])
 
+#   stdio
+AC_ARG_WITH([stdio], AS_HELP_STRING([--without-stdio],
+            [build without stdio support]))
+AS_IF([test "x$with_stdio" = "xno"], [
+    use_stdio=0
+], [
+    use_stdio=1
+])
+AC_DEFINE_UNQUOTED([USE_STDIO], [$use_stdio],
+                   [Define to 1 to enable stdio support])
+
 #   benchmarks
 AC_ARG_WITH([benchmarks], AS_HELP_STRING([--disable-benchmarks],
             [build without internal benchmarks]))
@@ -81,6 +92,7 @@ option summary:
     benchmarks     $with_benchmarks ($use_benchmarks)
     pulseaudio     $with_pulseaudio ($use_pulseaudio)
     sndfile        $with_sndfile ($use_sndfile)
+    stdio          $with_stdio ($use_stdio)
     sndio          $with_sndio ($use_sndio)
 ])
 

src/Makefile.am

@@ -37,7 +37,8 @@ SIMPLEAUDIO_SRC = \
 	simpleaudio-alsa.c	\
 	simpleaudio-sndio.c	\
 	simpleaudio-benchmark.c	\
-	simpleaudio-sndfile.c
+	simpleaudio-sndfile.c   \
+        simpleaudio-stdio.c
 
 FSK_SRC = fsk.h fsk.c
 

src/minimodem.c

@@ -404,6 +404,7 @@ usage()
     "		    -5, --baudot	Baudot 5-N-1\n"
     "		    -u, --usos {0|1}\n"
     "		    -f, --file {filename.flac}\n"
+    "		    -O, --stdio\n"
     "		    -b, --bandwidth {rx_bandwidth}\n"
     "		    -v, --volume {amplitude or 'E'}\n"
     "		    -M, --mark {mark_freq}\n"
@@ -555,8 +556,8 @@ main( int argc, char*argv[] )
     /* validate the default system audio mechanism */
 #if !(USE_SNDIO || USE_PULSEAUDIO || USE_ALSA)
 # define _MINIMODEM_NO_SYSTEM_AUDIO
-# if !USE_SNDFILE
-#  error At least one of {USE_SNDIO,USE_PULSEAUDIO,USE_ALSA,USE_SNDFILE} must be enabled!
+# if !(USE_SNDFILE || USE_STDIO)
+#  error At least one of {USE_SNDIO,USE_PULSEAUDIO,USE_ALSA,USE_SNDFILE,USE_STDIO} must be enabled!
 # endif
 #endif
 
@@ -607,6 +608,7 @@ main( int argc, char*argv[] )
 	    { "usos",  		1, 0, 'u' },
 	    { "msb-first",	0, 0, MINIMODEM_OPT_MSBFIRST },
 	    { "file",		1, 0, 'f' },
+	    { "stdio",		0, 0, 'O' },
 	    { "bandwidth",	1, 0, 'b' },
 	    { "volume",		1, 0, 'v' },
 	    { "mark",		1, 0, 'M' },
@@ -631,7 +633,7 @@ main( int argc, char*argv[] )
 	    { "tx-carrier",      0, 0, MINIMODEM_OPT_TXCARRIER },
 	    { 0 }
 	};
-	c = getopt_long(argc, argv, "Vtrc:l:ai875u:f:b:v:M:S:T:qs::A::R:",
+	c = getopt_long(argc, argv, "Vtrc:l:ai875u:f:Ob:v:M:S:T:qs::A::R:",
 		long_options, &option_index);
 	if ( c == -1 )
 	    break;
@@ -664,6 +666,16 @@ main( int argc, char*argv[] )
 	    case 'f':
 			filename = optarg;
 			break;
+	    case 'O':
+#if USE_STDIO
+			sa_backend = SA_BACKEND_STDIO;
+                        // Apparently the receiver wants floats, so I'mma just output floats
+                        sample_format = SA_SAMPLE_FORMAT_FLOAT;
+#else
+			fprintf(stderr, "E: This build of minimodem was configured without stdio support.\n");
+			exit(1);
+#endif
+			break;
 	    case '8':
 			bfsk_n_data_bits = 8;
 			break;

src/simpleaudio-stdio.c

@@ -0,0 +1,129 @@
+/*
+ * simpleaudio-stdfile.c
+ *
+ * Copyright (C) 2011-2020 Kamal Mostafa <[email protected]>
+ *
+ *  This program 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 of the License, or
+ *  (at your option) any later version.
+ *
+ *  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 General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#if USE_STDIO
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+
+#include "simpleaudio.h"
+#include "simpleaudio_internal.h"
+
+
+/*
+ * stdio backend for simpleaudio
+ */
+
+static ssize_t
+sa_stdio_read( simpleaudio *sa, void *buf, size_t nframes )
+{
+    int n;
+    switch ( sa->format ) {
+	case SA_SAMPLE_FORMAT_FLOAT:
+                n = fread(buf, 4, nframes, stdin);
+		break;
+	case SA_SAMPLE_FORMAT_S16:
+                n = fread(buf, 2, nframes, stdin);
+		break;
+	default:
+		assert(0);
+		break;
+    }
+    if ( n < 0 ) {
+	fprintf(stderr, "read error");
+	return -1;
+    }
+
+    if ( sa->rxnoise != 0.0f ) {
+	int i;
+	float *fbuf = buf;
+	float f = sa->rxnoise * 2;
+	for ( i=0; i<nframes; i++ )
+	    fbuf[i] += (rand()/RAND_MAX - 0.5f) * f;
+    }
+
+    // fprintf(stderr, "sf_read: nframes=%ld n=%d\n", nframes, n);
+    return n;
+}
+
+static ssize_t
+sa_stdio_write( simpleaudio *sa, void *buf, size_t nframes )
+{
+    // fprintf(stderr, "sf_write: nframes=%ld\n", nframes);
+    int n;
+    switch ( sa->format ) {
+	case SA_SAMPLE_FORMAT_FLOAT:
+                n = fwrite(buf, 4, nframes, stdout);
+		break;
+	case SA_SAMPLE_FORMAT_S16:
+                n = fwrite(buf, 2, nframes, stdout);
+		break;
+	default:
+		assert(0);
+		break;
+    }
+    if ( n < 0 ) {
+	fprintf(stderr, "write error");
+	return -1;
+    }
+    return n;
+}
+
+
+static void
+sa_stdio_close( simpleaudio *sa )
+{
+    // This is probably safe even when reading, right?
+    fflush(stdout);
+}
+
+static int
+sa_stdio_open_stream(
+		simpleaudio *sa,
+		const char *backend_device,
+		sa_direction_t sa_stream_direction,
+		sa_format_t sa_format,
+		unsigned int rate, unsigned int channels,
+		char *app_name, char *stream_name )
+{
+    /* good or bad to override these? */
+    sa->rate = rate;
+    sa->channels = channels;
+
+    sa->backend_handle = NULL;
+    sa->backend_framesize = sa->channels * sa->samplesize; 
+
+    return 1;
+}
+
+
+const struct simpleaudio_backend simpleaudio_backend_stdio = {
+    sa_stdio_open_stream,
+    sa_stdio_read,
+    sa_stdio_write,
+    sa_stdio_close,
+};
+
+#endif /* USE_STDIO */

src/simpleaudio.c

@@ -74,6 +74,12 @@ simpleaudio_open_stream(
 	    break;
 #endif
 
+#if USE_STDIO
+	case SA_BACKEND_STDIO:
+	    sa->backend = &simpleaudio_backend_stdio;
+	    break;
+#endif
+
 #if USE_BENCHMARKS
 	case SA_BACKEND_BENCHMARK:
 	    sa->backend = &simpleaudio_backend_benchmark;

src/simpleaudio.h

@@ -35,6 +35,7 @@ typedef struct simpleaudio simpleaudio;
 typedef enum {
 	SA_BACKEND_SYSDEFAULT=0,
 	SA_BACKEND_FILE,
+	SA_BACKEND_STDIO,
 	SA_BACKEND_BENCHMARK,
 	SA_BACKEND_ALSA,
 	SA_BACKEND_PULSEAUDIO,

src/simpleaudio_internal.h

@@ -61,6 +61,7 @@ struct simpleaudio_backend {
 
 extern const struct simpleaudio_backend simpleaudio_backend_benchmark;
 extern const struct simpleaudio_backend simpleaudio_backend_sndfile;
+extern const struct simpleaudio_backend simpleaudio_backend_stdio;
 extern const struct simpleaudio_backend simpleaudio_backend_alsa;
 extern const struct simpleaudio_backend simpleaudio_backend_pulseaudio;
 extern const struct simpleaudio_backend simpleaudio_backend_sndio;