m

Signed-off-by: Mattias Andrée <maandree@member.fsf.org>

1 files changed, 503 insertions, 0 deletions

diff --git a/src/fodtmf-send.c b/src/fodtmf-send.c
new file mode 100644
index 0000000..b841e1f
--- /dev/null
+++ b/src/fodtmf-send.c
@@ -0,0 +1,503 @@
+/**
+ * Copyright © 2015  Mattias Andrée (maandree@member.fsf.org)
+ * 
+ * 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/>.
+ */
+#include "common.h"
+
+#include <stdio.h>
+#include <stdint.h>
+#include <signal.h>
+#include <errno.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <alloca.h>
+#include <getopt.h>
+#include <math.h> /* -lm */
+#include <alsa/asoundlib.h> /* dep: alsa-lib (pkg-config alsa) */
+
+
+
+#define UTYPE   uint32_t
+#define SMIN    INT32_MIN
+#define SMAX    INT32_MAX
+#define FORMAT  SND_PCM_FORMAT_U32
+
+#define SAMPLE_RATE  52000   /* Hz */
+#define DURATION     100     /* ms */ /* 100 ms → 10 Bd → 5 B/s */
+#define LATENCY      100000  /* µs */
+
+
+
+/**
+ * Number of samples per tone.
+ */
+#define N  (SAMPLE_RATE / 1000 * DURATION)
+
+
+
+/**
+ * The process's name.
+ */
+static const char* argv0;
+
+/**
+ * Audio descriptor.
+ */
+static snd_pcm_t* sound_handle = NULL;
+
+/**
+ * Audio playback buffer for each nibble.
+ */
+static UTYPE buffers[16][N];
+
+/**
+ * The number of parity tones in the hamming code.
+ */
+static int parity = 3;
+
+/**
+ * Whether to add an additional parity tone (of all
+ * data tones) in addition to those numerated by `parity`.
+ */
+static int use_extra_parity = 0;
+
+/**
+ * Whether to add redundancy frequencies in the tones.
+ */
+static int use_redundant_freq = 0;
+
+/**
+ * Frequencies multiple for the redundant frequencies.
+ */
+static double redundant_freq_mul = 0;
+
+/**
+ * Data buffer used for error correcting code support.
+ */
+static int* data;
+
+/**
+ * Code buffer used for error correcting code support.
+ */
+static int* code;
+
+/**
+ * The number elements that can be stored in `data`.
+ */
+static int data_n;
+
+/**
+ * The number elements that can be stored in `code`.
+ */
+static int code_n;
+
+/**
+ * File descriptor to write the audio to (with any metadata)
+ * rather than sending it to the audio subsystem.
+ * 
+ * This is available for developers of the receiver.
+ * It is not intend to be used for anything else.
+ */
+static int output_fd = -1;
+
+
+
+/**
+ * Use to accept signals, without doing anything
+ * about them, just be interrupted.
+ * 
+ * @param  signo  The received signal.
+ */
+static void signoop(int signo)
+{
+  (void) signo;
+}
+
+
+/**
+ * Get the tones used to transmit a nibble.
+ * 
+ * @param  nibble  The nibble.
+ * @param  low     Output parameter for the lower frequency.
+ * @param  high    Output parameter for the higher frequency.
+ */
+static void get_freq(int nibble, int* low, int* high)
+{
+  static const int LOW[]  = {  697,  770,  852,  941 };
+  static const int HIGH[] = { 1209, 1336, 1477, 1663 };
+  
+  *low  =  LOW[(nibble >> 0) & 0x03];
+  *high = HIGH[(nibble >> 2) & 0x03];
+}
+
+
+/**
+ * Initialise to before for each nibble.
+ */
+static void init_buffers(void)
+{
+#define GENERATE_TONE(tone)  sin(2 * M_PI * ((double)i / (SAMPLE_RATE / (tone))))
+  
+  size_t i;
+  UTYPE* buffer;
+  int j, low, high;
+  
+  for (j = 0; j < 16; j++)
+    {
+      buffer = buffers[j];
+      get_freq(j, &low, &high);
+      
+      if (use_redundant_freq)
+	for (i = 0; i < N; i++)
+	  buffer[i] = (GENERATE_TONE(low) +
+		       GENERATE_TONE(high) + 
+		       GENERATE_TONE(low * redundant_freq_mul) +
+		       GENERATE_TONE(high * redundant_freq_mul)) *
+	    (SMAX / 4) - SMIN;
+      else
+	for (i = 0; i < N; i++)
+	  buffer[i] = (GENERATE_TONE(low) + GENERATE_TONE(high)) *
+	    (SMAX / 2) - SMIN;
+    }
+}
+
+
+/**
+ * Transmit a nibble.
+ * 
+ * @param   n  The nibble.
+ * @return     0 on success, -1 on error.
+ */
+static int send_nibble(int n)
+{
+  UTYPE* buffer = buffers[n];
+  snd_pcm_sframes_t frames;
+  int r;
+  
+  if (output_fd >= 0)
+    {
+      char* buf = (char*)buffer;
+      size_t ptr = 0;
+      ssize_t wrote;
+      while (ptr < N)
+	{
+	  wrote = write(output_fd, buf + ptr, N - ptr);
+	  if (wrote < 0)
+	    return -1;
+	  ptr += (size_t)write;
+	}
+      return 0;
+    }
+  
+  r = frames = snd_pcm_writei(sound_handle, buffer, N);
+  if (frames < 0)
+    r = frames = snd_pcm_recover(sound_handle, r, 0 /* do not print error reason? */);
+  if (r < 0)
+    {
+      fprintf(stderr, "%s: snd_pcm_writei: %s\n", argv0, snd_strerror(r));
+      errno = 0;
+      return -1;
+    }
+  if ((r > 0) && ((size_t)r < N))
+    printf("%s: short write: expected %zu, wrote %zu\n", argv0, N, (size_t)frames);
+  
+  return 0;
+}
+
+
+/**
+ * Transmit a byte.
+ * 
+ * @param   c  The byte.
+ * @return     0 on success, -1 on error.
+ */
+static int send_byte(int c)
+{
+#ifdef DEBUG
+  fprintf(stderr, "%s: sending byte: %i\n", argv0, c);
+#endif
+  if (send_nibble((c >> 0) & 0x0F))  return -1;
+  if (send_nibble((c >> 4) & 0x0F))  return -1;
+  return 0;
+}
+
+
+/**
+ * Transmit a byte with error correcting code.
+ * 
+ * This function uses a buffer so that it can
+ * create an error correcting code. The bytes
+ * are not transmitted until this buffer has
+ * been filled.
+ * 
+ * @param   c  The byte, the negative of that byte (intended
+ *             only for `CHAR_END` and `CHAR_CANCEL`) to fill
+ *             the remained of the buffer with the byte.
+ *             Note that if a negative value is used, it is
+ *             no necessary that anything will happen.
+ * @return     0 on success, -1 on error.
+ */
+static int send_byte_with_ecc(int c)
+{
+  static int ptr = 0;
+  int i, j, d, p;
+  
+  if (parity < 2)
+    {
+      if (c < 0)
+	return 0;
+      if (send_byte(c))
+	return -1;
+      if (parity)
+	if (send_byte(c))
+	  return -1;
+      if (use_extra_parity)
+	if (send_byte(c))
+	  return -1;
+      return 0;
+    }
+  
+  /* Fill buffer. */
+  if (c < 0)
+    {
+      if (ptr > 0)
+	while (ptr < data_n)
+	  data[ptr++] = -c;
+    }
+  else
+    data[ptr++] = c;
+  
+  /* Is it full? */
+  if (ptr < data_n)
+    return 0;
+  ptr = 0;
+  
+  /* Hamming code. */
+  memset(code, 0, code_n * sizeof(*code));
+  for (i = 1, j = 0; i <= (1 << parity) - 1; i++)
+    {
+      if ((i & -i) == i)
+	continue;
+      for (d = i, p = 0; d; d >>= 1, p++)
+	if (d & 1)
+	  code[(1 << p) - 1] ^= data[j];
+      code[i - 1] = data[j];
+      j++;
+    }
+  if (use_extra_parity)
+    for (i = 0; i < data_n; i++)
+      code[(1 << parity) - 1] ^= data[i];
+  
+  /* Transmit. */
+  for (i = 0; i < code_n; i++)
+    if (send_byte(code[i]))
+      return -1;
+  
+  return 0;
+}
+
+
+/**
+ * Transmit a chunk of bytes.
+ * 
+ * @param   buf  The chunk to transmit.
+ * @param   n    The number of bytes in the chunk.
+ * @return       0 on success, -1 on failure.
+ */
+static int send_chunk(char* buf, size_t n)
+{
+  size_t i;
+  int c;
+  
+  for (i = 0; i < n; i++)
+    {
+      c = buf[i];
+      if ((c == CHAR_ESCAPE) || (c == CHAR_CANCEL) || (c == CHAR_END))
+	if (send_byte_with_ecc(CHAR_ESCAPE))
+	  goto qfile;
+      if (send_byte_with_ecc(c))
+	goto qfile;
+    }
+  
+  return 0;
+ qfile:
+  errno = 0;
+ fail:
+  return -1;
+}
+
+
+/**
+ * Read all input from stdin and transmit it as it is being read.
+ * 
+ * @return  0 on success, -1 on failure.
+ */
+static int send_file(void)
+{
+  char buf[1024];
+  ssize_t n;
+  
+  for (;;)
+    {
+      n = read(STDIN_FILENO, buf, sizeof(buf));
+      if (n < 0)   goto fail;
+      if (n == 0)  break;
+      if (send_chunk(buf, (size_t)n))
+	goto fail;
+    }
+  
+  return 0;
+ fail:
+  return -1;
+}
+
+
+/**
+ * Read all input from stdin, and then transmit it.
+ * 
+ * @return  0 on success, -1 on failure.
+ */
+static int send_term(void)
+{
+  char* buf = NULL;
+  size_t size = 0;
+  size_t ptr = 0;
+  ssize_t n;
+  void* new;
+  int saved_errno;
+  
+  for (;;)
+    {
+      if (ptr == size)
+	{
+	  size = size ? (size << 1) : 128;
+	  new = realloc(buf, size);
+	  if (new == NULL)
+	    goto fail;
+	  buf = new;
+	}
+      n = read(STDIN_FILENO, buf + ptr, size - ptr);
+      if (n < 0)   goto fail;
+      if (n == 0)  break;
+      ptr += (size_t)n;
+    }
+  if (send_chunk(buf, ptr))
+    goto fail;
+  
+  return 0;
+ fail:
+  saved_errno = errno;
+  free(buf);
+  errno = saved_errno;
+  return -1;
+}
+
+
+/**
+ * Transmit a file over audio.
+ * 
+ * @param   argc  The number of elements in `argv`.
+ * @param   argv  Command line arguments.
+ * @return        0 on success, 1 on failure.
+ */
+int main(int argc, char* argv[])
+{
+  struct sigaction act;
+  int r, rc = 1;
+  
+  /* Parse command line. */
+  argv0 = argc ? argv[0] : "";
+  for (;;)
+    {
+      r = getopt (argc, argv, "f:pr:o:");
+      if (r == -1)
+	break;
+      else if (r == 'f')  use_redundant_freq = 1, redundant_freq_mul = atof(optarg);
+      else if (r == 'p')  use_extra_parity = 1;
+      else if (r == 'r')  parity = atoi(optarg);
+      else if (r == 'o')  output_fd = atoi(optarg);
+      else if (r != '?')
+	abort();
+    }
+  
+  /* Set up signal handling. */
+  siginterrupt(SIGTERM, 1);
+  siginterrupt(SIGQUIT, 1);
+  siginterrupt(SIGINT, 1);
+  siginterrupt(SIGHUP, 1);
+  sigemptyset(&(act.sa_mask));
+  act.sa_handler = signoop;
+  act.sa_flags   = 0;
+  sigaction(SIGTERM, &act, NULL);
+  sigaction(SIGQUIT, &act, NULL);
+  sigaction(SIGHUP, &act, NULL);
+  sigprocmask(SIG_SETMASK, &(act.sa_mask), NULL);
+  
+  /* Generate the tones to play. */
+  init_buffers();
+  /* Generate buffers for error correcting code. */
+  data_n = (1 << parity) - parity - 1;
+  code_n = (1 << parity) - 1 + use_extra_parity;
+  data = alloca(data_n * sizeof(*data));
+  code = alloca(code_n * sizeof(*code));
+  
+  /* Set up audio. */
+  if (output_fd >= 0)
+    goto no_audio;
+  r = snd_pcm_open(&sound_handle, "default", SND_PCM_STREAM_PLAYBACK, 0);
+  if (r < 0)
+    return fprintf(stderr, "%s: snd_pcm_open: %s\n", *argv, snd_strerror(r)), 1;
+  if (sound_handle == NULL)
+    perror("snd_pcm_open");
+  /* Configure audio. */
+  r = snd_pcm_set_params(sound_handle, FORMAT, SND_PCM_ACCESS_RW_INTERLEAVED, 1 /* channels */,
+			 SAMPLE_RATE, 1 /* allow resampling? */, LATENCY);
+  if (r < 0)
+    return fprintf(stderr, "%s: snd_pcm_set_params: %s\n", *argv, snd_strerror(r)), 1;
+ no_audio:
+  
+  /* Send message. */
+  if (isatty(STDIN_FILENO))
+    {
+      if (send_term())
+	goto fail;
+    }
+  else
+    if (send_file())
+      goto fail;
+  
+  /* Mark end of transmission. */
+  if (send_byte_with_ecc(CHAR_END))   goto cleanup;
+  if (send_byte_with_ecc(-CHAR_END))  goto cleanup;
+  
+  /* Done! */
+  rc = 0;
+  goto cleanup;
+ fail:
+  if (errno)
+    perror(argv0);
+ cleanup:
+  if (output_fd >= 0)
+    snd_pcm_close(sound_handle);
+  /* Mark aborted transmission. */
+  if (rc)
+    {
+      send_byte_with_ecc(CHAR_CANCEL);
+      send_byte_with_ecc(-CHAR_CANCEL);
+    }
+  return rc;
+}
+