Imported Upstream version 4.2-build2006upstream/4.2-build2006upstream

1 files changed, 126 insertions, 0 deletions

diff --git a/tutorials/sndkit/tests/sweepdown.c b/tutorials/sndkit/tests/sweepdown.c
new file mode 100644
index 0000000..8006053
--- /dev/null
+++ b/tutorials/sndkit/tests/sweepdown.c
@@ -0,0 +1,126 @@
+/*
+ * Purpose: Plays a funny synthetic engine stop sound
+ * Copyright (C) 4Front Technologies, 2002-2004. Released under GPLv2/CDDL.
+ *
+ * Description:
+ * This program was supposed to do a frequency sweep down from sample_rate/2
+ * to 0 Hz. However due to some arithmetic problem the result was much more
+ * interesting.
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <soundcard.h>
+
+char *dspname = "/dev/dsp";
+
+int fd;
+
+#define SIN_STEPS	48
+static short sinebuf[48] = {
+  0, 4276, 8480, 12539, 16383, 19947, 23169, 25995,
+  28377, 30272, 31650, 32486, 32767, 32486, 31650, 30272,
+  28377, 25995, 23169, 19947, 16383, 12539, 8480, 4276,
+  0, -4276, -8480, -12539, -16383, -19947, -23169, -25995,
+  -28377, -30272, -31650, -32486, -32767, -32486, -31650, -30272,
+  -28377, -25995, -23169, -19947, -16383, -12539, -8480, -4276
+};
+
+#define F_SCALE (1000000)
+
+int phase = 0, freq = F_SCALE / 2;
+
+static void
+sweeper (int speed, int channels, int fragsize)
+{
+  short buf[4096], *p = buf;
+  int c, i, n, v, x;
+
+  fragsize /= 2 * channels;
+  speed /= 100;
+
+  for (i = 0; i < fragsize; i++)
+    {
+      x = (phase + F_SCALE / 2) / F_SCALE;
+      if (x < 0) x = 0;
+      v = sinebuf[x % SIN_STEPS] / 4;
+
+      phase = phase + freq * 480 / speed;
+
+      if (freq > 1000)
+	freq -= 3 * 480 / speed;
+      else
+	freq -= 1;
+
+      for (c = 0; c < channels; c++)
+	*p++ = v;
+
+      if (freq <= 0)
+	break;
+    }
+
+  write (fd, buf, i * 2 * channels);
+}
+
+int
+main (int argc, char *argv[])
+{
+  int bits, channels, speed, tmp;
+  int i, l;
+
+  if (argc == 2)
+    dspname = argv[1];
+
+
+  if ((fd = open (dspname, O_WRONLY, 0)) == -1)
+    {
+      perror (dspname);
+      exit (-1);
+    }
+
+  speed = 96000;
+  channels = 2;
+  bits = AFMT_S16_NE;
+
+  if (ioctl (fd, SNDCTL_DSP_CHANNELS, &channels) == -1)
+    {
+      perror ("SNDCTL_DSP_CHANNELS");
+      exit (-1);
+    }
+
+  if (ioctl (fd, SNDCTL_DSP_SETFMT, &bits) == -1)
+    {
+      perror ("SNDCTL_DSP_SETFMT");
+      exit (-1);
+    }
+
+  if (bits != AFMT_S16_NE)
+    {
+      fprintf (stderr,
+	       "Device %s doesn't support 16 bit (native endian) format\n",
+	       dspname);
+      exit (-1);
+    }
+
+  if (ioctl (fd, SNDCTL_DSP_SPEED, &speed) == -1)
+    {
+      perror ("SNDCTL_DSP_SPEED");
+      exit (-1);
+    }
+
+  if (ioctl (fd, SNDCTL_DSP_GETBLKSIZE, &tmp) == -1)
+    {
+      perror ("SNDCTL_DSP_GETBLKSIZE");
+      exit (-1);
+    }
+
+  printf ("Outputting sweep at %d Hz, %d channels, 16 bits\n", speed,
+	  channels);
+  printf ("Fragment size is %d\n", tmp);
+
+  while (freq > 0)
+    sweeper (speed, channels, tmp);
+
+  exit (0);
+}