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diff --git a/tutorials/sndkit/samples/mmap_duplex.c b/tutorials/sndkit/samples/mmap_duplex.c
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+/*
+ * Purpose: A simple sample program for doing dull duplex using mmap
+ *
+ * Description:
+ *
+ * This is a sample program for doing full duplex using mmap.
+ *
+ * Unfortunately this program doesn't work at this moment (under construction).
+ *
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/types.h>
+#include <sys/mman.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <soundcard.h>
+
+/*
+ * Note that the mmap approach bypasses the OSS drivers completely so you are
+ * on your own. You will need to write the application so that it
+ * can work with any sample rate or sample format one can imagine.
+ *
+ * We will try to use 48 kHz / 16 bits / stereo which is the most likely
+ * format supported by the consumer audio devices.
+ */
+#define SAMPLE_RATE 48000
+#define SAMPLE_FORMAT AFMT_S16_NE
+#define NUM_CHANNELS 2
+/*
+ * NOTICE!
+ *
+ * The mmap() feature is not supported by all devices. Using it will make
+ * the application to fail with some devices (professional ones in particular).
+ *
+ * When using the mmap mode it's very important to disable any format
+ * conversions done by OSS. This can be done by calling SNDCTL_DSP_COOKEDMODE
+ * _IMMEDIATELY_ after opening the device.
+ */
+
+int sample_rate, num_channels, sample_format;
+
+int
+main (int argc, char *argv[])
+{
+ int fd, sz, i, tmp, n, l, have_data = 0;
+
+/*
+ * /dev/dsp_mmap is the best default device. Another alternative is /dev/dsp
+ * but in some systems the user may want to use different devices with
+ * mmap applications than with the normal ones.
+ *
+ * /dev/dsp_mmap will not be present in pre OSS 4.0 systems. The application
+ * may automatically try to open /dev/dsp if /dev/dsp_mmap is missing.
+ * Another approach is asking the user to create /dev/dsp_mmap.
+ *
+ * ln -s /dev/dsp /dev/dsp_mmap
+ *
+ * It's recommended that there is some method for configuring or selecting
+ * the audio device (such as a command line option or an environment
+ * variable.
+ */
+ char *audio_dev = "/dev/dsp_mmap";
+
+ struct buffmem_desc imemd, omemd;
+ caddr_t buf;
+
+ char *ip, *op;
+
+ struct audio_buf_info info;
+
+ int frag = 0x00200008; /* 32 fragments of 2^8=256 bytes */
+
+ fd_set reads, writes;
+
+/*
+ * Getting the device name to open. First the command line method
+ * (simplified).
+ */
+
+ if (argc >= 2)
+ {
+ audio_dev = argv[1];
+ }
+ else
+ {
+ /*
+ * No device given on command line. Try to see if an environment
+ * variable is set.
+ *
+ * We will use MYAPP_AUDIODEV as the variable name. Replace the
+ * MYAPP_ prefix with your application name.
+ */
+
+ char *p;
+
+ if ((p = getenv ("MYAPP_AUDIODEV")) != NULL)
+ audio_dev = p;
+ }
+
+ if ((fd = open (audio_dev, O_RDWR, 0)) == -1)
+ {
+ perror (audio_dev);
+ exit (-1);
+ }
+ /*
+ * Disable cooked mode to permit mmap() with some devices.
+ * Don't do any error checking since usually this call will fail.
+ * There is no need to care about the return value.
+ */
+ tmp = 0;
+ ioctl (fd, SNDCTL_DSP_COOKEDMODE, &tmp); /* Don't check the error return */
+
+ ioctl (fd, SNDCTL_DSP_SETFRAGMENT, &frag); /* No error checking needed */
+
+/*
+ * Set the sample format. AFMT_S16_NE is best because it is supported by
+ * practically all devices. Also it equals to the "short" data type.
+ */
+
+ sample_format = SAMPLE_FORMAT;
+ if (ioctl (fd, SNDCTL_DSP_SETFMT, &sample_format) == -1)
+ { /* Something really fatal occurred. */
+ perror ("SNDCTL_DSP_SETFMT");
+ exit (-1);
+ }
+
+/*
+ * Check that we can support the returned sample format.
+ */
+ switch (sample_format)
+ {
+ case AFMT_S16_NE:
+ /*
+ * Everything is OK. The sample format equals to 16 bit native
+ * integer (short in C/C++) so we do not need to do any
+ * format conversions.
+ */
+ break;
+
+#if 0
+/*
+ * We do not support any other formats. However you must be prepared to do
+ * so. Please take a look at the formats section of the OSS API
+ * manual.
+ *
+ * Here are the most common other formats.
+ */
+
+ case AFMT_S16_OE:
+ /*
+ * 16 bits but with alien endianess. We can use short as the data type
+ * but the samples must be "byte swapped" prior writing them to
+ * the device.
+ */
+ break;
+
+ case AFMT_U8:
+ /* 8 bits unsigned format (unsigned char). Note that signed
+ * 16 bit samples can be converted to this format by
+ * doing u8_sample = (s16_ne_sample >> 8) - 128.
+ */
+ break;
+
+ case AFMT_S24_NE:
+ case AFMT_S24_OE:
+ case AFMT_S32_NE:
+ case AFMT_S32_OE:
+ /* Please see the formats section of the OSS API
+ * manual.
+ */
+
+#endif
+
+ default:
+ fprintf (stderr, "The device doesn't support the requested format\n");
+ fprintf (stderr, "0x%08x != 0x%08x\n", tmp, SAMPLE_FORMAT);
+ exit (-1);
+ }
+
+/*
+ * Set up the number of channels.
+ * This program will automatically support any number of channels by
+ * writing the same sample value to each of the channels (mono).
+ *
+ * Equally well stereo samples can be mixed for a 1 channel
+ * device by summing the channel values together. Stereo samples
+ * can be played with multi channel devices by setting the remaining
+ * channel samples to a silent value (0 with signed formats).
+ */
+
+ num_channels = NUM_CHANNELS;
+ if (ioctl (fd, SNDCTL_DSP_CHANNELS, &num_channels) == -1)
+ {
+ perror ("SNDCTL_DSP_CHANNELS");
+ exit (-1);
+ }
+
+/*
+ * Set the sample rate.
+ */
+ tmp = SAMPLE_RATE;
+ if (ioctl (fd, SNDCTL_DSP_SPEED, &tmp) == -1)
+ {
+ perror ("SNDCTL_DSP_SPEED");
+ exit (-1);
+ }
+
+ if (tmp != SAMPLE_RATE)
+ {
+ /*
+ * In some cases the device is not capable to support exactly
+ * the requested sampling rate.
+ *
+ * We will tolerate a 5% error in between the requested and
+ * granted sampling rates.
+ *
+ * If the error is larger then we cannot continue.
+ *
+ * NOTE! Applications written for the mass market must be prepared
+ * to support every possible sampling rate locally.
+ */
+ int v;
+
+ v = abs (tmp - SAMPLE_RATE);
+
+ if (v > ((SAMPLE_RATE * 5) / 100))
+ {
+ fprintf (stderr,
+ "The device doesn't support sampling rate of %d Hz.\n",
+ SAMPLE_RATE);
+ fprintf (stderr, "The nearest rate it supports is %d Hz\n", tmp);
+ exit (-1);
+ }
+ }
+
+ if (ioctl (fd, SNDCTL_DSP_GETISPACE, &info) == -1)
+ {
+ perror ("GETISPACE");
+ exit (-1);
+ }
+
+ sz = info.fragstotal * info.fragsize;
+
+ if ((buf =
+ mmap (NULL, sz, PROT_READ, MAP_FILE | MAP_PRIVATE, fd,
+ 0)) == (caddr_t) - 1)
+ {
+ perror ("mmap (read)");
+ exit (-1);
+ }
+ printf ("mmap (in) returned %08x\n", buf);
+ ip = buf;
+
+ if ((buf =
+ mmap (NULL, sz, PROT_WRITE, MAP_FILE | MAP_PRIVATE, fd,
+ 0)) == (caddr_t) - 1)
+ {
+ perror ("mmap (write)");
+ exit (-1);
+ }
+ printf ("mmap (out) returned %08x\n", buf);
+ op = buf;
+
+/*
+ * Prepare for launch. Set the trigger bits to 0
+ */
+ tmp = 0;
+ ioctl (fd, SNDCTL_DSP_GETTRIGGER, &tmp);
+ printf ("Trigger was %08x\n", tmp);
+
+ tmp = PCM_ENABLE_OUTPUT;
+ ioctl (fd, SNDCTL_DSP_SETTRIGGER, &tmp);
+ printf ("Trigger set to %08x\n", tmp);
+
+ for (i = 0; i < sz; i++)
+ op[i] = 0x00;
+
+ while (1)
+ {
+ struct timeval time;
+
+ FD_ZERO (&reads);
+ FD_ZERO (&writes);
+
+ /* FD_SET(fd, &writes); */
+ FD_SET (fd, &reads);
+
+ time.tv_sec = 1;
+ time.tv_usec = 0;
+ if (select (fd + 1, &reads, &writes, NULL, &time) == -1)
+ {
+ perror ("select");
+ exit (-1);
+ }
+
+ if (FD_ISSET (fd, &reads))
+ {
+ count_info count, ocount;
+ int l, p;
+
+ if (ioctl (fd, SNDCTL_DSP_GETIPTR, &count) == -1)
+ perror ("GETIPTR");
+
+ if (ioctl (fd, SNDCTL_DSP_GETOPTR, &ocount) == -1)
+ perror ("GETOPTR");
+
+ printf ("read(%08x/%08x/%d)\n", count.bytes, count.ptr,
+ count.blocks);
+ printf ("write(%08x/%08x/%d)\n", ocount.bytes, ocount.ptr,
+ ocount.blocks);
+
+ l = count.ptr;
+ p = ocount.ptr;
+
+ if (l > (sz - ocount.ptr))
+ l = sz - ocount.ptr;
+
+ for (i = 0; i < l; i++)
+ op[i + p] = ip[i];
+ }
+
+ if (FD_ISSET (fd, &writes))
+ {
+ printf ("write()\n");
+ have_data = 0;
+ }
+ }
+
+ exit (0);
+}
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