--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/decoders/midi.c	Wed Oct 03 20:17:13 2001 +0000
@@ -0,0 +1,265 @@
+/*
+ * SDL_sound -- An abstract sound format decoding API.
+ * Copyright (C) 2001  Ryan C. Gordon.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+/*
+ * MIDI decoder for SDL_sound, using TiMidity.
+ *
+ * This is a rough, proof-of-concept implementation. A number of things need
+ *  to be fixed or at the very least looked at:
+ *
+ * - I have only tested this with TiMidity++. Does TiMidity use the same
+ *   command-line options?
+ * - No attempt is made to ensure that the input really is MIDI. Eek. Does
+ *   anyone here know how to recognize MIDI?
+ * - Error handling is a joke.
+ * - Did I make any stupid errors in the process communication?
+ * - TiMidity++ spews a number of messages (to stderr?) which should be
+ *   silenced eventually.
+ * - This has to be the least portable decoder that has ever been written.
+ * - Etc.
+ *
+ * Oh, and the whole thing should be rewritten as a generic "send data to
+ *  external decoder" thing so this version should either be scrapped or
+ *  cannibalized for ideas. :-)
+ *
+ * Please see the file LICENSE in the source's root directory.
+ *
+ *  This file written by Torbjörn Andersson. (d91tan@Update.UU.SE)
+ */
+
+#if HAVE_CONFIG_H
+#  include <config.h>
+#endif
+
+#ifdef SOUND_SUPPORTS_MIDI
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#include <unistd.h>
+#include <signal.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include "SDL_sound.h"
+
+#define __SDL_SOUND_INTERNAL__
+#include "SDL_sound_internal.h"
+
+
+static int MIDI_init(void);
+static void MIDI_quit(void);
+static int MIDI_open(Sound_Sample *sample, const char *ext);
+static void MIDI_close(Sound_Sample *sample);
+static Uint32 MIDI_read(Sound_Sample *sample);
+
+const Sound_DecoderFunctions __Sound_DecoderFunctions_MIDI =
+{
+    {
+        "MIDI",
+        "MIDI music through the TiMidity MIDI to WAVE converter",
+        "Torbjörn Andersson <d91tan@Update.UU.SE>",
+        "http://www.goice.co.jp/member/mo/timidity/"
+    },
+
+    MIDI_init,       /* init() method       */
+    MIDI_quit,       /* quit() method       */
+    MIDI_open,       /* open() method       */
+    MIDI_close,      /* close() method       */
+    MIDI_read        /* read() method       */
+};
+
+    /* this is what we store in our internal->decoder_private field... */
+typedef struct
+{
+    int fd_audio;
+} midi_t;
+
+
+static void sig_pipe(int signo)
+{
+    signal(signo, sig_pipe);
+} /* sig_pipe */
+
+
+static int MIDI_init(void)
+{
+    if (signal(SIGPIPE, sig_pipe) == SIG_ERR)
+    {
+        Sound_SetError("MIDI: Could not set up SIGPIPE signal handler.");
+        return(0);
+    } /* if */
+    return(1);
+} /* MIDI_init */
+
+
+static void MIDI_quit(void)
+{
+    /* it's a no-op. */
+} /* MIDI_quit */
+
+
+static int MIDI_open(Sound_Sample *sample, const char *ext)
+{
+    Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque;
+    SDL_RWops *rw = internal->rw;
+    midi_t *m;
+    Uint8 buf[BUFSIZ];
+    ssize_t retval;
+    int fd1[2];
+    int fd2[2];
+    pid_t pid;
+
+        /* TiMidity does all the conversions we need. */
+    memcpy(&sample->actual, &sample->desired, sizeof (Sound_AudioInfo));
+    sample->flags = SOUND_SAMPLEFLAG_NONE;
+
+    if (pipe(fd1) < 0 || pipe(fd2) < 0)
+    {
+        Sound_SetError("MIDI: Pipe error.");
+        return(0);
+    } /* if */
+
+    pid = fork();
+    if (pid < 0)
+    {
+        Sound_SetError("MIDI: Fork error.");
+        return(0);
+    } /* if */
+
+    if (pid == 0)
+    {
+        /* child */
+        char arg_freq[10];   /* !!! FIXME: Large enough? */
+        char arg_format[10];
+        char *arg_list[] =
+            { "timidity", "-s", NULL, NULL, "-o", "-", "-", NULL };
+
+        arg_list[2] = arg_freq;
+        arg_list[3] = arg_format;
+
+        close(fd1[1]);
+        close(fd2[0]);
+
+            /* !!! FIXME: Errors should be propagated back to the parent */
+
+        if (fd1[0] != STDIN_FILENO)
+        {
+            if (dup2(fd1[0], STDIN_FILENO) != STDIN_FILENO)
+                return(0);
+            close(fd1[0]);
+        } /* if */
+
+        if (fd2[1] != STDOUT_FILENO)
+        {
+            if (dup2(fd2[1], STDOUT_FILENO) != STDOUT_FILENO)
+                return(0);
+            close(fd2[1]);
+        } /* if */
+
+            /* Construct command-line arguments matching the audio format */
+        sprintf(arg_freq, "%d", sample->actual.rate);
+        sprintf(arg_format, "-Or%c%c%cl",
+                (sample->actual.format & 0x0008) ? '8' : '1',
+                (sample->actual.format & 0x8000) ? 's' : 'u',
+                (sample->actual.channels == 1) ? 'M' : 'S');
+        if ((sample->actual.format & 0x0010) &&
+            (sample->actual.format & 0x7fff) != (AUDIO_S16SYS & 0x7fff))
+            strcat(arg_format, "x");
+
+        if (execvp("timidity", arg_list) < 0)
+            return(0);
+
+        SNDDBG(("MIDI: Is this line ever reached?"));
+        return(1);
+    } /* if */
+
+    /* parent */
+    close(fd1[0]);
+    close(fd2[1]);
+
+        /* Copy the entire file to the child process */
+    for (;;)
+    {
+        retval = SDL_RWread(internal->rw, buf, 1, BUFSIZ);
+        if (retval == 0)
+            break;
+
+        if (write(fd1[1], buf, retval) != retval)
+        {
+            Sound_SetError("MIDI: Could not send data to child process.");
+            return(0);
+        }
+    } /* for */
+
+    close(fd1[1]);
+
+    /* !!! FIXME: We still need some way of recognizing valid MIDI data */
+
+    m = (midi_t *) malloc(sizeof(midi_t));
+    BAIL_IF_MACRO(m == NULL, ERR_OUT_OF_MEMORY, 0);
+    internal->decoder_private = (void *) m;
+
+        /* This is where we'll read the converted audio data. */
+    m->fd_audio = fd2[0];
+
+    SNDDBG(("MIDI: Accepting data stream.\n"));
+    return(1); /* we'll handle this data. */
+} /* MIDI_open */
+
+
+static void MIDI_close(Sound_Sample *sample)
+{
+    Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque;
+
+    close(((midi_t *) internal->decoder_private)->fd_audio);
+    free(internal->decoder_private);
+} /* MIDI_close */
+
+
+static Uint32 MIDI_read(Sound_Sample *sample)
+{
+    ssize_t retval;
+    Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque;
+    midi_t *m = (midi_t *) internal->decoder_private;
+
+        /*
+         * We don't actually do any decoding, so we read the converted data
+         *  directly into the internal buffer.
+         */
+    retval = read(m->fd_audio, internal->buffer, internal->buffer_size);
+
+        /* Make sure the read went smoothly... */
+    if (retval == 0)
+        sample->flags |= SOUND_SAMPLEFLAG_EOF;
+
+    else if (retval == -1)
+        sample->flags |= SOUND_SAMPLEFLAG_ERROR;
+
+        /* (next call this EAGAIN may turn into an EOF or error.) */
+    else if (retval < internal->buffer_size)
+        sample->flags |= SOUND_SAMPLEFLAG_EAGAIN;
+
+    return(retval);
+} /* MIDI_read */
+
+#endif /* SOUND_SUPPORTS_MIDI */
+
+/* end of midi.c ... */
+