--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/decoders/shn.c	Tue Sep 25 22:43:09 2001 +0000
@@ -0,0 +1,215 @@
+/*
+ * 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
+ */
+
+/*
+ * Shorten decoder for SDL_sound.
+ *
+ * This driver handles Shorten-compressed waveforms. Despite the fact that
+ *  SHNs are generally used in online trading communities, they tend to be
+ *  much bigger than MP3s. If an MP3 crunches the waveform to 10-20 percent
+ *  of its original size, SHNs only go to about 50-60%. Why do the Phish fans
+ *  of the world use this format then? Rabid music traders appreciate the
+ *  sound quality; SHNs, unlike MP3s, do not throw away any part of the
+ *  waveform. Yes, there are people that notice this, and further more, they
+ *  demand it...and if they can't get a good transfer of those larger files
+ *  over the 'net, they haven't underestimated the bandwidth of CDs travelling
+ *  the world through the postal system.
+ *
+ * Shorten homepage: http://www.softsound.com/Shorten.html
+ *
+ * The Shorten format was gleaned from the shorten codebase, by Tony
+ *  Robinson and SoftSound Limited, but none of their code was used here.
+ *
+ * Please see the file LICENSE in the source's root directory.
+ *
+ *  This file written by Ryan C. Gordon. (icculus@clutteredmind.org)
+ */
+
+#if (defined SOUND_SUPPORTS_SHN)
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#include "SDL_sound.h"
+
+#define __SDL_SOUND_INTERNAL__
+#include "SDL_sound_internal.h"
+
+static int SHN_init(void);
+static void SHN_quit(void);
+static int SHN_open(Sound_Sample *sample, const char *ext);
+static void SHN_close(Sound_Sample *sample);
+static Uint32 SHN_read(Sound_Sample *sample);
+
+const Sound_DecoderFunctions __Sound_DecoderFunctions_SHN =
+{
+    {
+        "SHN",
+        "Shorten-compressed audio data",
+        "Ryan C. Gordon <icculus@clutteredmind.org>",
+        "http://www.icculus.org/SDL_sound/"
+    },
+
+    SHN_init,       /* init() method       */
+    SHN_quit,       /* quit() method       */
+    SHN_open,       /* open() method       */
+    SHN_close,      /* close() method       */
+    SHN_read        /* read() method       */
+};
+
+
+static int SHN_init(void)
+{
+    return(1);  /* initialization always successful. */
+} /* SHN_init */
+
+
+static void SHN_quit(void)
+{
+    /* it's a no-op. */
+} /* SHN_quit */
+
+
+static Uint32 mask_table[] =
+{
+    0x00000000, 0x00000001, 0x00000003, 0x00000007, 0x0000000F, 0x0000001F,
+    0x0000003F, 0x0000007F, 0x000000FF, 0x000001FF, 0x000003FF, 0x000007FF,
+    0x00000FFF, 0x00001FFF, 0x00003FFF, 0x00007FFF, 0x0000FFFF, 0x0001FFFF,
+    0x0003FFFF, 0x0007FFFF, 0x000FFFFF, 0x001FFFFF, 0x003FFFFF, 0x007FFFFF,
+    0x00FFFFFF, 0x01FFFFFF, 0x03FFFFFF, 0x07FFFFFF, 0x0FFFFFFF, 0x1FFFFFFF,
+    0x3FFFFFFF, 0x7FFFFFFF, 0xFFFFFFFF
+};
+
+
+#define MAGIC_NUM 0x676B6A61   /* looks like "ajkg" as chars. */
+
+/*
+ * Look through the whole file for a SHN magic number. This is costly, so
+ *  it should only be done if the user SWEARS they have a Shorten stream...
+ */
+static inline int extended_shn_magic_search(Sound_Sample *sample)
+{
+    SDL_RWops *rw = ((Sound_SampleInternal *) sample->opaque)->rw;
+    Uint32 word = 0;
+    Uint8 ch;
+
+    while (1)
+    {
+        BAIL_IF_MACRO(SDL_RWread(rw, &ch, sizeof (ch), 1) != 1, NULL, -1);
+        word = ((word << 8) & 0xFFFFFF00) | ch;
+        if (SDL_SwapLE32(word) == MAGIC_NUM)
+        {
+            BAIL_IF_MACRO(SDL_RWread(rw, &ch, sizeof (ch), 1) != 1, NULL, -1);
+            return((int) ch);
+        } /* if */
+    } /* while */
+
+    return((int) ch);
+} /* extended_shn_magic_search */
+
+
+/* look for the magic number in the RWops and see what kind of file this is. */
+static inline int determine_shn_version(Sound_Sample *sample)
+{
+    SDL_RWops *rw = ((Sound_SampleInternal *) sample->opaque)->rw;
+    Uint32 magic;
+    Uint8 ch;
+
+    /*
+     * Apparently the magic number can start at any byte offset in the file,
+     *  and we should just discard prior data, but I'm going to restrict it
+     *  to offset zero for now, so we don't chug down every file that might
+     *  happen to pass through here. If the extension is explicitly "SHN", we
+     *  check the whole stream, though.
+     */
+
+    if (__Sound_strcasecmp(ext, "shn") == 0)
+        return(extended_shn_magic_search(sample);
+
+    BAIL_IF_MACRO(SDL_RWread(rw, &magic, sizeof (magic), 1) != 1, NULL, -1);
+    BAIL_IF_MACRO(SDL_SwapLE32(magic) != MAGIC_NUM, "SHN: Not a SHN file", -1);
+    BAIL_IF_MACRO(SDL_RWread(rw, &ch, sizeof (ch), 1) != 1, NULL, -1);
+    BAIL_IF_MACRO(ch > 3, "SHN: Unsupported file version", -1);
+
+    return((int) ch);
+} /* determine_shn_version */
+
+
+static int SHN_open(Sound_Sample *sample, const char *ext)
+{
+    Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque;
+    SDL_RWops *rw = internal->rw;
+    int shn_version = determine_shn_version(sample, ext);
+    int mean = MEAN_VERSION2;
+
+    BAIL_IF_MACRO(shn_version == -1, NULL, 0);
+    if (shn_version < 2)  /* downgrade? */
+        mean = MEAN_VERSION0;
+
+
+
+    SNDDBG(("SHN: Accepting data stream.\n"));
+    set up sample->actual;
+    sample->flags = SOUND_SAMPLEFLAG_NONE;
+    return(1); /* we'll handle this data. */
+} /* SHN_open */
+
+
+static void SHN_close(Sound_Sample *sample)
+{
+    Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque;
+    clean up anything you put into internal->decoder_private;
+} /* SHN_close */
+
+
+static Uint32 SHN_read(Sound_Sample *sample)
+{
+    Uint32 retval;
+    Sound_SampleInternal *internal = (Sound_SampleInternal *) sample->opaque;
+
+        /*
+         * We don't actually do any decoding, so we read the fmt data
+         *  directly into the internal buffer...
+         */
+    retval = SDL_RWread(internal->rw, internal->buffer,
+                        1, internal->buffer_size);
+
+    (or whatever. Do some decoding here...)
+
+        /* 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;
+
+    (or whatever. retval == number of bytes you put in internal->buffer).
+
+    return(retval);
+} /* SHN_read */
+
+#endif  /* defined SOUND_SUPPORTS_SHN */
+
+/* end of shn.c ... */
+