/**
 * OpenAL cross platform audio library
 * Copyright (C) 1999-2007 by authors.
 * This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Library General Public
 *  License as published by the Free Software Foundation; either
 *  version 2 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
 *  Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library 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.
 * Or go to http://www.gnu.org/copyleft/lgpl.html
 */

#define _CRT_SECURE_NO_DEPRECATE // get rid of sprintf security warnings on VS2005

#include "config.h"

#include <stdlib.h>
#include <stdio.h>
#include <assert.h>
#include "alMain.h"
#include "AL/al.h"
#include "AL/alc.h"
#include "alError.h"
#include "alBuffer.h"
#include "alThunk.h"


static void LoadData(ALbuffer *ALBuf, const ALubyte *data, ALsizei size, ALuint freq, ALenum OrigFormat, ALenum NewFormat);
static void ConvertData(ALshort *dst, const ALvoid *src, ALint origBytes, ALsizei len);
static void ConvertDataRear(ALshort *dst, const ALvoid *src, ALint origBytes, ALsizei len);
static void ConvertDataIMA4(ALshort *dst, const ALvoid *src, ALint origChans, ALsizei len);

/*
 *  AL Buffer Functions
 *
 *  AL Buffers are shared amoung Contexts, so we store the list of generated Buffers
 *  as a global variable in this module.   (A valid context is not required to make
 *  AL Buffer function calls
 *
 */

/*
* Global Variables
*/

static ALbuffer *g_pBuffers = NULL;          // Linked List of Buffers
static ALuint    g_uiBufferCount = 0;        // Buffer Count

static const long g_IMAStep_size[89]={            // IMA ADPCM Stepsize table
       7,    8,    9,   10,   11,   12,   13,   14,   16,   17,   19,   21,   23,   25,   28,   31,
      34,   37,   41,   45,   50,   55,   60,   66,   73,   80,   88,   97,  107,  118,  130,  143,
     157,  173,  190,  209,  230,  253,  279,  307,  337,  371,  408,  449,  494,  544,  598,  658,
     724,  796,  876,  963, 1060, 1166, 1282, 1411, 1552, 1707, 1878, 2066, 2272, 2499, 2749, 3024,
    3327, 3660, 4026, 4428, 4871, 5358, 5894, 6484, 7132, 7845, 8630, 9493,10442,11487,12635,13899,
   15289,16818,18500,20350,22358,24633,27086,29794,32767
};

static const long g_IMACodeword_4[16]={            // IMA4 ADPCM Codeword decode table
    1, 3, 5, 7, 9, 11, 13, 15,
   -1,-3,-5,-7,-9,-11,-13,-15,
};

static const long g_IMAIndex_adjust_4[16]={        // IMA4 ADPCM Step index adjust decode table
   -1,-1,-1,-1, 2, 4, 6, 8,
   -1,-1,-1,-1, 2, 4, 6, 8
};

/*
*    alGenBuffers(ALsizei n, ALuint *puiBuffers)
*
*    Generates n AL Buffers, and stores the Buffers Names in the array pointed to by puiBuffers
*/
ALAPI ALvoid ALAPIENTRY alGenBuffers(ALsizei n,ALuint *puiBuffers)
{
    ALCcontext *Context;
    ALsizei i=0;

    Context = alcGetCurrentContext();
    SuspendContext(Context);

    // Check that we are actually generation some Buffers
    if (n > 0)
    {
        // Check the pointer is valid (and points to enough memory to store Buffer Names)
        if (!IsBadWritePtr((void*)puiBuffers, n * sizeof(ALuint)))
        {
            ALbuffer **list = &g_pBuffers;
            while(*list)
                list = &(*list)->next;

            // Create all the new Buffers
            while(i < n)
            {
                *list = calloc(1, sizeof(ALbuffer));
                if(!(*list))
                {
                    alDeleteBuffers(i, puiBuffers);
                    alSetError(AL_OUT_OF_MEMORY);
                    break;
                }

                puiBuffers[i] = (ALuint)ALTHUNK_ADDENTRY(*list);
                (*list)->state = UNUSED;
                g_uiBufferCount++;
                i++;

                list = &(*list)->next;
            }
        }
        else
        {
            // Pointer does not point to enough memory to write Buffer names
            alSetError(AL_INVALID_VALUE);
        }
    }

    ProcessContext(Context);

    return;
}

/*
*    alDeleteBuffers(ALsizei n, ALuint *puiBuffers)
*
*    Deletes the n AL Buffers pointed to by puiBuffers
*/
ALAPI ALvoid ALAPIENTRY alDeleteBuffers(ALsizei n, const ALuint *puiBuffers)
{
    ALCcontext *Context;
    ALbuffer *ALBuf;
    ALsizei i;
    ALboolean bFailed = AL_FALSE;

    Context = alcGetCurrentContext();
    SuspendContext(Context);

    // Check we are actually Deleting some Buffers
    if (n >= 0)
    {
        // Check that all the buffers are valid and can actually be deleted
        for (i = 0; i < n; i++)
        {
            // Check for valid Buffer ID (can be NULL buffer)
            if (alIsBuffer(puiBuffers[i]))
            {
                // If not the NULL buffer, check that the reference count is 0
                ALBuf = ((ALbuffer *)ALTHUNK_LOOKUPENTRY(puiBuffers[i]));
                if (ALBuf)
                {
                    if (ALBuf->refcount != 0)
                    {
                        // Buffer still in use, cannot be deleted
                        alSetError(AL_INVALID_OPERATION);
                        bFailed = AL_TRUE;
                    }
                }
            }
            else
            {
                // Invalid Buffer
                alSetError(AL_INVALID_NAME);
                bFailed = AL_TRUE;
            }
        }

        // If all the Buffers were valid (and have Reference Counts of 0), then we can delete them
        if (!bFailed)
        {
            for (i = 0; i < n; i++)
            {
                if (puiBuffers[i] && alIsBuffer(puiBuffers[i]))
                {
                    ALbuffer **list = &g_pBuffers;

                    ALBuf=((ALbuffer *)ALTHUNK_LOOKUPENTRY(puiBuffers[i]));
                    while(*list && *list != ALBuf)
                        list = &(*list)->next;

                    if(*list)
                        *list = (*list)->next;

                    // Release the memory used to store audio data
                    free(ALBuf->data);

                    // Release buffer structure
                    ALTHUNK_REMOVEENTRY(puiBuffers[i]);
                    memset(ALBuf, 0, sizeof(ALbuffer));
                    g_uiBufferCount--;
                    free(ALBuf);
                }
            }
        }
    }
    else
        alSetError(AL_INVALID_VALUE);

    ProcessContext(Context);

    return;

}

/*
*    alIsBuffer(ALuint uiBuffer)
*
*    Checks if ulBuffer is a valid Buffer Name
*/
ALAPI ALboolean ALAPIENTRY alIsBuffer(ALuint uiBuffer)
{
    ALCcontext *Context;
    ALboolean result=AL_FALSE;
    ALbuffer *ALBuf;
    ALbuffer *TgtALBuf;

    Context = alcGetCurrentContext();
    SuspendContext(Context);

    if (uiBuffer)
    {
        TgtALBuf = (ALbuffer *)ALTHUNK_LOOKUPENTRY(uiBuffer);

        // Check through list of generated buffers for uiBuffer
        ALBuf = g_pBuffers;
        while (ALBuf)
        {
            if (ALBuf == TgtALBuf)
            {
                result = AL_TRUE;
                break;
            }

            ALBuf = ALBuf->next;
        }
    }
    else
    {
        result = AL_TRUE;
    }


    ProcessContext(Context);

    return result;
}

/*
*    alBufferData(ALuint buffer,ALenum format,ALvoid *data,ALsizei size,ALsizei freq)
*
*    Fill buffer with audio data
*/
ALAPI ALvoid ALAPIENTRY alBufferData(ALuint buffer,ALenum format,const ALvoid *data,ALsizei size,ALsizei freq)
{
    ALCcontext *Context;
    ALsizei padding = 2;
    ALbuffer *ALBuf;
    ALvoid *temp;

    Context = alcGetCurrentContext();
    SuspendContext(Context);

    if (alIsBuffer(buffer) && (buffer != 0))
    {
        ALBuf=((ALbuffer *)ALTHUNK_LOOKUPENTRY(buffer));
        if ((ALBuf->refcount==0)&&(data))
        {
            switch(format)
            {
                case AL_FORMAT_MONO8:
                case AL_FORMAT_MONO16:
                case AL_FORMAT_MONO_FLOAT32:
                    LoadData(ALBuf, data, size, freq, format, AL_FORMAT_MONO16);
                    break;

                case AL_FORMAT_STEREO8:
                case AL_FORMAT_STEREO16:
                case AL_FORMAT_STEREO_FLOAT32:
                    LoadData(ALBuf, data, size, freq, format, AL_FORMAT_STEREO16);
                    break;

                case AL_FORMAT_REAR8:
                case AL_FORMAT_REAR16:
                case AL_FORMAT_REAR32: {
                    ALuint NewFormat = AL_FORMAT_QUAD16;
                    ALuint NewChannels = aluChannelsFromFormat(NewFormat);
                    ALuint OrigBytes = ((format==AL_FORMAT_REAR8) ? 1 :
                                        ((format==AL_FORMAT_REAR16) ? 2 :
                                         4));

                    assert(aluBytesFromFormat(NewFormat) == 2);

                    if((size%(OrigBytes*2)) != 0)
                    {
                        alSetError(AL_INVALID_VALUE);
                        break;
                    }

                    size /= OrigBytes;
                    size *= 2;

                    // Samples are converted to 16 bit here
                    temp = realloc(ALBuf->data, (padding*NewChannels + size) * sizeof(ALshort));
                    if(temp)
                    {
                        ALBuf->data = temp;
                        ConvertDataRear(ALBuf->data, data, OrigBytes, size);

                        memset(&(ALBuf->data[size]), 0, padding*NewChannels*sizeof(ALshort));

                        ALBuf->format = NewFormat;
                        ALBuf->eOriginalFormat = format;
                        ALBuf->size = size*sizeof(ALshort);
                        ALBuf->frequency = freq;
                        ALBuf->padding = padding;
                    }
                    else
                        alSetError(AL_OUT_OF_MEMORY);
                }   break;

                case AL_FORMAT_QUAD8_LOKI:
                case AL_FORMAT_QUAD16_LOKI:
                case AL_FORMAT_QUAD8:
                case AL_FORMAT_QUAD16:
                case AL_FORMAT_QUAD32:
                    LoadData(ALBuf, data, size, freq, format, AL_FORMAT_QUAD16);
                    break;

                case AL_FORMAT_51CHN8:
                case AL_FORMAT_51CHN16:
                case AL_FORMAT_51CHN32:
                    LoadData(ALBuf, data, size, freq, format, AL_FORMAT_51CHN16);
                    break;

                case AL_FORMAT_61CHN8:
                case AL_FORMAT_61CHN16:
                case AL_FORMAT_61CHN32:
                    LoadData(ALBuf, data, size, freq, format, AL_FORMAT_61CHN16);
                    break;

                case AL_FORMAT_71CHN8:
                case AL_FORMAT_71CHN16:
                case AL_FORMAT_71CHN32:
                    LoadData(ALBuf, data, size, freq, format, AL_FORMAT_71CHN16);
                    break;

                case AL_FORMAT_MONO_IMA4:
                case AL_FORMAT_STEREO_IMA4: {
                    int OrigChans = ((format==AL_FORMAT_MONO_IMA4) ? 1 : 2);

                    // Here is where things vary:
                    // nVidia and Apple use 64+1 samples per channel per block => block_size=36*chans bytes
                    // Most PC sound software uses 2040+1 samples per channel per block -> block_size=1024*chans bytes
                    if((size%(36*OrigChans)) != 0)
                    {
                        alSetError(AL_INVALID_VALUE);
                        break;
                    }

                    size /= 36;
                    size *= 65;

                    // Allocate extra padding samples
                    temp = realloc(ALBuf->data, (padding*OrigChans + size)*sizeof(ALshort));
                    if(temp)
                    {
                        ALBuf->data = temp;
                        ConvertDataIMA4(ALBuf->data, data, OrigChans, size/65);

                        memset(&(ALBuf->data[size]), 0, padding*sizeof(ALshort)*OrigChans);

                        ALBuf->format = ((OrigChans==1) ? AL_FORMAT_MONO16 : AL_FORMAT_STEREO16);
                        ALBuf->eOriginalFormat = format;
                        ALBuf->size = size*sizeof(ALshort);
                        ALBuf->frequency = freq;
                        ALBuf->padding = padding;
                    }
                    else
                        alSetError(AL_OUT_OF_MEMORY);
                }   break;

                default:
                    alSetError(AL_INVALID_ENUM);
                    break;
            }
        }
        else
        {
            // Buffer is in use, or data is a NULL pointer
            alSetError(AL_INVALID_VALUE);
        }
    }
    else
    {
        // Invalid Buffer Name
        alSetError(AL_INVALID_NAME);
    }

    ProcessContext(Context);
}

/*
*    alBufferSubDataEXT(ALuint buffer,ALenum format,ALvoid *data,ALsizei offset,ALsizei length)
*
*    Fill buffer with audio data
*/
ALvoid ALAPIENTRY alBufferSubDataEXT(ALuint buffer,ALenum format,const ALvoid *data,ALsizei offset,ALsizei length)
{
    ALCcontext *Context;
    ALbuffer *ALBuf;

    Context = alcGetCurrentContext();
    SuspendContext(Context);

    if(alIsBuffer(buffer) && buffer != 0)
    {
        ALBuf = (ALbuffer*)ALTHUNK_LOOKUPENTRY(buffer);
        if(ALBuf->data == NULL)
        {
            // buffer does not have any data
            alSetError(AL_INVALID_NAME);
        }
        else if(length < 0 || offset < 0 || (length > 0 && data == NULL))
        {
            // data is NULL or offset/length is negative
            alSetError(AL_INVALID_VALUE);
        }
        else
        {
            switch(format)
            {
                case AL_FORMAT_REAR8:
                case AL_FORMAT_REAR16:
                case AL_FORMAT_REAR32: {
                    ALuint OrigBytes = ((format==AL_FORMAT_REAR8) ? 1 :
                                        ((format==AL_FORMAT_REAR16) ? 2 :
                                         4));

                    if(ALBuf->eOriginalFormat != AL_FORMAT_REAR8 &&
                       ALBuf->eOriginalFormat != AL_FORMAT_REAR16 &&
                       ALBuf->eOriginalFormat != AL_FORMAT_REAR32)
                    {
                        alSetError(AL_INVALID_ENUM);
                        break;
                    }

                    if(ALBuf->size/4/sizeof(ALshort) < (ALuint)offset+length)
                    {
                        alSetError(AL_INVALID_VALUE);
                        break;
                    }

                    ConvertDataRear(&ALBuf->data[offset*4], data, OrigBytes, length*2);
                }   break;

                case AL_FORMAT_MONO_IMA4:
                case AL_FORMAT_STEREO_IMA4: {
                    int Channels = aluChannelsFromFormat(ALBuf->format);

                    if(ALBuf->eOriginalFormat != format)
                    {
                        alSetError(AL_INVALID_ENUM);
                        break;
                    }

                    if((offset%65) != 0 || (length%65) != 0 ||
                       ALBuf->size/Channels/sizeof(ALshort) < (ALuint)offset+length)
                    {
                        alSetError(AL_INVALID_VALUE);
                        break;
                    }

                    ConvertDataIMA4(&ALBuf->data[offset*Channels], data, Channels, length/65*Channels);
                }   break;

                default: {
                    ALuint Channels = aluChannelsFromFormat(format);
                    ALuint Bytes = aluBytesFromFormat(format);

                    if(Channels != aluChannelsFromFormat(ALBuf->format))
                    {
                        alSetError(AL_INVALID_ENUM);
                        break;
                    }

                    if(ALBuf->size/Channels/sizeof(ALshort) < (ALuint)offset+length)
                    {
                        alSetError(AL_INVALID_VALUE);
                        break;
                    }

                    ConvertData(&ALBuf->data[offset*Channels], data, Bytes, length*Channels);
                }   break;
            }
        }
    }
    else
    {
        // Invalid Buffer Name
        alSetError(AL_INVALID_NAME);
    }

    ProcessContext(Context);
}


ALAPI void ALAPIENTRY alBufferf(ALuint buffer, ALenum eParam, ALfloat flValue)
{
    ALCcontext    *pContext;

    (void)flValue;

    pContext = alcGetCurrentContext();
    SuspendContext(pContext);

    if (alIsBuffer(buffer) && (buffer != 0))
    {
        switch(eParam)
        {
        default:
            alSetError(AL_INVALID_ENUM);
            break;
        }
    }
    else
    {
        alSetError(AL_INVALID_NAME);
    }

    ProcessContext(pContext);
}


ALAPI void ALAPIENTRY alBuffer3f(ALuint buffer, ALenum eParam, ALfloat flValue1, ALfloat flValue2, ALfloat flValue3)
{
    ALCcontext    *pContext;

    (void)flValue1;
    (void)flValue2;
    (void)flValue3;

    pContext = alcGetCurrentContext();
    SuspendContext(pContext);

    if (alIsBuffer(buffer) && (buffer != 0))
    {
        switch(eParam)
        {
        default:
            alSetError(AL_INVALID_ENUM);
            break;
        }
    }
    else
    {
        alSetError(AL_INVALID_NAME);
    }

    ProcessContext(pContext);
}


ALAPI void ALAPIENTRY alBufferfv(ALuint buffer, ALenum eParam, const ALfloat* flValues)
{
    ALCcontext    *pContext;

    (void)flValues;

    pContext = alcGetCurrentContext();
    SuspendContext(pContext);

    if (alIsBuffer(buffer) && (buffer != 0))
    {
        switch(eParam)
        {
        default:
            alSetError(AL_INVALID_ENUM);
            break;
        }
    }
    else
    {
        alSetError(AL_INVALID_NAME);
    }

    ProcessContext(pContext);
}


ALAPI void ALAPIENTRY alBufferi(ALuint buffer, ALenum eParam, ALint lValue)
{
    ALCcontext    *pContext;

    (void)lValue;

    pContext = alcGetCurrentContext();
    SuspendContext(pContext);

    if (alIsBuffer(buffer) && (buffer != 0))
    {
        switch(eParam)
        {
        default:
            alSetError(AL_INVALID_ENUM);
            break;
        }
    }
    else
    {
        alSetError(AL_INVALID_NAME);
    }

    ProcessContext(pContext);
}


ALAPI void ALAPIENTRY alBuffer3i( ALuint buffer, ALenum eParam, ALint lValue1, ALint lValue2, ALint lValue3)
{
    ALCcontext    *pContext;

    (void)lValue1;
    (void)lValue2;
    (void)lValue3;

    pContext = alcGetCurrentContext();
    SuspendContext(pContext);

    if (alIsBuffer(buffer) && (buffer != 0))
    {
        switch(eParam)
        {
        default:
            alSetError(AL_INVALID_ENUM);
            break;
        }
    }
    else
    {
        alSetError(AL_INVALID_NAME);
    }

    ProcessContext(pContext);
}


ALAPI void ALAPIENTRY alBufferiv(ALuint buffer, ALenum eParam, const ALint* plValues)
{
    ALCcontext    *pContext;

    (void)plValues;

    pContext = alcGetCurrentContext();
    SuspendContext(pContext);

    if (alIsBuffer(buffer) && (buffer != 0))
    {
        switch(eParam)
        {
        default:
            alSetError(AL_INVALID_ENUM);
            break;
        }
    }
    else
    {
        alSetError(AL_INVALID_NAME);
    }

    ProcessContext(pContext);
}


ALAPI ALvoid ALAPIENTRY alGetBufferf(ALuint buffer, ALenum eParam, ALfloat *pflValue)
{
    ALCcontext    *pContext;

    pContext = alcGetCurrentContext();
    SuspendContext(pContext);

    if (pflValue)
    {
        if (alIsBuffer(buffer) && (buffer != 0))
        {
            switch(eParam)
            {
            default:
                alSetError(AL_INVALID_ENUM);
                break;
            }
        }
        else
        {
            alSetError(AL_INVALID_NAME);
        }
    }
    else
    {
        alSetError(AL_INVALID_VALUE);
    }

    ProcessContext(pContext);
}


ALAPI void ALAPIENTRY alGetBuffer3f(ALuint buffer, ALenum eParam, ALfloat* pflValue1, ALfloat* pflValue2, ALfloat* pflValue3)
{
    ALCcontext    *pContext;

    pContext = alcGetCurrentContext();
    SuspendContext(pContext);

    if ((pflValue1) && (pflValue2) && (pflValue3))
    {
        if (alIsBuffer(buffer) && (buffer != 0))
        {
            switch(eParam)
            {
            default:
                alSetError(AL_INVALID_ENUM);
                break;
            }
        }
        else
        {
            alSetError(AL_INVALID_NAME);
        }
    }
    else
    {
        alSetError(AL_INVALID_VALUE);
    }

    ProcessContext(pContext);
}


ALAPI void ALAPIENTRY alGetBufferfv(ALuint buffer, ALenum eParam, ALfloat* pflValues)
{
    ALCcontext    *pContext;

    pContext = alcGetCurrentContext();
    SuspendContext(pContext);

    if (pflValues)
    {
        if (alIsBuffer(buffer) && (buffer != 0))
        {
            switch(eParam)
            {
            default:
                alSetError(AL_INVALID_ENUM);
                break;
            }
        }
        else
        {
            alSetError(AL_INVALID_NAME);
        }
    }
    else
    {
        alSetError(AL_INVALID_VALUE);
    }

    ProcessContext(pContext);
}


ALAPI ALvoid ALAPIENTRY alGetBufferi(ALuint buffer, ALenum eParam, ALint *plValue)
{
    ALCcontext    *pContext;
    ALbuffer    *pBuffer;

    pContext = alcGetCurrentContext();
    SuspendContext(pContext);

    if (plValue)
    {
        if (alIsBuffer(buffer) && (buffer != 0))
        {
            pBuffer = ((ALbuffer *)ALTHUNK_LOOKUPENTRY(buffer));

            switch (eParam)
            {
            case AL_FREQUENCY:
                *plValue = pBuffer->frequency;
                break;

            case AL_BITS:
                *plValue = aluBytesFromFormat(pBuffer->format) * 8;
                break;

            case AL_CHANNELS:
                *plValue = aluChannelsFromFormat(pBuffer->format);
                break;

            case AL_SIZE:
                *plValue = pBuffer->size;
                break;

            default:
                alSetError(AL_INVALID_ENUM);
                break;
            }
        }
        else
        {
            alSetError(AL_INVALID_NAME);
        }
    }
    else
    {
        alSetError(AL_INVALID_VALUE);
    }

    ProcessContext(pContext);
}


ALAPI void ALAPIENTRY alGetBuffer3i(ALuint buffer, ALenum eParam, ALint* plValue1, ALint* plValue2, ALint* plValue3)
{
    ALCcontext    *pContext;

    pContext = alcGetCurrentContext();
    SuspendContext(pContext);

    if ((plValue1) && (plValue2) && (plValue3))
    {
        if (alIsBuffer(buffer) && (buffer != 0))
        {
            switch(eParam)
            {
            default:
                alSetError(AL_INVALID_ENUM);
                break;
            }
        }
        else
        {
            alSetError(AL_INVALID_NAME);
        }
    }
    else
    {
        alSetError(AL_INVALID_VALUE);
    }

    ProcessContext(pContext);
}


ALAPI void ALAPIENTRY alGetBufferiv(ALuint buffer, ALenum eParam, ALint* plValues)
{
    ALCcontext    *pContext;

    pContext = alcGetCurrentContext();
    SuspendContext(pContext);

    if (plValues)
    {
        if (alIsBuffer(buffer) && (buffer != 0))
        {
            switch (eParam)
            {
            case AL_FREQUENCY:
            case AL_BITS:
            case AL_CHANNELS:
            case AL_SIZE:
                alGetBufferi(buffer, eParam, plValues);
                break;

            default:
                alSetError(AL_INVALID_ENUM);
                break;
            }
        }
        else
        {
            alSetError(AL_INVALID_NAME);
        }
    }
    else
    {
        alSetError(AL_INVALID_VALUE);
    }

    ProcessContext(pContext);
}

/*
 * LoadData
 *
 * Loads the specified data into the buffer, using the specified formats.
 * Currently, the new format must be 16-bit, and must have the same channel
 * configuration as the original format. This does NOT handle compressed
 * formats (eg. IMA4).
 */
static void LoadData(ALbuffer *ALBuf, const ALubyte *data, ALsizei size, ALuint freq, ALenum OrigFormat, ALenum NewFormat)
{
    ALuint NewChannels = aluChannelsFromFormat(NewFormat);
    ALuint OrigBytes = aluBytesFromFormat(OrigFormat);
    ALuint OrigChannels = aluChannelsFromFormat(OrigFormat);
    ALsizei padding = 2;
    ALvoid *temp;

    assert(aluBytesFromFormat(NewFormat) == 2);
    assert(NewChannels == OrigChannels);

    if ((size%(OrigBytes*OrigChannels)) != 0)
    {
        alSetError(AL_INVALID_VALUE);
        return;
    }

    // Samples are converted to 16 bit here
    size /= OrigBytes;
    temp = realloc(ALBuf->data, (padding*NewChannels + size) * sizeof(ALshort));
    if(temp)
    {
        ALBuf->data = temp;
        ConvertData(ALBuf->data, data, OrigBytes, size);

        memset(&(ALBuf->data[size]), 0, padding*NewChannels*sizeof(ALshort));

        ALBuf->format = NewFormat;
        ALBuf->eOriginalFormat = OrigFormat;
        ALBuf->size = size*sizeof(ALshort);
        ALBuf->frequency = freq;
        ALBuf->padding = padding;
    }
    else
        alSetError(AL_OUT_OF_MEMORY);
}

static void ConvertData(ALshort *dst, const ALvoid *src, ALint origBytes, ALsizei len)
{
    ALsizei i;
    switch(origBytes)
    {
        case 1:
            for(i = 0;i < len;i++)
                dst[i] = ((ALshort)((ALubyte*)src)[i] - 128) << 8;
            break;

        case 2:
            memcpy(dst, src, len*sizeof(ALshort));
            break;

        case 4:
            for(i = 0;i < len;i++)
            {
                ALint smp;
                smp = (((ALfloat*)src)[i] * 32767.5f - 0.5f);
                smp = min(smp,  32767);
                smp = max(smp, -32768);
                dst[i] = (ALshort)smp;
            }
            break;

        default:
            assert(0);
    }
}

static void ConvertDataRear(ALshort *dst, const ALvoid *src, ALint origBytes, ALsizei len)
{
    ALsizei i;
    switch(origBytes)
    {
        case 1:
            for(i = 0;i < len;i+=4)
            {
                dst[i+0] = 0;
                dst[i+1] = 0;
                dst[i+2] = ((ALshort)((ALubyte*)src)[i/2+0] - 128) << 8;
                dst[i+3] = ((ALshort)((ALubyte*)src)[i/2+1] - 128) << 8;
            }
            break;

        case 2:
            for(i = 0;i < len;i+=4)
            {
                dst[i+0] = 0;
                dst[i+1] = 0;
                dst[i+2] = ((ALshort*)src)[i/2+0];
                dst[i+3] = ((ALshort*)src)[i/2+1];
            }
            break;

        case 4:
            for(i = 0;i < len;i+=4)
            {
                ALint smp;
                dst[i+0] = 0;
                dst[i+1] = 0;
                smp = (((ALfloat*)src)[i/2+0] * 32767.5f - 0.5);
                smp = min(smp,  32767);
                smp = max(smp, -32768);
                dst[i+2] = (ALshort)smp;
                smp = (((ALfloat*)src)[i/2+1] * 32767.5f - 0.5);
                smp = min(smp,  32767);
                smp = max(smp, -32768);
                dst[i+3] = (ALshort)smp;
            }
            break;

        default:
            assert(0);
    }
}

static void ConvertDataIMA4(ALshort *dst, const ALvoid *src, ALint origChans, ALsizei len)
{
    const ALuint *IMAData;
    ALint Sample[2],Index[2];
    ALuint IMACode[2];
    ALsizei i,j,k,c;

    assert(origChans <= 2);

    IMAData = src;
    for(i = 0;i < len/origChans;i++)
    {
        for(c = 0;c < origChans;c++)
        {
            Sample[c] = ((ALshort*)IMAData)[0];
            Index[c] = ((ALshort*)IMAData)[1];

            Index[c] = ((Index[c]<0) ? 0 : Index[c]);
            Index[c] = ((Index[c]>88) ? 88 : Index[c]);

            dst[i*65*origChans + c] = (ALshort)Sample[c];

            IMAData++;
        }

        for(j = 1;j < 65;j += 8)
        {
            for(c = 0;c < origChans;c++)
                IMACode[c] = *(IMAData++);

            for(k = 0;k < 8;k++)
            {
                for(c = 0;c < origChans;c++)
                {
                    Sample[c] += ((g_IMAStep_size[Index[c]]*g_IMACodeword_4[IMACode[c]&15])/8);
                    Index[c] += g_IMAIndex_adjust_4[IMACode[c]&15];

                    if(Sample[c] < -32768) Sample[c] = -32768;
                    else if(Sample[c] > 32767) Sample[c] = 32767;

                    if(Index[c]<0) Index[c] = 0;
                    else if(Index[c]>88) Index[c] = 88;

                    dst[(i*65+j+k)*origChans + c] = (ALshort)Sample[c];
                    IMACode[c] >>= 4;
                }
            }
        }
    }
}

/*
*    ReleaseALBuffers()
*
*    INTERNAL FN : Called by DLLMain on exit to destroy any buffers that still exist
*/
ALvoid ReleaseALBuffers(ALvoid)
{
    ALbuffer *ALBuffer;
    ALbuffer *ALBufferTemp;

#ifdef _DEBUG
    if(g_uiBufferCount > 0)
        AL_PRINT("exit(): deleting %d Buffer(s)\n", g_uiBufferCount);
#endif

    ALBuffer = g_pBuffers;
    while(ALBuffer)
    {
        // Release sample data
        free(ALBuffer->data);

        // Release Buffer structure
        ALBufferTemp = ALBuffer;
        ALBuffer = ALBuffer->next;
        memset(ALBufferTemp, 0, sizeof(ALbuffer));
        free(ALBufferTemp);
    }
    g_pBuffers = NULL;
    g_uiBufferCount = 0;
}
