lib/psys/pa_lib.c

/*
 * Portable Audio I/O Library
 * Host Independant Layer
 *
 * Based on the Open Source API proposed by Ross Bencina
 * Copyright (c) 1999-2000 Phil Burk
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files
 * (the "Software"), to deal in the Software without restriction,
 * including without limitation the rights to use, copy, modify, merge,
 * publish, distribute, sublicense, and/or sell copies of the Software,
 * and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * Any person wishing to distribute modifications to the Software is
 * requested to send the modifications to the original developer so that
 * they can be incorporated into the canonical version.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
 * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
 * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 */

/* Modification History:
 PLB20010422 - apply Mike Berry's changes for CodeWarrior on PC
 PLB20010820 - fix dither and shift for recording PaUInt8 format
*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

/* PLB20010422 - "memory.h" doesn't work on CodeWarrior for PC. Thanks Mike Berry for the mod. */
#ifdef _WIN32
#ifndef __MWERKS__
#include <memory.h>
#endif  /* __MWERKS__ */
#else   /* !_WIN32 */
#include <memory.h>
#endif  /* _WIN32 */

#if 0
#include "portaudio.h"
#include "pa_host.h"
#include "pa_trace.h"
#endif

/* The reason we might NOT want to validate the rate before opening the stream
 * is because many DirectSound drivers lie about the rates they actually support.
 */
#define PA_VALIDATE_RATE    (0)   /* If true validate sample rate against driver info. */

/*
O- maybe not allocate past_InputBuffer and past_OutputBuffer if not needed for conversion
*/

#ifndef FALSE
	#define FALSE  (0)
	#define TRUE   (!FALSE)
#endif

#define PRINT(x) { printf x; fflush(stdout); }
#define ERR_RPT(x) PRINT(x)
#define DBUG(x)  /* PRINT(x) */
#define DBUGX(x) /* PRINT(x) */

static int gInitCount = 0; /* Count number of times Pa_Initialize() called to allow nesting and overlapping. */

static PaError Pa_KillStream(  PortAudioStream *stream, int abort );

/***********************************************************************/
int PaHost_FindClosestTableEntry( double allowableError,  const double *rateTable, int numRates, double frameRate )
{
	double err, minErr = allowableError;
	int i, bestFit = -1;

	for( i=0; i<numRates; i++ )
	{
		err = fabs( frameRate - rateTable[i] );
		if( err < minErr )
		{
			minErr = err;
			bestFit = i;
		}
	}
	return bestFit;
}

/**************************************************************************
** Make sure sample rate is legal and also convert to enumeration for driver.
*/
PaError PaHost_ValidateSampleRate( PaDeviceID id, double requestedFrameRate,
	double *closestFrameRatePtr )
{
	long bestRateIndex;
	const PaDeviceInfo *pdi;
	pdi = Pa_GetDeviceInfo( id );
	if( pdi == NULL )
	{
		return paInvalidDeviceId;
	}

	if( pdi->numSampleRates == -1 )
	{
	/* Is it out of range? */
		if( (requestedFrameRate < pdi->sampleRates[0]) ||
			(requestedFrameRate > pdi->sampleRates[1]) )
		{
			return paInvalidSampleRate;
		}

		*closestFrameRatePtr = requestedFrameRate;
	}
	else
	{
		bestRateIndex = PaHost_FindClosestTableEntry( 1.0, pdi->sampleRates, pdi->numSampleRates, requestedFrameRate );
		if( bestRateIndex < 0 ) return paInvalidSampleRate;
		*closestFrameRatePtr = pdi->sampleRates[bestRateIndex];
	}
	return paNoError;
}

/*************************************************************************/
PaError Pa_OpenStream(
		PortAudioStream** streamPtrPtr,
		PaDeviceID inputDeviceID,
		int numInputChannels,
		PaSampleFormat inputSampleFormat,
		void *inputDriverInfo,
		PaDeviceID outputDeviceID,
		int numOutputChannels,
		PaSampleFormat outputSampleFormat,
		void *outputDriverInfo,
		double sampleRate,
		unsigned long framesPerBuffer,
		unsigned long numberOfBuffers,
		unsigned long streamFlags,
		PortAudioCallback *callback,
		void *userData )
{
	internalPortAudioStream   *past = NULL;
	PaError                    result = paNoError;
	int                        bitsPerInputSample;
	int                        bitsPerOutputSample;
/* Print passed parameters. */
	DBUG(("Pa_OpenStream( %p, %d, %d, %d, %p, /* input */ \n",
			streamPtrPtr, inputDeviceID, numInputChannels,
			inputSampleFormat, inputDriverInfo ));
	DBUG(("               %d, %d, %d, %p, /* output */\n",
			outputDeviceID, numOutputChannels,
			outputSampleFormat, outputDriverInfo ));
	DBUG(("               %g, %d, %d, 0x%x, , %p )\n",
			sampleRate, framesPerBuffer, numberOfBuffers,
			streamFlags, userData ));

/* Check for parameter errors. */
	if( (streamFlags & ~(paClipOff | paDitherOff)) != 0 ) return paInvalidFlag;
	if( streamPtrPtr == NULL ) return paBadStreamPtr;
	if( inputDriverInfo != NULL ) return paHostError; /* REVIEW */
	if( outputDriverInfo != NULL ) return paHostError; /* REVIEW */
	if( (inputDeviceID < 0) && ( outputDeviceID < 0) ) return paInvalidDeviceId;
	if( (outputDeviceID >= Pa_CountDevices()) || (inputDeviceID >= Pa_CountDevices()) )
	{
		return paInvalidDeviceId;
	}
	if( (numInputChannels <= 0) && ( numOutputChannels <= 0) ) return paInvalidChannelCount;

#if SUPPORT_AUDIO_CAPTURE
	if( inputDeviceID >= 0 )
	{
		PaError size = Pa_GetSampleSize( inputSampleFormat );
		if( size < 0 ) return size;
		bitsPerInputSample = 8 * size;
		if( (numInputChannels <= 0) ) return paInvalidChannelCount;
	}
#else
	if( inputDeviceID >= 0 )
	{
		return paInvalidChannelCount;
	}
#endif /* SUPPORT_AUDIO_CAPTURE */
	else
	{
		if( numInputChannels > 0 ) return paInvalidChannelCount;
		bitsPerInputSample = 0;
	}

	if( outputDeviceID >= 0 )
	{
		PaError size = Pa_GetSampleSize( outputSampleFormat );
		if( size < 0 ) return size;
		bitsPerOutputSample = 8 * size;
		if( (numOutputChannels <= 0) ) return paInvalidChannelCount;
	}
	else
	{
		if( numOutputChannels > 0 ) return paInvalidChannelCount;
		bitsPerOutputSample = 0;
	}

	if( callback == NULL ) return paNullCallback;

/* Allocate and clear stream structure. */
	past = (internalPortAudioStream *) PaHost_AllocateFastMemory( sizeof(internalPortAudioStream) );
	if( past == NULL ) return paInsufficientMemory;
	memset( past, 0, sizeof(internalPortAudioStream) );
	AddTraceMessage("Pa_OpenStream: past", (long) past );

	past->past_Magic = PA_MAGIC;  /* Set ID to catch bugs. */
	past->past_FramesPerUserBuffer = framesPerBuffer;
	past->past_NumUserBuffers = numberOfBuffers; /* NOTE - PaHost_OpenStream() NMUST CHECK FOR ZERO! */
	past->past_Callback = callback;
	past->past_UserData = userData;
	past->past_OutputSampleFormat = outputSampleFormat;
	past->past_InputSampleFormat = inputSampleFormat;
	past->past_OutputDeviceID = outputDeviceID;
	past->past_InputDeviceID = inputDeviceID;
	past->past_NumInputChannels = numInputChannels;
	past->past_NumOutputChannels = numOutputChannels;
	past->past_Flags = streamFlags;

/* Check for absurd sample rates. */
	if( (sampleRate < 1000.0) || (sampleRate > 200000.0) )
	{
		result = paInvalidSampleRate;
		goto cleanup;
	}

/* Allocate buffers that may be used for format conversion from user to native buffers. */
	if( numInputChannels > 0 )
	{

#if PA_VALIDATE_RATE
		result = PaHost_ValidateSampleRate( inputDeviceID, sampleRate, &past->past_SampleRate );
		if( result < 0 )
		{
			goto cleanup;
		}
#else
		past->past_SampleRate = sampleRate;
#endif
/* Allocate single Input buffer. */
		past->past_InputBufferSize = framesPerBuffer * numInputChannels * ((bitsPerInputSample+7) / 8);
		past->past_InputBuffer = PaHost_AllocateFastMemory(past->past_InputBufferSize);
		if( past->past_InputBuffer == NULL )
		{
			result = paInsufficientMemory;
			goto cleanup;
		}
	}
	else
	{
		past->past_InputBuffer = NULL;
	}

/* Allocate single Output buffer. */
	if( numOutputChannels > 0 )
	{
#if PA_VALIDATE_RATE
		result = PaHost_ValidateSampleRate( outputDeviceID, sampleRate, &past->past_SampleRate );
		if( result < 0 )
		{
			goto cleanup;
		}
#else
		past->past_SampleRate = sampleRate;
#endif
		past->past_OutputBufferSize = framesPerBuffer * numOutputChannels * ((bitsPerOutputSample+7) / 8);
		past->past_OutputBuffer = PaHost_AllocateFastMemory(past->past_OutputBufferSize);
		if( past->past_OutputBuffer == NULL )
		{
			result = paInsufficientMemory;
			goto cleanup;
		}
	}
	else
	{
		past->past_OutputBuffer = NULL;
	}

	result = PaHost_OpenStream( past );
	if( result < 0 ) goto cleanup;

	*streamPtrPtr = (void *) past;

	return result;

cleanup:
	if( past != NULL ) Pa_CloseStream( past );
	*streamPtrPtr = NULL;
	return result;
}


/*************************************************************************/
PaError Pa_OpenDefaultStream( PortAudioStream** stream,
		int numInputChannels,
		int numOutputChannels,
		PaSampleFormat sampleFormat,
		double sampleRate,
		unsigned long framesPerBuffer,
		unsigned long numberOfBuffers,
		PortAudioCallback *callback,
		void *userData )
{
	return Pa_OpenStream(
		stream,
		((numInputChannels > 0) ? Pa_GetDefaultInputDeviceID() : paNoDevice),
		numInputChannels, sampleFormat, NULL,
		((numOutputChannels > 0) ? Pa_GetDefaultOutputDeviceID() : paNoDevice),
		numOutputChannels, sampleFormat, NULL,
		sampleRate, framesPerBuffer, numberOfBuffers, paNoFlag, callback, userData );
}

/*************************************************************************/
PaError Pa_CloseStream( PortAudioStream* stream)
{
	PaError   result;
	internalPortAudioStream   *past;

	DBUG(("Pa_CloseStream()\n"));
	if( stream == NULL ) return paBadStreamPtr;
	past = (internalPortAudioStream *) stream;

	Pa_AbortStream( past );
	result = PaHost_CloseStream( past );

	if( past->past_InputBuffer ) PaHost_FreeFastMemory( past->past_InputBuffer, past->past_InputBufferSize );
	if( past->past_OutputBuffer ) PaHost_FreeFastMemory( past->past_OutputBuffer, past->past_OutputBufferSize );
	PaHost_FreeFastMemory( past, sizeof(internalPortAudioStream) );

	return result;
}

/*************************************************************************/
PaError Pa_StartStream( PortAudioStream *stream )
{
	PaError result = paHostError;
	internalPortAudioStream   *past;

	if( stream == NULL ) return paBadStreamPtr;
	past = (internalPortAudioStream *) stream;

	past->past_FrameCount = 0.0;

	if( past->past_NumInputChannels > 0 )
	{
		result = PaHost_StartInput( past );
		DBUG(("Pa_StartStream: PaHost_StartInput returned = 0x%X.\n", result));
		if( result < 0 ) goto error;
	}

	if( past->past_NumOutputChannels > 0 )
	{
		result = PaHost_StartOutput( past );
		DBUG(("Pa_StartStream: PaHost_StartOutput returned = 0x%X.\n", result));
		if( result < 0 ) goto error;
	}

	result = PaHost_StartEngine( past );
	DBUG(("Pa_StartStream: PaHost_StartEngine returned = 0x%X.\n", result));
	if( result < 0 ) goto error;

	return paNoError;

error:
	return result;
}

/*************************************************************************/
PaError Pa_StopStream(  PortAudioStream *stream )
{
	return Pa_KillStream( stream, 0 );
}

/*************************************************************************/
PaError Pa_AbortStream(  PortAudioStream *stream )
{
	return Pa_KillStream( stream, 1 );
}

/*************************************************************************/
static PaError Pa_KillStream(  PortAudioStream *stream, int abort )
{
	PaError result = paNoError;
	internalPortAudioStream   *past;

	DBUG(("Pa_StopStream().\n"));
	if( stream == NULL ) return paBadStreamPtr;
	past = (internalPortAudioStream *) stream;

	if( (past->past_NumInputChannels > 0) || (past->past_NumOutputChannels > 0) )
	{
		result = PaHost_StopEngine( past, abort );
		DBUG(("Pa_StopStream: PaHost_StopEngine returned = 0x%X.\n", result));
		if( result < 0 ) goto error;
	}

	if( past->past_NumInputChannels > 0 )
	{
		result = PaHost_StopInput( past, abort );
		DBUG(("Pa_StopStream: PaHost_StopInput returned = 0x%X.\n", result));
		if( result != paNoError ) goto error;
	}

	if( past->past_NumOutputChannels > 0 )
	{
		result = PaHost_StopOutput( past, abort );
		DBUG(("Pa_StopStream: PaHost_StopOutput returned = 0x%X.\n", result));
		if( result != paNoError ) goto error;
	}

error:
	past->past_Usage = 0;
	past->past_IfLastExitValid = 0;

	return result;
}

/*************************************************************************/
PaError Pa_StreamActive( PortAudioStream *stream )
{
	internalPortAudioStream   *past;
	if( stream == NULL ) return paBadStreamPtr;
	past = (internalPortAudioStream *) stream;
	return PaHost_StreamActive( past );
}

/*************************************************************************/
const char *Pa_GetErrorText( PaError errnum )
{
	const char *msg;

	switch(errnum)
	{
	case paNoError:                  msg = "Success"; break;
	case paHostError:                msg = "Host error."; break;
	case paInvalidChannelCount:      msg = "Invalid number of channels."; break;
	case paInvalidSampleRate:        msg = "Invalid sample rate."; break;
	case paInvalidDeviceId:          msg = "Invalid device ID."; break;
	case paInvalidFlag:              msg = "Invalid flag."; break;
	case paSampleFormatNotSupported: msg = "Sample format not supported"; break;
	case paBadIODeviceCombination:   msg = "Illegal combination of I/O devices."; break;
	case paInsufficientMemory:       msg = "Insufficient memory."; break;
	case paBufferTooBig:             msg = "Buffer too big."; break;
	case paBufferTooSmall:           msg = "Buffer too small."; break;
	case paNullCallback:             msg = "No callback routine specified."; break;
	case paBadStreamPtr:             msg = "Invalid stream pointer."; break;
	case paTimedOut    :             msg = "Wait Timed Out."; break;
	case paInternalError:            msg = "Internal PortAudio Error."; break;
	default:                         msg = "Illegal error number."; break;
	}
	return msg;
}

/*
	Get CPU Load as a fraction of total CPU time.
	A value of 0.5 would imply that PortAudio and the sound generating
	callback was consuming roughly 50% of the available CPU time.
	The amount may vary depending on CPU load.
	This function may be called from the callback function.
*/
double Pa_GetCPULoad(  PortAudioStream* stream)
{
	internalPortAudioStream   *past;
	if( stream == NULL ) return (double) paBadStreamPtr;
	past = (internalPortAudioStream *) stream;
	return past->past_Usage;
}

/*************************************************************
** Calculate 2 LSB dither signal with a triangular distribution.
** Ranged properly for adding to a 32 bit integer prior to >>15.
*/
#define DITHER_BITS   (15)
#define DITHER_SCALE  (1.0f / ((1<<DITHER_BITS)-1))
static long Pa_TriangularDither( void )
{
	static unsigned long previous = 0;
	static unsigned long randSeed1 = 22222;
	static unsigned long randSeed2 = 5555555;
	long current, highPass;
/* Generate two random numbers. */
	randSeed1 = (randSeed1 * 196314165) + 907633515;
	randSeed2 = (randSeed2 * 196314165) + 907633515;
/* Generate triangular distribution about 0. */
	current = (((long)randSeed1)>>(32-DITHER_BITS)) + (((long)randSeed2)>>(32-DITHER_BITS));
 /* High pass filter to reduce audibility. */
	highPass = current - previous;
	previous = current;
	return highPass;
}

/*************************************************************************
** Called by host code.
** Convert input from Int16, call user code, then convert output
** to Int16 format for native use.
** Assumes host native format is paInt16.
** Returns result from user callback.
*/
long Pa_CallConvertInt16( internalPortAudioStream   *past,
	short *nativeInputBuffer,
	short *nativeOutputBuffer )
{
	long              temp;
	long              bytesEmpty = 0;
	long              bytesFilled = 0;
	int               userResult;
	unsigned int      i;
	void             *inputBuffer = NULL;
	void             *outputBuffer = NULL;

#if SUPPORT_AUDIO_CAPTURE
/* Get native data from DirectSound. */
	if( (past->past_NumInputChannels > 0) && (nativeInputBuffer != NULL) )
	{
/* Convert from native format to PA format. */
		unsigned int samplesPerBuffer = past->past_FramesPerUserBuffer * past->past_NumInputChannels;
		switch(past->past_InputSampleFormat)
		{

		case paFloat32:
			{
				float *inBufPtr = (float *) past->past_InputBuffer;
				inputBuffer = past->past_InputBuffer;
				for( i=0; i<samplesPerBuffer; i++ )
				{
					inBufPtr[i] = nativeInputBuffer[i] * (1.0f / 32767.0f);
				}
				break;
			}

		case paInt32:
			{
			/* Convert 16 bit data to 32 bit integers */
				int *inBufPtr = (int *) past->past_InputBuffer;
				inputBuffer = past->past_InputBuffer;
				for( i=0; i<samplesPerBuffer; i++ )
				{
					inBufPtr[i] = nativeInputBuffer[i] << 16;
				}
				break;
			}

		case paInt16:
			{
			/* Already in correct format so don't copy. */
				inputBuffer = nativeInputBuffer;
				break;
			}

		case paInt8:
			{
			/* Convert 16 bit data to 8 bit chars */
				char *inBufPtr = (char *) past->past_InputBuffer;
				inputBuffer = past->past_InputBuffer;
				if( past->past_Flags & paDitherOff )
				{
					for( i=0; i<samplesPerBuffer; i++ )
					{
						inBufPtr[i] = (char)(nativeInputBuffer[i] >> 8);
					}
				}
				else
				{
					for( i=0; i<samplesPerBuffer; i++ )
					{
						temp = nativeInputBuffer[i];
						temp += Pa_TriangularDither() >> 8; /* PLB20010820 */
						temp = ((temp < -0x8000) ? -0x8000 : ((temp > 0x7FFF) ? 0x7FFF : temp));
						inBufPtr[i] = (char)(temp >> 8);
					}
				}
				break;
			}

		case paUInt8:
			{
			/* Convert 16 bit data to 8 bit unsigned chars */
				unsigned char *inBufPtr = (unsigned char *) past->past_InputBuffer;
				inputBuffer = past->past_InputBuffer;
				if( past->past_Flags & paDitherOff )
				{
					for( i=0; i<samplesPerBuffer; i++ )
					{
						inBufPtr[i] = ((unsigned char)(nativeInputBuffer[i] >> 8)) + 0x80;
					}
				}
				else
				{
			/* If you dither then you have to clip because dithering could push the signal out of range! */
					for( i=0; i<samplesPerBuffer; i++ )
					{
						temp = nativeInputBuffer[i];
						temp += Pa_TriangularDither() >> 8; /* PLB20010820 */
						temp = ((temp < -0x8000) ? -0x8000 : ((temp > 0x7FFF) ? 0x7FFF : temp));
						inBufPtr[i] = (unsigned char)((temp>>8) + 0x80); /* PLB20010820 */
					}
				}
				break;
			}

		default:
			break;
		}
	}
#endif /* SUPPORT_AUDIO_CAPTURE */

/* Are we doing output time? */
	if( (past->past_NumOutputChannels > 0) && (nativeOutputBuffer != NULL) )
	{
	/* May already be in native format so just write directly to native buffer. */
		outputBuffer = (past->past_OutputSampleFormat == paInt16) ?
			nativeOutputBuffer : past->past_OutputBuffer;
	}
/*
	AddTraceMessage("Pa_CallConvertInt16: inputBuffer = ", (int) inputBuffer );
	AddTraceMessage("Pa_CallConvertInt16: outputBuffer = ", (int) outputBuffer );
*/
/* Call user callback routine. */
	userResult = past->past_Callback(
			inputBuffer,
			outputBuffer,
			past->past_FramesPerUserBuffer,
			past->past_FrameCount,
			past->past_UserData );

	past->past_FrameCount += (PaTimestamp) past->past_FramesPerUserBuffer;

/* Convert to native format if necessary. */
	if( outputBuffer != NULL )
	{
		unsigned int samplesPerBuffer = past->past_FramesPerUserBuffer * past->past_NumOutputChannels;
		switch(past->past_OutputSampleFormat)
		{
		case paFloat32:
			{
				float *outBufPtr = (float *) past->past_OutputBuffer;
				if( past->past_Flags & paDitherOff )
				{
					if( past->past_Flags & paClipOff ) /* NOTHING */
					{
						for( i=0; i<samplesPerBuffer; i++ )
						{
							*nativeOutputBuffer++ = (short) (outBufPtr[i] * (32767.0f));
						}
					}
					else /* CLIP */
					{
						for( i=0; i<samplesPerBuffer; i++ )
						{
							temp = (long)(outBufPtr[i] * 32767.0f);
							*nativeOutputBuffer++ = (short)((temp < -0x8000) ? -0x8000 : ((temp > 0x7FFF) ? 0x7FFF : temp));
						}
					}
				}
				else
				{
			/* If you dither then you have to clip because dithering could push the signal out of range! */
					for( i=0; i<samplesPerBuffer; i++ )
					{
						float dither  = Pa_TriangularDither()*DITHER_SCALE;
						float dithered = (outBufPtr[i] * (32767.0f)) + dither;
						temp = (long) (dithered);
						*nativeOutputBuffer++ = (short)((temp < -0x8000) ? -0x8000 : ((temp > 0x7FFF) ? 0x7FFF : temp));
					}
				}
				break;
			}

		case paInt32:
			{
				int *outBufPtr = (int *) past->past_OutputBuffer;
				if( past->past_Flags & paDitherOff )
				{
					for( i=0; i<samplesPerBuffer; i++ )
					{
						*nativeOutputBuffer++ = (short) (outBufPtr[i] >> 16 );
					}
				}
				else
				{
					for( i=0; i<samplesPerBuffer; i++ )
					{
				/* Shift one bit down before dithering so that we have room for overflow from add. */
						temp = (outBufPtr[i] >> 1) + Pa_TriangularDither();
						temp = temp >> 15;
						*nativeOutputBuffer++ = (short)((temp < -0x8000) ? -0x8000 : ((temp > 0x7FFF) ? 0x7FFF : temp));
					}
				}
				break;
			}

		case paInt8:
			{
				char *outBufPtr = (char *) past->past_OutputBuffer;
				for( i=0; i<samplesPerBuffer; i++ )
				{
					*nativeOutputBuffer++ = ((short)outBufPtr[i]) << 8;
				}
				break;
			}

		case paUInt8:
			{
				unsigned char *outBufPtr = (unsigned char *) past->past_OutputBuffer;
				for( i=0; i<samplesPerBuffer; i++ )
				{
					*nativeOutputBuffer++ = ((short)(outBufPtr[i] - 0x80)) << 8;
				}
				break;
			}

		default:
			break;
		}

	}

	return userResult;
}

/*************************************************************************
** Called by host code.
** Convert input from Float32, call user code, then convert output
** to Float32 format for native use.
** Assumes host native format is Float32.
** Returns result from user callback.
** FIXME - Unimplemented for formats other than paFloat32!!!!
*/
long Pa_CallConvertFloat32( internalPortAudioStream   *past,
	float *nativeInputBuffer,
	float *nativeOutputBuffer )
{
	long              bytesEmpty = 0;
	long              bytesFilled = 0;
	int               userResult;
	void             *inputBuffer = NULL;
	void             *outputBuffer = NULL;

/* Get native data from DirectSound. */
	if( (past->past_NumInputChannels > 0) && (nativeInputBuffer != NULL) )
	{
		inputBuffer = nativeInputBuffer;  /* FIXME */
	}

/* Are we doing output time? */
	if( (past->past_NumOutputChannels > 0) && (nativeOutputBuffer != NULL) )
	{
	/* May already be in native format so just write directly to native buffer. */
		outputBuffer = (past->past_OutputSampleFormat == paFloat32) ?
			nativeOutputBuffer : past->past_OutputBuffer;
	}
/*
	AddTraceMessage("Pa_CallConvertInt16: inputBuffer = ", (int) inputBuffer );
	AddTraceMessage("Pa_CallConvertInt16: outputBuffer = ", (int) outputBuffer );
*/
/* Call user callback routine. */
	userResult = past->past_Callback(
			inputBuffer,
			outputBuffer,
			past->past_FramesPerUserBuffer,
			past->past_FrameCount,
			past->past_UserData );

	past->past_FrameCount += (PaTimestamp) past->past_FramesPerUserBuffer;

/* Convert to native format if necessary. */  /* FIXME */
	return userResult;
}

/*************************************************************************/
PaError Pa_Initialize( void )
{
	if( gInitCount++ > 0 ) return paNoError;
	ResetTraceMessages();
	return PaHost_Init();
}

PaError Pa_Terminate( void )
{
	PaError result = paNoError;

	if( gInitCount == 0 ) return paNoError;
	else if( --gInitCount == 0 )
	{
		result = PaHost_Term();
		DumpTraceMessages();
	}
	return result;
}

/*************************************************************************/
PaError Pa_GetSampleSize( PaSampleFormat format )
{
	int size;
	switch(format )
	{

	case paUInt8:
	case paInt8:
		size = 1;
		break;

	case paInt16:
		size = 2;
		break;

	case paPackedInt24:
		size = 3;
		break;

	case paFloat32:
	case paInt32:
	case paInt24:
		size = 4;
		break;

	default:
		size = paSampleFormatNotSupported;
		break;
	}
	return (PaError) size;
}