SV platform dependency builds

#ifndef PA_DITHER_H

#define PA_DITHER_H

/*

 * $Id$

 * Portable Audio I/O Library triangular dither generator

 *

 * Based on the Open Source API proposed by Ross Bencina

 * Copyright (c) 1999-2002 Phil Burk, Ross Bencina

 *

 * 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.

 *

 * 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.

 */

/*

 * The text above constitutes the entire PortAudio license; however, 

 * the PortAudio community also makes the following non-binding requests:

 *

 * 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. It is also 

 * requested that these non-binding requests be included along with the 

 * license above.

 */

/** @file

 @ingroup common_src

 @brief Functions for generating dither noise

*/

#include "pa_types.h"

#ifdef __cplusplus

extern "C"

{

#endif /* __cplusplus */

/* Note that the linear congruential algorithm requires 32 bit integers

 * because it uses arithmetic overflow. So use PaUint32 instead of

 * unsigned long so it will work on 64 bit systems.

 */

/** @brief State needed to generate a dither signal */

typedef struct PaUtilTriangularDitherGenerator{

    PaUint32 previous;

    PaUint32 randSeed1;

    PaUint32 randSeed2;

} PaUtilTriangularDitherGenerator;

/** @brief Initialize dither state */

void PaUtil_InitializeTriangularDitherState( PaUtilTriangularDitherGenerator *ditherState );

/**

 @brief Calculate 2 LSB dither signal with a triangular distribution.

 Ranged for adding to a 1 bit right-shifted 32 bit integer

 prior to >>15. eg:

<pre>

    signed long in = *

    signed long dither = PaUtil_Generate16BitTriangularDither( ditherState );

    signed short out = (signed short)(((in>>1) + dither) >> 15);

</pre>

 @return

 A signed 32-bit integer with a range of +32767 to -32768

*/

PaInt32 PaUtil_Generate16BitTriangularDither( PaUtilTriangularDitherGenerator *ditherState );

/**

 @brief Calculate 2 LSB dither signal with a triangular distribution.

 Ranged for adding to a pre-scaled float.

<pre>

    float in = *

    float dither = PaUtil_GenerateFloatTriangularDither( ditherState );

    // use smaller scaler to prevent overflow when we add the dither

    signed short out = (signed short)(in*(32766.0f) + dither );

</pre>

 @return

 A float with a range of -2.0 to +1.99999.

*/

float PaUtil_GenerateFloatTriangularDither( PaUtilTriangularDitherGenerator *ditherState );

#ifdef __cplusplus

}

#endif /* __cplusplus */

#endif /* PA_DITHER_H */