diff options
Diffstat (limited to 'pd/portaudio/src/common/pa_dither.c')
| -rw-r--r-- | pd/portaudio/src/common/pa_dither.c | 29 |
1 files changed, 17 insertions, 12 deletions
diff --git a/pd/portaudio/src/common/pa_dither.c b/pd/portaudio/src/common/pa_dither.c index 6f6c9a1a..7a1b1312 100644 --- a/pd/portaudio/src/common/pa_dither.c +++ b/pd/portaudio/src/common/pa_dither.c @@ -1,5 +1,5 @@ /* - * $Id: pa_dither.c 1097 2006-08-26 08:27:53Z rossb $ + * $Id: pa_dither.c 1418 2009-10-12 21:00:53Z philburk $ * Portable Audio I/O Library triangular dither generator * * Based on the Open Source API proposed by Ross Bencina @@ -42,9 +42,14 @@ @brief Functions for generating dither noise */ - -#include "pa_dither.h" #include "pa_types.h" +#include "pa_dither.h" + + +/* 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. + */ #define PA_DITHER_BITS_ (15) @@ -57,9 +62,9 @@ void PaUtil_InitializeTriangularDitherState( PaUtilTriangularDitherGenerator *st } -signed long PaUtil_Generate16BitTriangularDither( PaUtilTriangularDitherGenerator *state ) +PaInt32 PaUtil_Generate16BitTriangularDither( PaUtilTriangularDitherGenerator *state ) { - signed long current, highPass; + PaInt32 current, highPass; /* Generate two random numbers. */ state->randSeed1 = (state->randSeed1 * 196314165) + 907633515; @@ -69,9 +74,10 @@ signed long PaUtil_Generate16BitTriangularDither( PaUtilTriangularDitherGenerato * Shift before adding to prevent overflow which would skew the distribution. * Also shift an extra bit for the high pass filter. */ -#define DITHER_SHIFT_ ((SIZEOF_LONG*8 - PA_DITHER_BITS_) + 1) - current = (((signed long)state->randSeed1)>>DITHER_SHIFT_) + - (((signed long)state->randSeed2)>>DITHER_SHIFT_); +#define DITHER_SHIFT_ ((sizeof(PaInt32)*8 - PA_DITHER_BITS_) + 1) + + current = (((PaInt32)state->randSeed1)>>DITHER_SHIFT_) + + (((PaInt32)state->randSeed2)>>DITHER_SHIFT_); /* High pass filter to reduce audibility. */ highPass = current - state->previous; @@ -86,7 +92,7 @@ static const float const_float_dither_scale_ = PA_FLOAT_DITHER_SCALE_; float PaUtil_GenerateFloatTriangularDither( PaUtilTriangularDitherGenerator *state ) { - signed long current, highPass; + PaInt32 current, highPass; /* Generate two random numbers. */ state->randSeed1 = (state->randSeed1 * 196314165) + 907633515; @@ -96,9 +102,8 @@ float PaUtil_GenerateFloatTriangularDither( PaUtilTriangularDitherGenerator *sta * Shift before adding to prevent overflow which would skew the distribution. * Also shift an extra bit for the high pass filter. */ -#define DITHER_SHIFT_ ((SIZEOF_LONG*8 - PA_DITHER_BITS_) + 1) - current = (((signed long)state->randSeed1)>>DITHER_SHIFT_) + - (((signed long)state->randSeed2)>>DITHER_SHIFT_); + current = (((PaInt32)state->randSeed1)>>DITHER_SHIFT_) + + (((PaInt32)state->randSeed2)>>DITHER_SHIFT_); /* High pass filter to reduce audibility. */ highPass = current - state->previous; |