mirror of
https://github.com/cookiengineer/audacity
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77 lines
3.0 KiB
C
77 lines
3.0 KiB
C
#define MYRECIPLN2 1.442695040888963407359924681001892137426 // 1.0/log(2)
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/* some useful conversions between a number and its power of 2 */
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#define LOG2(a) (MYRECIPLN2*log(a)) // floating point logarithm base 2
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#define POW2(m) ((unsigned long) 1 << (m)) // integer power of 2 for m<32
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/*******************************************************************
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lower level fft stuff called by routines in fftext.c and fft2d.c
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*******************************************************************/
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void fftCosInit(long M, float *Utbl);
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/* Compute Utbl, the cosine table for ffts */
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/* of size (pow(2,M)/4 +1) */
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/* INPUTS */
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/* M = log2 of fft size */
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/* OUTPUTS */
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/* *Utbl = cosine table */
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void fftBRInit(long M, short *BRLow);
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/* Compute BRLow, the bit reversed table for ffts */
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/* of size pow(2,M/2 -1) */
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/* INPUTS */
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/* M = log2 of fft size */
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/* OUTPUTS */
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/* *BRLow = bit reversed counter table */
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void ffts1(float *ioptr, long M, long Rows, float *Utbl, short *BRLow);
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/* Compute in-place complex fft on the rows of the input array */
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/* INPUTS */
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/* *ioptr = input data array */
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/* M = log2 of fft size (ex M=10 for 1024 point fft) */
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/* Rows = number of rows in ioptr array (use Rows of 1 if ioptr is a 1 dimensional array) */
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/* *Utbl = cosine table */
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/* *BRLow = bit reversed counter table */
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/* OUTPUTS */
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/* *ioptr = output data array */
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void iffts1(float *ioptr, long M, long Rows, float *Utbl, short *BRLow);
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/* Compute in-place inverse complex fft on the rows of the input array */
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/* INPUTS */
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/* *ioptr = input data array */
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/* M = log2 of fft size */
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/* Rows = number of rows in ioptr array (use Rows of 1 if ioptr is a 1 dimensional array) */
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/* *Utbl = cosine table */
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/* *BRLow = bit reversed counter table */
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/* OUTPUTS */
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/* *ioptr = output data array */
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void rffts1(float *ioptr, long M, long Rows, float *Utbl, short *BRLow);
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/* Compute in-place real fft on the rows of the input array */
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/* The result is the complex spectra of the positive frequencies */
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/* except the location for the first complex number contains the real */
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/* values for DC and Nyquest */
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/* INPUTS */
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/* *ioptr = real input data array */
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/* M = log2 of fft size */
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/* Rows = number of rows in ioptr array (use Rows of 1 if ioptr is a 1 dimensional array) */
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/* *Utbl = cosine table */
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/* *BRLow = bit reversed counter table */
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/* OUTPUTS */
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/* *ioptr = output data array in the following order */
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/* Re(x[0]), Re(x[N/2]), Re(x[1]), Im(x[1]), Re(x[2]), Im(x[2]), ... Re(x[N/2-1]), Im(x[N/2-1]). */
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void riffts1(float *ioptr, long M, long Rows, float *Utbl, short *BRLow);
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/* Compute in-place real ifft on the rows of the input array */
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/* data order as from rffts1 */
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/* INPUTS */
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/* *ioptr = input data array in the following order */
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/* M = log2 of fft size */
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/* Re(x[0]), Re(x[N/2]), Re(x[1]), Im(x[1]), Re(x[2]), Im(x[2]), ... Re(x[N/2-1]), Im(x[N/2-1]). */
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/* Rows = number of rows in ioptr array (use Rows of 1 if ioptr is a 1 dimensional array) */
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/* *Utbl = cosine table */
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/* *BRLow = bit reversed counter table */
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/* OUTPUTS */
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/* *ioptr = real output data array */
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