fft_template.c File Reference

FFT/IFFT transforms. More...

#include <stdlib.h>
#include <string.h>
#include "libavutil/mathematics.h"
#include "libavutil/thread.h"
#include "fft.h"
#include "fft-internal.h"

Classes
struct	CosTabsInitOnce

Macros
#define	INIT_FF_COS_TABS_FUNC(index, size)
#define	BUTTERFLIES(a0, a1, a2, a3)
#define	BUTTERFLIES_BIG(a0, a1, a2, a3)
#define	TRANSFORM(a0, a1, a2, a3, wre, wim)
#define	TRANSFORM_ZERO(a0, a1, a2, a3)
#define	PASS(name)
#define	BUTTERFLIES   BUTTERFLIES_BIG
#define	DECL_FFT(n, n2, n4)
#define	pass   pass_big

Typedefs
typedef struct CosTabsInitOnce	CosTabsInitOnce

Functions
	COSTABLE (16)
	COSTABLE (32)
	COSTABLE (64)
	COSTABLE (128)
	COSTABLE (256)
	COSTABLE (512)
	COSTABLE (1024)
	COSTABLE (2048)
	COSTABLE (4096)
	COSTABLE (8192)
	COSTABLE (16384)
	COSTABLE (32768)
	COSTABLE (65536)
	COSTABLE (131072)
COSTABLE_CONST FFTSample *const	FFT_NAME (ff_cos_tabs)[]
av_cold void	ff_init_ff_cos_tabs (int index)
	Initialize the cosine table in ff_cos_tabs[index]. More...
av_cold int	ff_fft_init (FFTContext *s, int nbits, int inverse)
	Set up a complex FFT. More...
av_cold void	ff_fft_end (FFTContext *s)

Detailed Description

FFT/IFFT transforms.

Macro Definition Documentation

BUTTERFLIES

#define BUTTERFLIES	(		a0,
			a1,
			a2,
			a3
	)

Value:

{\
    BF(t3, t5, t5, t1);\
    BF(a2.re, a0.re, a0.re, t5);\
    BF(a3.im, a1.im, a1.im, t3);\
    BF(t4, t6, t2, t6);\
    BF(a3.re, a1.re, a1.re, t4);\
    BF(a2.im, a0.im, a0.im, t6);\
}

BUTTERFLIES_BIG

#define BUTTERFLIES_BIG	(		a0,
			a1,
			a2,
			a3
	)

Value:

{\
    FFTSample r0=a0.re, i0=a0.im, r1=a1.re, i1=a1.im;\
    BF(t3, t5, t5, t1);\
    BF(a2.re, a0.re, r0, t5);\
    BF(a3.im, a1.im, i1, t3);\
    BF(t4, t6, t2, t6);\
    BF(a3.re, a1.re, r1, t4);\
    BF(a2.im, a0.im, i0, t6);\
}

DECL_FFT

#define DECL_FFT	(		n,
			n2,
			n4
	)

Value:

static void fft##n(FFTComplex *z)\
{\
    fft##n2(z);\
    fft##n4(z+n4*2);\
    fft##n4(z+n4*3);\
    pass(z,FFT_NAME(ff_cos_##n),n4/2);\
}

INIT_FF_COS_TABS_FUNC

#define INIT_FF_COS_TABS_FUNC	(		index,
			size
	)

Value:

static av_cold void init_ff_cos_tabs_ ## size (void)\
{                                                   \
    init_ff_cos_tabs(index);                        \
}

PASS

#define PASS

(

name

)

Value:

static void name(FFTComplex *z, const FFTSample *wre, unsigned int n)\
{\
    FFTDouble t1, t2, t3, t4, t5, t6;\
    int o1 = 2*n;\
    int o2 = 4*n;\
    int o3 = 6*n;\
    const FFTSample *wim = wre+o1;\
    n--;\
\
    TRANSFORM_ZERO(z[0],z[o1],z[o2],z[o3]);\
    TRANSFORM(z[1],z[o1+1],z[o2+1],z[o3+1],wre[1],wim[-1]);\
    do {\
        z += 2;\
        wre += 2;\
        wim -= 2;\
        TRANSFORM(z[0],z[o1],z[o2],z[o3],wre[0],wim[0]);\
        TRANSFORM(z[1],z[o1+1],z[o2+1],z[o3+1],wre[1],wim[-1]);\
    } while(--n);\
}

TRANSFORM

#define TRANSFORM	(		a0,
			a1,
			a2,
			a3,
			wre,
			wim
	)

Value:

{\
    CMUL(t1, t2, a2.re, a2.im, wre, -wim);\
    CMUL(t5, t6, a3.re, a3.im, wre,  wim);\
    BUTTERFLIES(a0,a1,a2,a3)\
}

TRANSFORM_ZERO

#define TRANSFORM_ZERO	(		a0,
			a1,
			a2,
			a3
	)

Value:

{\
    t1 = a2.re;\
    t2 = a2.im;\
    t5 = a3.re;\
    t6 = a3.im;\
    BUTTERFLIES(a0,a1,a2,a3)\
}

Function Documentation

ff_fft_init()

av_cold int ff_fft_init	(	FFTContext *	s,
		int	nbits,
		int	inverse
	)

Set up a complex FFT.

Parameters

nbits	log2 of the length of the input array
inverse	if 0 perform the forward transform, if 1 perform the inverse

ff_init_ff_cos_tabs()

av_cold void ff_init_ff_cos_tabs

(

int

index

)

Initialize the cosine table in ff_cos_tabs[index].

Parameters

index

index in ff_cos_tabs array of the table to initialize