fftsg.c | Explore in Territory

/*
Fast Fourier/Cosine/Sine Transform
    dimension   :one
    data length :power of 2
    decimation  :frequency
    radix       :split-radix
    data        :inplace
    table       :use
functions
    cdft: Complex Discrete Fourier Transform
    rdft: Real Discrete Fourier Transform
    ddct: Discrete Cosine Transform
    ddst: Discrete Sine Transform
    dfct: Cosine Transform of RDFT (Real Symmetric DFT)
    dfst: Sine Transform of RDFT (Real Anti-symmetric DFT)
function prototypes
    void cdft(int, int, double *, int *, double *);
    void rdft(int, int, double *, int *, double *);
    void ddct(int, int, double *, int *, double *);
    void ddst(int, int, double *, int *, double *);
    void dfct(int, double *, double *, int *, double *);
    void dfst(int, double *, double *, int *, double *);
macro definitions
    USE_CDFT_PTHREADS : default=not defined
        CDFT_THREADS_BEGIN_N  : must be >= 512, default=8192
        CDFT_4THREADS_BEGIN_N : must be >= 512, default=65536
    USE_CDFT_WINTHREADS : default=not defined
        CDFT_THREADS_BEGIN_N  : must be >= 512, default=32768
        CDFT_4THREADS_BEGIN_N : must be >= 512, default=524288


-------- Complex DFT (Discrete Fourier Transform) --------
    [definition]
        <case1>
            X[k] = sum_j=0^n-1 x[j]*exp(2*pi*i*j*k/n), 0<=k<n
        <case2>
            X[k] = sum_j=0^n-1 x[j]*exp(-2*pi*i*j*k/n), 0<=k<n
        (notes: sum_j=0^n-1 is a summation from j=0 to n-1)
    [usage]
        <case1>
            ip[0] = 0; // first time only
            cdft(2*n, 1, a, ip, w);
        <case2>
            ip[0] = 0; // first time only
            cdft(2*n, -1, a, ip, w);
    [parameters]
        2*n            :data length (int)
                        n >= 1, n = power of 2
        a[0...2*n-1]   :input/output data (double *)
                        input data
                            a[2*j] = Re(x[j]), 
                            a[2*j+1] = Im(x[j]), 0<=j<n
                        output data
                            a[2*k] = Re(X[k]), 
                            a[2*k+1] = Im(X[k]), 0<=k<n
        ip[0...*]      :work area for bit reversal (int *)
                        length of ip >= 2+sqrt(n)
                        strictly, 
                        length of ip >= 
                            2+(1<<(int)(log(n+0.5)/log(2))/2).
                        ip[0],ip[1] are pointers of the cos/sin table.
        w[0...n/2-1]   :cos/sin table (double *)
                        w[],ip[] are initialized if ip[0] == 0.
    [remark]
        Inverse of 
            cdft(2*n, -1, a, ip, w);
        is 
            cdft(2*n, 1, a, ip, w);
            for (j = 0; j <= 2 * n - 1; j++) {
                a[j] *= 1.0 / n;
            }
        .


-------- Real DFT / Inverse of Real DFT --------
    [definition]
        <case1> RDFT
            R[k] = sum_j=0^n-1 a[j]*cos(2*pi*j*k/n), 0<=k<=n/2
            I[k] = sum_j=0^n-1 a[j]*sin(2*pi*j*k/n), 0<k<n/2
        <case2> IRDFT (excluding scale)
            a[k] = (R[0] + R[n/2]*cos(pi*k))/2 + 
                   sum_j=1^n/2-1 R[j]*cos(2*pi*j*k/n) + 
                   sum_j=1^n/2-1 I[j]*sin(2*pi*j*k/n), 0<=k<n
    [usage]
        <case1>
            ip[0] = 0; // first time only
            rdft(n, 1, a, ip, w);
        <case2>
            ip[0] = 0; // first time only
            rdft(n, -1, a, ip, w);
    [parameters]
        n              :data length (int)
                        n >= 2, n = power of 2
        a[0...n-1]     :input/output data (double *)
                        <case1>
                            output data
                                a[2*k] = R[k], 0<=k<n/2
                                a[2*k+1] = I[k], 0<k<n/2
                                a[1] = R[n/2]
                        <case2>
                            input data
                                a[2*j] = R[j], 0<=j<n/2
                                a[2*j+1] = I[j], 0<j<n/2
                                a[1] = R[n/2]
        ip[0...*]      :work area for bit reversal (int *)
                        length of ip >= 2+sqrt(n/2)
                        strictly, 
                        length of ip >= 
                            2+(1<<(int)(log(n/2+0.5)/log(2))/2).
                        ip[0],ip[1] are pointers of the cos/sin table.
        w[0...n/2-1]   :cos/sin table (double *)
                        w[],ip[] are initialized if ip[0] == 0.
    [remark]
        Inverse of 
            rdft(n, 1, a, ip, w);
        is 
            rdft(n, -1, a, ip, w);
            for (j = 0; j <= n - 1; j++) {
                a[j] *= 2.0 / n;
            }
        .


-------- DCT (Discrete Cosine Transform) / Inverse of DCT --------
    [definition]
        <case1> IDCT (excluding scale)
            C[k] = sum_j=0^n-1 a[j]*cos(pi*j*(k+1/2)/n), 0<=k<n
        <case2> DCT
            C[k] = sum_j=0^n-1 a[j]*cos(pi*(j+1/2)*k/n), 0<=k<n
    [usage]
        <case1>
            ip[0] = 0; // first time only
            ddct(n, 1, a, ip, w);
        <case2>
            ip[0] = 0; // first time only
            ddct(n, -1, a, ip, w);
    [parameters]
        n              :data length (int)
                        n >= 2, n = power of 2
        a[0...n-1]     :input/output data (double *)
                        output data
                            a[k] = C[k], 0<=k<n
        ip[0...*]      :work area for bit reversal (int *)
                        length of ip >= 2+sqrt(n/2)
                        strictly, 
                        length of ip >= 
                            2+(1<<(int)(log(n/2+0.5)/log(2))/2).
                        ip[0],ip[1] are pointers of the cos/sin table.
        w[0...n*5/4-1] :cos/sin table (double *)
                        w[],ip[] are initialized if ip[0] == 0.
    [remark]
        Inverse of 
            ddct(n, -1, a, ip, w);
        is 
            a[0] *= 0.5;
            ddct(n, 1, a, ip, w);
            for (j = 0; j <= n - 1; j++) {
                a[j] *= 2.0 / n;
            }
        .


-------- DST (Discrete Sine Transform) / Inverse of DST --------
    [definition]
        <case1> IDST (excluding scale)
            S[k] = sum_j=1^n A[j]*sin(pi*j*(k+1/2)/n), 0<=k<n
        <case2> DST
            S[k] = sum_j=0^n-1 a[j]*sin(pi*(j+1/2)*k/n), 0<k<=n
    [usage]
        <case1>
            ip[0] = 0; // first time only
            ddst(n, 1, a, ip, w);
        <case2>
            ip[0] = 0; // first time only
            ddst(n, -1, a, ip, w);
    [parameters]
        n              :data length (int)
                        n >= 2, n = power of 2
        a[0...n-1]     :input/output data (double *)
                        <case1>
                            input data
                                a[j] = A[j], 0<j<n
                                a[0] = A[n]
                            output data
                                a[k] = S[k], 0<=k<n
                        <case2>
                            output data
                                a[k] = S[k], 0<k<n
                                a[0] = S[n]
        ip[0...*]      :work area for bit reversal (int *)
                        length of ip >= 2+sqrt(n/2)
                        strictly, 
                        length of ip >= 
                            2+(1<<(int)(log(n/2+0.5)/log(2))/2).
                        ip[0],ip[1] are pointers of the cos/sin table.
        w[0...n*5/4-1] :cos/sin table (double *)
                        w[],ip[] are initialized if ip[0] == 0.
    [remark]
        Inverse of 
            ddst(n, -1, a, ip, w);
        is 
            a[0] *= 0.5;
            ddst(n, 1, a, ip, w);
            for (j = 0; j <= n - 1; j++) {
                a[j] *= 2.0 / n;
            }
        .


-------- Cosine Transform of RDFT (Real Symmetric DFT) --------
    [definition]
        C[k] = sum_j=0^n a[j]*cos(pi*j*k/n), 0<=k<=n
    [usage]
        ip[0] = 0; // first time only
        dfct(n, a, t, ip, w);
    [parameters]
        n              :data length - 1 (int)
                        n >= 2, n = power of 2
        a[0...n]       :input/output data (double *)
                        output data
                            a[k] = C[k], 0<=k<=n
        t[0...n/2]     :work area (double *)
        ip[0...*]      :work area for bit reversal (int *)
                        length of ip >= 2+sqrt(n/4)
                        strictly, 
                        length of ip >= 
                            2+(1<<(int)(log(n/4+0.5)/log(2))/2).
                        ip[0],ip[1] are pointers of the cos/sin table.
        w[0...n*5/8-1] :cos/sin table (double *)
                        w[],ip[] are initialized if ip[0] == 0.
    [remark]
        Inverse of 
            a[0] *= 0.5;
            a[n] *= 0.5;
            dfct(n, a, t, ip, w);
        is 
            a[0] *= 0.5;
            a[n] *= 0.5;
            dfct(n, a, t, ip, w);
            for (j = 0; j <= n; j++) {
                a[j] *= 2.0 / n;
            }
        .


-------- Sine Transform of RDFT (Real Anti-symmetric DFT) --------
    [definition]
        S[k] = sum_j=1^n-1 a[j]*sin(pi*j*k/n), 0<k<n
    [usage]
        ip[0] = 0; // first time only
        dfst(n, a, t, ip, w);
    [parameters]
        n              :data length + 1 (int)
                        n >= 2, n = power of 2
        a[0...n-1]     :input/output data (double *)
                        output data
                            a[k] = S[k], 0<k<n
                        (a[0] is used for work area)
        t[0...n/2-1]   :work area (double *)
        ip[0...*]      :work area for bit reversal (int *)
                        length of ip >= 2+sqrt(n/4)
                        strictly, 
                        length of ip >= 
                            2+(1<<(int)(log(n/4+0.5)/log(2))/2).
                        ip[0],ip[1] are pointers of the cos/sin table.
        w[0...n*5/8-1] :cos/sin table (double *)
                        w[],ip[] are initialized if ip[0] == 0.
    [remark]
        Inverse of 
            dfst(n, a, t, ip, w);
        is 
            dfst(n, a, t, ip, w);
            for (j = 1; j <= n - 1; j++) {
                a[j] *= 2.0 / n;
            }
        .


Appendix :
    The cos/sin table is recalculated when the larger table required.
    w[] and ip[] are compatible with all routines.
*/


void cdft(int n, int isgn, double *a, int *ip, double *w)
{ … }


void rdft(int n, int isgn, double *a, int *ip, double *w)
{ … }


void ddct(int n, int isgn, double *a, int *ip, double *w)
{ … }


void ddst(int n, int isgn, double *a, int *ip, double *w)
{ … }


void dfct(int n, double *a, double *t, int *ip, double *w)
{ … }


void dfst(int n, double *a, double *t, int *ip, double *w)
{ … }


/* -------- initializing routines -------- */


#include <math.h>

void makewt(int nw, int *ip, double *w)
{ … }


void makeipt(int nw, int *ip)
{ … }


void makect(int nc, int *ip, double *c)
{ … }


/* -------- child routines -------- */


#ifdef USE_CDFT_PTHREADS
#define USE_CDFT_THREADS
#ifndef CDFT_THREADS_BEGIN_N
#define CDFT_THREADS_BEGIN_N …
#endif
#ifndef CDFT_4THREADS_BEGIN_N
#define CDFT_4THREADS_BEGIN_N …
#endif
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#define cdft_thread_t …
#define cdft_thread_create …
#define cdft_thread_wait …
#endif /* USE_CDFT_PTHREADS */


#ifdef USE_CDFT_WINTHREADS
#define USE_CDFT_THREADS
#ifndef CDFT_THREADS_BEGIN_N
#define CDFT_THREADS_BEGIN_N …
#endif
#ifndef CDFT_4THREADS_BEGIN_N
#define CDFT_4THREADS_BEGIN_N …
#endif
#include <windows.h>
#include <stdio.h>
#include <stdlib.h>
#define cdft_thread_t …
#define cdft_thread_create …
#define cdft_thread_wait …
#endif /* USE_CDFT_WINTHREADS */


void cftfsub(int n, double *a, int *ip, int nw, double *w)
{ … }


void cftbsub(int n, double *a, int *ip, int nw, double *w)
{ … }


void bitrv2(int n, int *ip, double *a)
{ … }


void bitrv2conj(int n, int *ip, double *a)
{ … }


void bitrv216(double *a)
{ … }


void bitrv216neg(double *a)
{ … }


void bitrv208(double *a)
{ … }


void bitrv208neg(double *a)
{ … }


void cftf1st(int n, double *a, double *w)
{ … }


void cftb1st(int n, double *a, double *w)
{ … }


#ifdef USE_CDFT_THREADS
struct cdft_arg_st {
    int n0;
    int n;
    double *a;
    int nw;
    double *w;
};
typedef struct cdft_arg_st cdft_arg_t;


void cftrec4_th(int n, double *a, int nw, double *w)
{
    void *cftrec1_th(void *p);
    void *cftrec2_th(void *p);
    int i, idiv4, m, nthread;
    cdft_thread_t th[4];
    cdft_arg_t ag[4];
    
    nthread = 2;
    idiv4 = 0;
    m = n >> 1;
    if (n > CDFT_4THREADS_BEGIN_N) {
        nthread = 4;
        idiv4 = 1;
        m >>= 1;
    }
    for (i = 0; i < nthread; i++) {
        ag[i].n0 = n;
        ag[i].n = m;
        ag[i].a = &a[i * m];
        ag[i].nw = nw;
        ag[i].w = w;
        if (i != idiv4) {
            cdft_thread_create(&th[i], cftrec1_th, &ag[i]);
        } else {
            cdft_thread_create(&th[i], cftrec2_th, &ag[i]);
        }
    }
    for (i = 0; i < nthread; i++) {
        cdft_thread_wait(th[i]);
    }
}


void *cftrec1_th(void *p)
{
    int cfttree(int n, int j, int k, double *a, int nw, double *w);
    void cftleaf(int n, int isplt, double *a, int nw, double *w);
    void cftmdl1(int n, double *a, double *w);
    int isplt, j, k, m, n, n0, nw;
    double *a, *w;
    
    n0 = ((cdft_arg_t *) p)->n0;
    n = ((cdft_arg_t *) p)->n;
    a = ((cdft_arg_t *) p)->a;
    nw = ((cdft_arg_t *) p)->nw;
    w = ((cdft_arg_t *) p)->w;
    m = n0;
    while (m > 512) {
        m >>= 2;
        cftmdl1(m, &a[n - m], &w[nw - (m >> 1)]);
    }
    cftleaf(m, 1, &a[n - m], nw, w);
    k = 0;
    for (j = n - m; j > 0; j -= m) {
        k++;
        isplt = cfttree(m, j, k, a, nw, w);
        cftleaf(m, isplt, &a[j - m], nw, w);
    }
    return (void *) 0;
}


void *cftrec2_th(void *p)
{
    int cfttree(int n, int j, int k, double *a, int nw, double *w);
    void cftleaf(int n, int isplt, double *a, int nw, double *w);
    void cftmdl2(int n, double *a, double *w);
    int isplt, j, k, m, n, n0, nw;
    double *a, *w;
    
    n0 = ((cdft_arg_t *) p)->n0;
    n = ((cdft_arg_t *) p)->n;
    a = ((cdft_arg_t *) p)->a;
    nw = ((cdft_arg_t *) p)->nw;
    w = ((cdft_arg_t *) p)->w;
    k = 1;
    m = n0;
    while (m > 512) {
        m >>= 2;
        k <<= 2;
        cftmdl2(m, &a[n - m], &w[nw - m]);
    }
    cftleaf(m, 0, &a[n - m], nw, w);
    k >>= 1;
    for (j = n - m; j > 0; j -= m) {
        k++;
        isplt = cfttree(m, j, k, a, nw, w);
        cftleaf(m, isplt, &a[j - m], nw, w);
    }
    return (void *) 0;
}
#endif /* USE_CDFT_THREADS */


void cftrec4(int n, double *a, int nw, double *w)
{ … }


int cfttree(int n, int j, int k, double *a, int nw, double *w)
{ … }


void cftleaf(int n, int isplt, double *a, int nw, double *w)
{ … }


void cftmdl1(int n, double *a, double *w)
{ … }


void cftmdl2(int n, double *a, double *w)
{ … }


void cftfx41(int n, double *a, int nw, double *w)
{ … }


void cftf161(double *a, double *w)
{ … }


void cftf162(double *a, double *w)
{ … }


void cftf081(double *a, double *w)
{ … }


void cftf082(double *a, double *w)
{ … }


void cftf040(double *a)
{ … }


void cftb040(double *a)
{ … }


void cftx020(double *a)
{ … }


void rftfsub(int n, double *a, int nc, double *c)
{ … }


void rftbsub(int n, double *a, int nc, double *c)
{ … }


void dctsub(int n, double *a, int nc, double *c)
{ … }


void dstsub(int n, double *a, int nc, double *c)
{ … }
chromium/third_party/fft2d/src/fftsg.c
