指向WebAssembly的数组的JavaScript数组
我目前正在尝试实现JavaScript数组的2D FFT。虽然在JS中是可行的,但矩阵通常足够大(例如3000x4000),这使得它有点慢。我考虑用C语言实现2D FFT,并使用WebAssembly来加速 2D FFT实现源于。我做了一些修改,在不同的指针中有实值和虚值。我将代码粘贴到这里:指向WebAssembly的数组的JavaScript数组,javascript,c,pointers,webassembly,emscripten,Javascript,C,Pointers,Webassembly,Emscripten,我目前正在尝试实现JavaScript数组的2D FFT。虽然在JS中是可行的,但矩阵通常足够大(例如3000x4000),这使得它有点慢。我考虑用C语言实现2D FFT,并使用WebAssembly来加速 2D FFT实现源于。我做了一些修改,在不同的指针中有实值和虚值。我将代码粘贴到这里: /*------------------------------------------------------------------------- Perform a 2D FFT inplace g
/*-------------------------------------------------------------------------
Perform a 2D FFT inplace given a complex 2D array
The direction dir, 1 for forward, -1 for reverse
The size of the array (nx,ny)
*/
#include <stdlib.h>
#include <math.h>
/* This computes an in-place complex-to-complex FFT */
int FFT(int dir,int m, double *x,double *y)
{
long nn,i,i1,j,k,i2,l,l1,l2;
double c1,c2,tx,ty,t1,t2,u1,u2,z;
/* Calculate the number of points */
nn = 1;
for (i=0;i<m;i++)
nn *= 2;
/* Do the bit reversal */
i2 = nn >> 1;
j = 0;
for (i=0;i<nn-1;i++) {
if (i < j) {
tx = x[i];
ty = y[i];
x[i] = x[j];
y[i] = y[j];
x[j] = tx;
y[j] = ty;
}
k = i2;
while (k <= j) {
j -= k;
k >>= 1;
}
j += k;
}
/* Compute the FFT */
c1 = -1.0;
c2 = 0.0;
l2 = 1;
for (l=0;l<m;l++) {
l1 = l2;
l2 <<= 1;
u1 = 1.0;
u2 = 0.0;
for (j=0;j<l1;j++) {
for (i=j;i<nn;i+=l2) {
i1 = i + l1;
t1 = u1 * x[i1] - u2 * y[i1];
t2 = u1 * y[i1] + u2 * x[i1];
x[i1] = x[i] - t1;
y[i1] = y[i] - t2;
x[i] += t1;
y[i] += t2;
}
z = u1 * c1 - u2 * c2;
u2 = u1 * c2 + u2 * c1;
u1 = z;
}
c2 = sqrt((1.0 - c1) / 2.0);
if (dir == 1)
c2 = -c2;
c1 = sqrt((1.0 + c1) / 2.0);
}
/* Scaling for forward transform */
if (dir == 1) {
for (i=0;i<nn;i++) {
x[i] /= (double)nn;
y[i] /= (double)nn;
}
}
return 0;
}
int FFT2D(double **c_real, double **c_imag, int nx, int ny, int dir)
{
int i,j,m;
double *real,*imag;
/* Transform the rows */
real = (double *)malloc(nx * sizeof(double));
imag = (double *)malloc(nx * sizeof(double));
m = log(nx)/log(2);
for (j=0;j<ny;j++) {
for (i=0;i<nx;i++) {
real[i] = c_real[j][i];
imag[i] = c_imag[j][i];
}
FFT(dir,m,real,imag);
for (i=0;i<nx;i++) {
c_real[j][i] = real[i];
c_imag[j][i] = imag[i];
}
}
free(real);
free(imag);
/* Transform the columns */
real = (double *)malloc(ny * sizeof(double));
imag = (double *)malloc(ny * sizeof(double));
m = log(ny)/log(2);
for (i=0;i<nx;i++) {
for (j=0;j<ny;j++) {
real[j] = c_real[j][i];
imag[j] = c_imag[j][i];
}
FFT(dir,m,real,imag);
for (j=0;j<ny;j++) {
c_real[j][i] = real[j];
c_imag[j][i] = imag[j];
}
}
free(real);
free(imag);
return 0;
}
int HL_2DFFT(double **real, double **imag, double **real_ptr, double **imag_ptr, int nx, int ny, int nx_pw2, int ny_pw2){
int i, j, diff_nx, diff_ny;
diff_nx = nx_pw2 - nx;
diff_ny = ny_pw2 - ny;
// copy matrix and expand to power of 2.
for (i = diff_ny/2; i < ny; ++i) {
for (j = 0; j < nx_pw2; ++j) {
if(j<diff_nx/2){
real_ptr[i][j] = real[i-(diff_ny/2)][0];
imag_ptr[i][j] = imag[i-(diff_ny/2)][0];
}
else if(j>(diff_nx/2 - 1) && j<nx){
real_ptr[i][j] = real[i-(diff_ny/2)][j-(diff_nx/2)];
imag_ptr[i][j] = imag[i-(diff_ny/2)][j-(diff_ny/2)];
} else{
real_ptr[i][j] = real[i-(diff_ny/2)][nx-1];
imag_ptr[i][j] = imag[i-(diff_ny/2)][nx-1];
}
}
};
// Top padding
for(i=0; i<diff_ny/2;++i){
for (j = 0; j < nx_pw2; ++j) {
real_ptr[i][j] = real_ptr[diff_ny/2][j];
imag_ptr[i][j] = imag_ptr[diff_ny/2][j];
};
};
// Bottom padding
for(i=ny; i<ny_pw2;++i){
for (j = 0; j < nx_pw2; ++j) {
real_ptr[i][j] = real_ptr[ny-1][j];
imag_ptr[i][j] = imag_ptr[ny-1][j];
};
};
FFT2D(real_ptr, imag_ptr, nx_pw2, ny_pw2, 1);
return 0;
}
JS中的数组数组作为变量数据。hl_2dfft函数返回一个错误,表示:
未捕获运行时错误:内存访问超出界限
任何帮助都将不胜感激 对于任何感兴趣的人来说,我找不到任何和如何将指针指针传递给WASM有关的东西,而且到目前为止,我可以尝试的任何东西都不起作用。现在,我已经实现了0给出的解决方案,即展平JS数组(使用下面的展平函数)并向WASM传递一个指针
const flatten = function(arr, result = []) {
for (let i = 0, length = arr.length; i < length; i++) {
const value = arr[i];
if (Array.isArray(value)) {
flatten(value, result)
} else {
result.push(value)
}
};
return result;
};
const flatte=函数(arr,result=[]){
for(设i=0,length=arr.length;i
如果将大型数组作为数组数组存储在JS中,那么这会带来一些不便,需要花费一些时间来线性化它们,但是在JS端创建指针指针似乎并不简单。如果有人知道解决方法,那就太好了。对于任何感兴趣的人来说,我找不到任何与如何将指针指针传递给WASM相关的内容,我可以尝试的任何内容到目前为止都不起作用。现在,我已经实现了0给出的解决方案,即展平JS数组(使用下面的展平函数)并向WASM传递一个指针
const flatten = function(arr, result = []) {
for (let i = 0, length = arr.length; i < length; i++) {
const value = arr[i];
if (Array.isArray(value)) {
flatten(value, result)
} else {
result.push(value)
}
};
return result;
};
const flatte=函数(arr,result=[]){
for(设i=0,length=arr.length;i
如果将大型数组作为数组数组存储在JS中,那么这会带来一些不便,需要花费一些时间来线性化它们,但是在JS端创建指针指针似乎并不简单。如果有人知道一个变通方法,那就太好了。作为变通方法,你可以让你的2D函数采用大小为
nx*ny
的1D“平面数组”,而只需用c_real[j][i]
替换为c_real[j*nx+i]
作为变通方法,你可以让你的2D函数采用1D“平面数组”大小为nx*ny
,只需将c_real[j][i]
替换为c_real[j*nx+i]