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#ifndef TH_GENERIC_FILE
#define TH_GENERIC_FILE "generic/SpatialMaxPooling.c"
#else
static void nn_(SpatialMaxPooling_updateOutput_frame)(real *input_p, real *output_p,
real *indx_p, real *indy_p,
long nslices,
long iwidth, long iheight,
long owidth, long oheight,
int kW, int kH, int dW, int dH)
{
long k;
#pragma omp parallel for private(k)
for (k = 0; k < nslices; k++)
{
// loop over output
long i, j;
for(i = 0; i < oheight; i++)
{
for(j = 0; j < owidth; j++)
{
// local pointers
real *ip = input_p + k*iwidth*iheight + i*iwidth*dH + j*dW;
real *op = output_p + k*owidth*oheight + i*owidth + j;
real *indyp = indy_p + k*owidth*oheight + i*owidth + j;
real *indxp = indx_p + k*owidth*oheight + i*owidth + j;
// compute local max:
long maxindex = -1;
real maxval = -THInf;
long tcntr = 0;
int x,y;
for(y = 0; y < kH; y++)
{
for(x = 0; x < kW; x++)
{
real val = *(ip + y*iwidth + x);
if (val > maxval)
{
maxval = val;
maxindex = tcntr;
}
tcntr++;
}
}
// set output to local max
*op = maxval;
// store location of max (x,y)
*indyp = (int)(maxindex / kW)+1;
*indxp = (maxindex % kW) +1;
}
}
}
}
static int nn_(SpatialMaxPooling_updateOutput)(lua_State *L)
{
THTensor *input = luaT_checkudata(L, 2, torch_Tensor);
int kW = luaT_getfieldcheckint(L, 1, "kW");
int kH = luaT_getfieldcheckint(L, 1, "kH");
int dW = luaT_getfieldcheckint(L, 1, "dW");
int dH = luaT_getfieldcheckint(L, 1, "dH");
THTensor *indices = luaT_getfieldcheckudata(L, 1, "indices", torch_Tensor);
THTensor *output = luaT_getfieldcheckudata(L, 1, "output", torch_Tensor);
luaL_argcheck(L, input->nDimension == 3 || input->nDimension == 4 , 2, "3D or 4D (batch mode) tensor expected");
int dimw = 2;
int dimh = 1;
long nbatch = 1;
if (input->nDimension == 4)
{
nbatch = input->size[0];
dimw++;
dimh++;
}
luaL_argcheck(L, input->size[dimw] >= kW && input->size[dimh] >= kH, 2, "input image smaller than kernel size");
// sizes
long nslices = input->size[dimh-1];
long iheight = input->size[dimh];
long iwidth = input->size[dimw];
long oheight = (iheight - kH) / dH + 1;
long owidth = (iwidth - kW) / dW + 1;
// get contiguous input
input = THTensor_(newContiguous)(input);
// resize output
if (input->nDimension == 3)
{
THTensor_(resize3d)(output, nslices, oheight, owidth);
// indices will contain i,j locations for each output point
THTensor_(resize4d)(indices, 2, nslices, oheight, owidth);
real *input_data = THTensor_(data)(input);
real *output_data = THTensor_(data)(output);
real *indices_data = THTensor_(data)(indices);
nn_(SpatialMaxPooling_updateOutput_frame)(input_data, output_data,
indices_data+nslices*owidth*oheight, indices_data,
nslices,
iwidth, iheight,
owidth, oheight,
kW, kH, dW, dH);
}
else
{
THTensor_(resize4d)(output, nbatch, nslices, oheight, owidth);
// indices will contain i,j locations for each output point
THTensor_(resize5d)(indices, 2, nbatch, nslices, oheight, owidth);
real *input_data = THTensor_(data)(input);
real *output_data = THTensor_(data)(output);
real *indices_data = THTensor_(data)(indices);
long p;
#pragma omp parallel for private(p)
for (p = 0; p < nbatch; p++)
{
nn_(SpatialMaxPooling_updateOutput_frame)(input_data+p*nslices*iwidth*iheight, output_data+p*nslices*owidth*oheight,
indices_data+(p+nbatch)*nslices*owidth*oheight, indices_data+p*nslices*owidth*oheight,
nslices,
iwidth, iheight,
owidth, oheight,
kW, kH, dW, dH);
}
}
// cleanup
THTensor_(free)(input);
return 1;
}
static void nn_(SpatialMaxPooling_updateGradInput_frame)(real *gradInput_p, real *gradOutput_p,
real *indx_p, real *indy_p,
long nslices,
long iwidth, long iheight,
long owidth, long oheight,
int dW, int dH)
{
long k;
#pragma omp parallel for private(k)
for (k = 0; k < nslices; k++)
{
real *gradInput_p_k = gradInput_p + k*iwidth*iheight;
real *gradOutput_p_k = gradOutput_p + k*owidth*oheight;
real *indx_p_k = indx_p + k*owidth*oheight;
real *indy_p_k = indy_p + k*owidth*oheight;
// calculate max points
long i, j;
for(i = 0; i < oheight; i++)
{
for(j = 0; j < owidth; j++)
{
// retrieve position of max
long maxi = indy_p_k[i*owidth + j] - 1 + i*dH;
long maxj = indx_p_k[i*owidth + j] - 1 + j*dW;
// update gradient
gradInput_p_k[maxi*iwidth + maxj] += gradOutput_p_k[i*owidth + j];
}
}
}
}
static int nn_(SpatialMaxPooling_updateGradInput)(lua_State *L)
{
THTensor *input = luaT_checkudata(L, 2, torch_Tensor);
THTensor *gradOutput = luaT_checkudata(L, 3, torch_Tensor);
int dW = luaT_getfieldcheckint(L, 1, "dW");
int dH = luaT_getfieldcheckint(L, 1, "dH");
THTensor *indices = luaT_getfieldcheckudata(L, 1, "indices", torch_Tensor);
THTensor *gradInput = luaT_getfieldcheckudata(L, 1, "gradInput", torch_Tensor);
// get contiguous gradOutput
gradOutput = THTensor_(newContiguous)(gradOutput);
// resize
THTensor_(resizeAs)(gradInput, input);
THTensor_(zero)(gradInput);
int dimw = 2;
int dimh = 1;
long nbatch = 1;
if (input->nDimension == 4) {
nbatch = input->size[0];
dimw++;
dimh++;
}
// sizes
int nslices = input->size[dimh-1];
int iheight = input->size[dimh];
int iwidth = input->size[dimw];
int oheight = gradOutput->size[dimh];
int owidth = gradOutput->size[dimw];
// get raw pointers
real *gradInput_data = THTensor_(data)(gradInput);
real *gradOutput_data = THTensor_(data)(gradOutput);
real *indices_data = THTensor_(data)(indices);
// backprop
if (input->nDimension == 3)
{
nn_(SpatialMaxPooling_updateGradInput_frame)(gradInput_data, gradOutput_data,
indices_data+nslices*owidth*oheight, indices_data,
nslices,
iwidth, iheight,
owidth, oheight,
dW, dH);
}
else
{
long p;
#pragma omp parallel for private(p)
for (p = 0; p < nbatch; p++)
{
nn_(SpatialMaxPooling_updateGradInput_frame)(gradInput_data+p*nslices*iwidth*iheight, gradOutput_data+p*nslices*owidth*oheight,
indices_data+(p+nbatch)*nslices*owidth*oheight, indices_data+p*nslices*owidth*oheight,
nslices,
iwidth, iheight,
owidth, oheight,
dW, dH);
}
}
// cleanup
THTensor_(free)(gradOutput);
return 1;
}
static const struct luaL_Reg nn_(SpatialMaxPooling__) [] = {
{"SpatialMaxPooling_updateOutput", nn_(SpatialMaxPooling_updateOutput)},
{"SpatialMaxPooling_updateGradInput", nn_(SpatialMaxPooling_updateGradInput)},
{NULL, NULL}
};
static void nn_(SpatialMaxPooling_init)(lua_State *L)
{
luaT_pushmetatable(L, torch_Tensor);
luaT_registeratname(L, nn_(SpatialMaxPooling__), "nn");
lua_pop(L,1);
}
#endif
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