I am trying to use a 1D texture as a lookup table. I am setting cudaAddressModeBorder so that values out of range return 0, but that is not what I am getting. What am I doing wrong?

Here is a simple version of the code:

#include

float2 *lookUpTableData;

cudaArray *lookUpTable;

texture<float2, cudaTextureType1D, cudaReadModeElementType> texRef;

**global** void InitializeLookupTables(float2 *lookUpTableData)

{

int position = blockIdx.x * blockDim.x + threadIdx.x;

lookUpTableData[position].x = 2.0f * threadIdx.x;

lookUpTableData[position].y = 4.0f * threadIdx.x;

return;

}

**global** void TestLookupTables()

{

float2 lookUpTableValues;

for (int i=0; i<15; i++) {

lookUpTableValues = tex1D(texRef, 5.0f * i + 0.5f);

printf(“The value returned for value %d is %f.\n”, 5*i, lookUpTableValues.x);

}

}

int main() {

size_t lookUpTable_width = 51;

size_t lookUpTable_size = size_t (sizeof(float2) * lookUpTable_width);

cudaMalloc((void**) &lookUpTableData, lookUpTable_size);

```
cudaChannelFormatDesc channelDesc = cudaCreateChannelDesc<float2>();
cudaExtent length = make_cudaExtent(lookUpTable_width, 0, 0);
cudaMalloc3DArray(&lookUpTable, &channelDesc, length, cudaArrayDefault);
InitializeLookupTables<<<1, 51>>>(lookUpTableData);
cudaDeviceSynchronize();
cudaMemcpyToArray(lookUpTable, 0, 0, lookUpTableData, lookUpTable_size, cudaMemcpyDeviceToDevice);
texRef.addressMode[0] = cudaAddressModeBorder;
texRef.filterMode = cudaFilterModeLinear;
texRef.normalized = false;
cudaBindTextureToArray(texRef, lookUpTable, channelDesc);
TestLookupTables<<<1, 1>>>();
cudaDeviceSynchronize();
return 0;
```

}

I also tried replacing the two lines

```
cudaExtent length = make_cudaExtent(lookUpTable_width, 0, 0);
cudaMalloc3DArray(&lookUpTable, &channelDesc, length, cudaArrayDefault);
```

with

```
cudaMallocArray(&lookUpTable, &channelDesc, lookUpTable_width, 0, cudaArrayDefault);
```

but get the same output.

Here is the output I get when running the program. I was expecting all values greater than 50 to print 0.0, not 100.

The value returned for value 0 is 0.000000.

The value returned for value 5 is 10.000000.

The value returned for value 10 is 20.000000.

The value returned for value 15 is 30.000000.

The value returned for value 20 is 40.000000.

The value returned for value 25 is 50.000000.

The value returned for value 30 is 60.000000.

The value returned for value 35 is 70.000000.

The value returned for value 40 is 80.000000.

The value returned for value 45 is 90.000000.

The value returned for value 50 is 100.000000.

The value returned for value 55 is 100.000000.

The value returned for value 60 is 100.000000.

The value returned for value 65 is 100.000000.

The value returned for value 70 is 100.000000.