cuda-samples/Samples/0_Introduction/simpleTemplates/sharedmem.cuh

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#ifndef _SHAREDMEM_H_
#define _SHAREDMEM_H_

//****************************************************************************
// Because dynamically sized shared memory arrays are declared "extern",
// we can't templatize them directly.  To get around this, we declare a
// simple wrapper struct that will declare the extern array with a different
// name depending on the type.  This avoids compiler errors about duplicate
// definitions.
//
// To use dynamically allocated shared memory in a templatized __global__ or
// __device__ function, just replace code like this:
//
//
//  template<class T>
//  __global__ void
//  foo( T* g_idata, T* g_odata)
//  {
//      // Shared mem size is determined by the host app at run time
//      extern __shared__  T sdata[];
//      ...
//      doStuff(sdata);
//      ...
//   }
//
//   With this
//  template<class T>
//  __global__ void
//  foo( T* g_idata, T* g_odata)
//  {
//      // Shared mem size is determined by the host app at run time
//      SharedMemory<T> smem;
//      T* sdata = smem.getPointer();
//      ...
//      doStuff(sdata);
//      ...
//   }
//****************************************************************************

// This is the un-specialized struct.  Note that we prevent instantiation of
// this
// struct by putting an undefined symbol in the function body so it won't
// compile.
template <typename T>
struct SharedMemory {
  // Ensure that we won't compile any un-specialized types
  __device__ T *getPointer() {
    extern __device__ void error(void);
    error();
    return NULL;
  }
};

// Following are the specializations for the following types.
// int, uint, char, uchar, short, ushort, long, ulong, bool, float, and double
// One could also specialize it for user-defined types.

template <>
struct SharedMemory<int> {
  __device__ int *getPointer() {
    extern __shared__ int s_int[];
    return s_int;
  }
};

template <>
struct SharedMemory<unsigned int> {
  __device__ unsigned int *getPointer() {
    extern __shared__ unsigned int s_uint[];
    return s_uint;
  }
};

template <>
struct SharedMemory<char> {
  __device__ char *getPointer() {
    extern __shared__ char s_char[];
    return s_char;
  }
};

template <>
struct SharedMemory<unsigned char> {
  __device__ unsigned char *getPointer() {
    extern __shared__ unsigned char s_uchar[];
    return s_uchar;
  }
};

template <>
struct SharedMemory<short> {
  __device__ short *getPointer() {
    extern __shared__ short s_short[];
    return s_short;
  }
};

template <>
struct SharedMemory<unsigned short> {
  __device__ unsigned short *getPointer() {
    extern __shared__ unsigned short s_ushort[];
    return s_ushort;
  }
};

template <>
struct SharedMemory<long> {
  __device__ long *getPointer() {
    extern __shared__ long s_long[];
    return s_long;
  }
};

template <>
struct SharedMemory<unsigned long> {
  __device__ unsigned long *getPointer() {
    extern __shared__ unsigned long s_ulong[];
    return s_ulong;
  }
};

template <>
struct SharedMemory<bool> {
  __device__ bool *getPointer() {
    extern __shared__ bool s_bool[];
    return s_bool;
  }
};

template <>
struct SharedMemory<float> {
  __device__ float *getPointer() {
    extern __shared__ float s_float[];
    return s_float;
  }
};

template <>
struct SharedMemory<double> {
  __device__ double *getPointer() {
    extern __shared__ double s_double[];
    return s_double;
  }
};

#endif  //_SHAREDMEM_H_