float_to_half.cuh
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#ifndef STIM_CUDA_FLOAT_TO_HALF_H
#define STIM_CUDA_FLOAT_TO_HALF_H
#include <iostream>
#include <cuda.h>
#include <stim/cuda/cudatools.h>
#include <stim/cuda/sharedmem.cuh>
#include <stim/cuda/cudatools/error.h>
#include <cuda_fp16.h>
#include <stdio.h>
__global__ void cuda_f2h(half* gpu_half, float* gpu_float, int x, int y, int z){
//calculate x,y,z coordinates for this thread
int xi = blockIdx.x * blockDim.x + threadIdx.x;
//find the grid size along y
int grid_y = y / blockDim.y;
int blockidx_y = blockIdx.y % grid_y;
int yi = blockidx_y * blockDim.y + threadIdx.y;
int zi = blockIdx.y / grid_y;
int i = zi * x * y + yi * x + xi;
if(xi >= x|| yi >= y || zi>= z) return;
gpu_half[i] = __float2half(gpu_float[i]);
}
void gpu_f2h(half* gpu_half, float* gpu_float, unsigned int x, unsigned int y, unsigned int z){
int max_threads = stim::maxThreadsPerBlock();
dim3 threads(sqrt (max_threads),sqrt (max_threads));
dim3 blocks(x / threads.x + 1, (y / threads.y + 1) * z);
//call the GPU kernel to determine the gradient
cuda_f2h <<< blocks, threads >>>(gpu_half, gpu_float, x, y, z);
}
void cpu_f2h(half* h_out, float* f_in, unsigned int x, unsigned int y, unsigned int z){
//calculate the number of pixels in the array
unsigned int pix = x* y* z;
//allocate memory on the GPU for the input float precision.
float* gpu_float;
cudaMalloc(&gpu_float, pix * sizeof(float));
cudaMemcpy(gpu_float, f_in, pix * sizeof(float), cudaMemcpyHostToDevice);
//allocate memory on the GPU for the output half precision
half* gpu_half;
cudaMalloc(&gpu_half, pix * sizeof(half));
//call the GPU version of this function
gpu_f2h(gpu_half, gpu_float, x, y, z);
//copy the array back to the CPU
cudaMemcpy(h_out, gpu_half, pix * sizeof(half), cudaMemcpyDeviceToHost);
//free allocated memory
cudaFree(gpu_float);
cudaFree(gpu_half);
}
#endif