#include "mat_mul.h"

#include <cstdio>
#include <cuda_runtime.h>

#define CUDA_CALL(f)                                                           \
  {                                                                            \
    cudaError_t err = (f);                                                     \
    if (err != cudaSuccess) {                                                  \
      fprintf(stderr, "CUDA error at [%s:%d] %d %s\n", __FILE__, __LINE__,     \
              err, cudaGetErrorString(err));                                   \
      exit(1);                                                                 \
    }                                                                          \
  }
#define MAX_NUM_GPU 4
#define TS 32
#define WPT 8
#define RTS (TS/WPT)

int num_devices = 4;   

__global__ void sgemm(float *A, float *B, float *C, int M, int N, int K) {
  /*
  int i = blockDim.x * blockIdx.x + threadIdx.x;
  int j = blockDim.y * blockIdx.y + threadIdx.y;
  */
  
  int row = threadIdx.x;
  //printf("Row = %d\n", row);
  int col = threadIdx.y;
  int globalRow = (blockDim.x*WPT) * blockIdx.x + threadIdx.x;
  int globalCol = blockDim.y * blockIdx.y + threadIdx.y;  
  __shared__ float Asub[TS][TS];
  __shared__ float Bsub[TS][TS];
  
  float acc[WPT];
    for (int w=0; w<WPT; w++) {
       acc[w] = 0.0f;
    }

    const int numTiles = (K+TS-1)/TS;
	//printf("Row1111 = %d\n", row);
    for (int t=0; t<numTiles; t++) {
 
         for (int w=0; w<WPT; w++) {
             const int tiledRow = TS*t + row;
		//	 printf("tileRow = %d\n", tiledRow);
             const int tiledCol = TS*t + col;
			 if(globalRow + w*RTS >= M || tiledCol >= K)
			 {
			 Asub[row + w*RTS][col] = 0.0f;   
			 } 
			 else
			 {
             Asub[row + w*RTS][col] = A[(globalRow + w*RTS)*K + tiledCol];
			 }
			 if(tiledRow + w*RTS >=K || globalCol >=N)
			 {
			 Bsub[row + w*RTS][col] = 0.0f;
			 }
			 else
			 {
             Bsub[row + w*RTS][col] = B[(tiledRow + w*RTS)*N + globalCol];
			 }
         }

		 __syncthreads();
 
        for (int k=0; k<TS; k++) {
            for (int w=0; w<WPT; w++) {
                 acc[w] += Asub[row + w*RTS][k] * Bsub[k][col];
             }
         }

        __syncthreads();
     }
 
     for (int w=0; w<WPT; w++) {
	     if (globalRow + w*RTS >= M || globalCol >=N) continue;
         C[(globalRow + w*RTS)*N + globalCol] = acc[w];
     }
 
}

static float *a_d[MAX_NUM_GPU];
static float *b_d[MAX_NUM_GPU];
static float *c_d[MAX_NUM_GPU];
static int M, N, K;
static int Mbegin[MAX_NUM_GPU], Mend[MAX_NUM_GPU];

void mat_mul(float *_A, float *_B, float *_C, int _M, int _N, int _K) {

  for (int i = 0; i < num_devices; i++) {
    dim3 blockDim(TS/WPT, TS, 1);
    dim3 gridDim(((Mend[i] - Mbegin[i]+TS-1)/TS), (N+TS-1)/TS, 1);
   

    CUDA_CALL( cudaSetDevice(i) );
	sgemm<<<gridDim, blockDim>>>(a_d[i], b_d[i], c_d[i], Mend[i] - Mbegin[i], N, K);
  }

  for (int i = 0; i < num_devices; i++) {
	CUDA_CALL( cudaSetDevice(i) ); 
    CUDA_CALL( cudaDeviceSynchronize() );
  }
}


void mat_mul_init(float *A, float *B, float *C, int _M, int _N, int _K) {
  M = _M, N = _N, K = _K;

  CUDA_CALL( cudaGetDeviceCount(&num_devices) ); 

  printf("Using %d devices\n", num_devices);
  for (int i = 0; i < num_devices; i++) {
    cudaDeviceProp prop;
    CUDA_CALL( cudaGetDeviceProperties(&prop, i) );  

    printf("[GPU %d] %s\n", i, prop.name);
  }
   

  if (num_devices <= 0) {
    printf("No CUDA device found. Aborting\n");
    exit(1);
  }

  for (int i = 0; i < num_devices; i++) {
    Mbegin[i] = (M / num_devices) * i;
    Mend[i] = (M / num_devices) * (i + 1);
  }
  Mend[num_devices - 1] = M;
 

  for (int i = 0; i < num_devices; i++) {
    CUDA_CALL( cudaSetDevice(i) );   
    CUDA_CALL( cudaMalloc(&a_d[i], (Mend[i] - Mbegin[i]) * K * sizeof(float)) );
    CUDA_CALL( cudaMalloc(&b_d[i], K * N * sizeof(float)) );
    CUDA_CALL( cudaMalloc(&c_d[i], (Mend[i] - Mbegin[i]) * N * sizeof(float)) );
  }

  for (int i = 0; i < num_devices; i++) {
    CUDA_CALL( cudaMemcpy(a_d[i], A + Mbegin[i] * K,(Mend[i] - Mbegin[i]) * K * sizeof(float), cudaMemcpyHostToDevice));
    CUDA_CALL( cudaMemcpy(b_d[i], B, K * N * sizeof(float), cudaMemcpyHostToDevice) ); 
  }

  for (int i = 0; i < num_devices; i++) {
    CUDA_CALL( cudaSetDevice(i) );  
    CUDA_CALL( cudaDeviceSynchronize() );
  }
}

void mat_mul_final(float *A, float *B, float *C, int M, int N, int K) {

  for (int i = 0; i < num_devices; i++) {
    CUDA_CALL( cudaMemcpy(C + Mbegin[i] * N, c_d[i],(Mend[i] - Mbegin[i]) * N * sizeof(float), cudaMemcpyDeviceToHost));   
  }

  for (int i = 0; i < num_devices; i++) {
	CUDA_CALL( cudaSetDevice(i) );  
    CUDA_CALL( cudaDeviceSynchronize() );
  }
}