// super super slow sgemm kernel by heehoon
#define TS 32
#define WPT 32
#define RTS 1

#define PADDINGX TS
#define PADDINGY TS

#define MIN(a, b) ((a) < (b) ? (a) : (b))

__kernel void sgemm(__global float *A, __global float *B, __global float *C, int M, int N, int K) {
    const int row = get_local_id(0);
    const int col = get_local_id(1);
    const int global_row = TS * get_group_id(0) + row;
    const int global_col = TS * get_group_id(1) + col;

    __local float Asub[TS][TS];
    __local float Bsub[TS][TS];

    float Csub[WPT];
    for (int w = 0; w < WPT; w++) {
        Csub[w] = 0.0f;
    }

    const int num_tiles = (K  + TS - 1) / TS;

    for (int t = 0; t < num_tiles; t++) {
        #pragma unroll
	    for (int w = 0; w < WPT; w++) {
            const int t_row = TS * t + row;
            const int t_col = TS * t + col;
            Asub[row + w*RTS][col] = A[(global_row + w*RTS) * K + t_col];
            Bsub[row + w*RTS][col] = B[(t_row + w*RTS) * N + global_col];
        }

        barrier(CLK_LOCAL_MEM_FENCE);

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

        barrier(CLK_LOCAL_MEM_FENCE);
    }

    #pragma unroll
    for (int w = 0; w < WPT; w++) {
        C[(global_row + w*RTS) * N + global_col] = Csub[w];
    }
}

// Pad the P * Q matrix with zeroes to form a P_XL * Q_XL matrix
__kernel void paddingAddZeroes(const int P, const int Q,
                               const __global float* input,
                               const int P_XL, const int Q_XL,
                               __global float* output) {

    const int tx = get_group_id(0) * PADDINGX + get_local_id(0);
    const int ty = get_group_id(1) * PADDINGY + get_local_id(1);

    // Check whether we are within bounds of the XL matrix
    if (tx < P_XL && ty < Q_XL) {

        // Copy the input or pad a zero
        float value;
        if (tx < P && ty < Q) {
            value = input[tx*Q + ty];
        }
        else {
            value = 0.0f;
        }

        output[tx*Q_XL + ty] = value;
    }
}

// Remove padded values from a P_XL * Q_XL matrix to form a P * Q matrix
__kernel void paddingRemoveZeroes(const int P_XL, const int Q_XL,
                                  const __global float* input,
                                  const int P, const int Q,
                                  __global float* output) {

    const int tx = get_group_id(0) * PADDINGX + get_local_id(0);
    const int ty = get_group_id(1) * PADDINGY + get_local_id(1);

    // Only store the result if within P * Q bounds
    if (tx < P && ty < Q) {
        output[tx*Q + ty] = input[tx*Q_XL + ty];
    }
}