#include "common.cuh"
#include "mmv.cuh"

template <typename type_acc, int block_size>
static __global__ void mul_mat_vec(
        const half * __restrict__ x, const float * __restrict__ y, float * __restrict__ dst, const int64_t ncols2, const int64_t stride_row,
        const int64_t channel_ratio, const int64_t stride_channel_x, const int64_t stride_channel_y, const int64_t stride_channel_dst) {
    const int64_t row     = blockIdx.x;
    const int64_t channel = blockIdx.z;
    const int     tid     = threadIdx.x;

    x   += (channel/channel_ratio)*stride_channel_x + row*stride_row;
    y   +=  channel               *stride_channel_y;
    dst +=  channel               *stride_channel_dst;

    const half2  * x2 = (const half2  *) x;
    const float2 * y2 = (const float2 *) y;

    extern __shared__ char data_mmv[];
    float * buf_iw = (float *) data_mmv;

    if (block_size > WARP_SIZE) {
        if (tid < WARP_SIZE) {
            buf_iw[tid] = 0.0f;
        }
        __syncthreads();
    }

    float sumf;

    if (std::is_same<type_acc, float>::value) {
        sumf = 0.0f;

        for (int64_t col2 = tid; col2 < ncols2; col2 += block_size) {
            const float2 tmpx = __half22float2(x2[col2]);
            const float2 tmpy = y2[col2];
            sumf += tmpx.x * tmpy.x;
            sumf += tmpx.y * tmpy.y;
        }
    } else {
#ifdef FP16_AVAILABLE
        half2 sumh2 = make_half2(0.0f, 0.0f);

        for (int64_t col2 = tid; col2 < ncols2; col2 += block_size) {
            const float2 tmp = y2[col2];
            sumh2 += x2[col2] * make_half2(tmp.x, tmp.y);
        }

        sumf = __low2float(sumh2) + __high2float(sumh2);
#else
        NO_DEVICE_CODE;
#endif // FP16_AVAILABLE
    }

    sumf = warp_reduce_sum(sumf);

    if (block_size > WARP_SIZE) {
        buf_iw[tid/WARP_SIZE] = sumf;
        __syncthreads();
        if (tid > WARP_SIZE) {
            return;
        }
        sumf = buf_iw[tid];
        sumf = warp_reduce_sum(sumf);
    }

    if (tid != 0) {
        return;
    }

    dst[row] = sumf;
}

template <typename type_acc>
static void launch_mul_mat_vec_cuda(
        const half * x, const float * y, float * dst,
        const int64_t ncols, const int64_t nrows, const int64_t stride_row, const int64_t nchannels_x, const int64_t nchannels_y,
        const int64_t stride_channel_x, const int64_t stride_channel_y, const int64_t stride_channel_dst,
        cudaStream_t stream) {
    GGML_ASSERT(ncols      % 2 == 0);
    GGML_ASSERT(stride_row % 2 == 0);
    GGML_ASSERT(nchannels_y % nchannels_x == 0);
    const int64_t channel_ratio = nchannels_y / nchannels_x;

    int64_t block_size_best = WARP_SIZE;
    int64_t niter_best      = (ncols + 2*WARP_SIZE - 1) / (2*WARP_SIZE);
    for (int64_t block_size = 2*WARP_SIZE; block_size <= 256; block_size += WARP_SIZE) {
        const int64_t niter = (ncols + 2*block_size - 1) / (2*block_size);
        if (niter < niter_best) {
            niter_best      = niter;
            block_size_best = block_size;
        }
    }

    const int smem = WARP_SIZE*sizeof(float);
    const dim3 block_nums(nrows, 1, nchannels_y);
    const dim3 block_dims(block_size_best, 1, 1);
    switch (block_size_best) {
        case   32: {
            mul_mat_vec<type_acc,  32><<<block_nums, block_dims, smem, stream>>>
                (x, y, dst, ncols/2, stride_row, channel_ratio, stride_channel_x, stride_channel_y, stride_channel_dst);
        } break;
        case   64: {
            mul_mat_vec<type_acc,  64><<<block_nums, block_dims, smem, stream>>>
                (x, y, dst, ncols/2, stride_row, channel_ratio, stride_channel_x, stride_channel_y, stride_channel_dst);
        } break;
        case   96: {
            mul_mat_vec<type_acc,  96><<<block_nums, block_dims, smem, stream>>>
                (x, y, dst, ncols/2, stride_row, channel_ratio, stride_channel_x, stride_channel_y, stride_channel_dst);
        } break;
        case  128: {
            mul_mat_vec<type_acc, 128><<<block_nums, block_dims, smem, stream>>>
                (x, y, dst, ncols/2, stride_row, channel_ratio, stride_channel_x, stride_channel_y, stride_channel_dst);
        } break;
        case  160: {
            mul_mat_vec<type_acc, 160><<<block_nums, block_dims, smem, stream>>>
                (x, y, dst, ncols/2, stride_row, channel_ratio, stride_channel_x, stride_channel_y, stride_channel_dst);
        } break;
        case  192: {
            mul_mat_vec<type_acc, 192><<<block_nums, block_dims, smem, stream>>>
                (x, y, dst, ncols/2, stride_row, channel_ratio, stride_channel_x, stride_channel_y, stride_channel_dst);
        } break;
        case  224: {
            mul_mat_vec<type_acc, 224><<<block_nums, block_dims, smem, stream>>>
                (x, y, dst, ncols/2, stride_row, channel_ratio, stride_channel_x, stride_channel_y, stride_channel_dst);
        } break;
        case  256: {
            mul_mat_vec<type_acc, 256><<<block_nums, block_dims, smem, stream>>>
                (x, y, dst, ncols/2, stride_row, channel_ratio, stride_channel_x, stride_channel_y, stride_channel_dst);
        } break;
        default: {
            GGML_ABORT("fatal error");
        } break;
    }
}

static void mul_mat_vec_cuda(
        const half * x, const float * y, float * dst,
        const int64_t ncols, const int64_t nrows, const int64_t stride_row, const int64_t nchannels_x, const int64_t nchannels_y,
        const int64_t stride_channel_x, const int64_t stride_channel_y, const int64_t stride_channel_dst,
        enum ggml_prec prec, cudaStream_t stream) {
    switch (prec) {
        case GGML_PREC_DEFAULT: {
            launch_mul_mat_vec_cuda<half>(x, y, dst, ncols, nrows, stride_row, nchannels_x, nchannels_y,
                stride_channel_x, stride_channel_y, stride_channel_dst, stream);
        } break;
        case GGML_PREC_F32: {
            launch_mul_mat_vec_cuda<float>(x, y, dst, ncols, nrows, stride_row, nchannels_x, nchannels_y,
                stride_channel_x, stride_channel_y, stride_channel_dst, stream);
        } break;
    }
}

void ggml_cuda_mul_mat_vec(ggml_backend_cuda_context & ctx, const ggml_tensor * src0, const ggml_tensor * src1, ggml_tensor * dst) {
    GGML_ASSERT(src0->type == GGML_TYPE_F16);
    GGML_ASSERT(src1->type == GGML_TYPE_F32);
    GGML_ASSERT(dst->type  == GGML_TYPE_F32);

    const int64_t ne00 = src0->ne[0];
    const int64_t ne01 = src0->ne[1];

    GGML_ASSERT(src1->ne[1] == 1);

    const int cc = ggml_cuda_info().devices[ggml_cuda_get_device()].cc;
    const enum ggml_prec prec = fast_fp16_available(cc) ? ggml_prec(dst->op_params[0]) : GGML_PREC_F32;

    const half  * src0_d = (const half  *) src0->data;
    const float * src1_d = (const float *) src1->data;
    float       *  dst_d = (float       *)  dst->data;

    const int64_t ne02 = src0->ne[2];
    const int64_t ne12 = src1->ne[2];
    GGML_ASSERT(dst->ne[2] == ne12);

    GGML_ASSERT(src0->ne[3] == 1);
    GGML_ASSERT(src1->ne[3] == 1);
    GGML_ASSERT( dst->ne[3] == 1);

    const int64_t stride_row         = src0->nb[1] / ggml_type_size(src0->type);
    const int64_t channel_stride_x   = src0->nb[2] / ggml_type_size(src0->type);
    const int64_t channel_stride_y   = src1->nb[2] / ggml_type_size(src1->type);
    const int64_t channel_stride_dst =  dst->nb[2] / ggml_type_size( dst->type);

    mul_mat_vec_cuda(src0_d, src1_d, dst_d, ne00, ne01, stride_row, ne02, ne12, channel_stride_x, channel_stride_y, channel_stride_dst, prec, ctx.stream());
}

void ggml_cuda_op_mul_mat_vec(
    ggml_backend_cuda_context & ctx,
    const ggml_tensor * src0, const ggml_tensor * src1, ggml_tensor * dst, const char * src0_dd_i, const float * src1_ddf_i,
    const char * src1_ddq_i, float * dst_dd_i, const int64_t row_low, const int64_t row_high, const int64_t src1_ncols,
    const int64_t src1_padded_row_size, cudaStream_t stream) {

    GGML_ASSERT(src0->type == GGML_TYPE_F16);
    GGML_ASSERT(src1->type == GGML_TYPE_F32);
    GGML_ASSERT(dst->type  == GGML_TYPE_F32);

    const int64_t ne00 = src0->ne[0];
    const int64_t row_diff = row_high - row_low;

    GGML_ASSERT(src1_ncols == 1);

    const int cc = ggml_cuda_info().devices[ggml_cuda_get_device()].cc;
    const enum ggml_prec prec = fast_fp16_available(cc) ? ggml_prec(dst->op_params[0]) : GGML_PREC_F32;


    // ggml_cuda_op provides single, contiguous matrices
    const int64_t stride_row         = ne00;
    const int64_t nchannels_x        = 1;
    const int64_t nchannels_y        = 1;
    const int64_t channel_stride_x   = 0;
    const int64_t channel_stride_y   = 0;
    const int64_t channel_stride_dst = 0;

    mul_mat_vec_cuda((const half *) src0_dd_i, src1_ddf_i, dst_dd_i, ne00, row_diff, stride_row,
        nchannels_x, nchannels_y, channel_stride_x, channel_stride_y, channel_stride_dst, prec, stream);

    GGML_UNUSED(ctx);
    GGML_UNUSED(src1);
    GGML_UNUSED(dst);
    GGML_UNUSED(src1_ddq_i);
    GGML_UNUSED(src1_ncols);
    GGML_UNUSED(src1_padded_row_size);
}
