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#include <iostream>

#include "cutlass/cutlass.h"
#include "cutlass/gemm/device/gemm.h"

#include "cutlass/util/command_line.h"
#include "cutlass/util/host_tensor.h"
#include "cutlass/util/reference/device/gemm.h"
#include "cutlass/util/reference/host/tensor_compare.h"
#include "cutlass/util/reference/host/tensor_copy.h"
#include "cutlass/util/reference/host/tensor_fill.h"
#include "cutlass/util/tensor_view_io.h"

#include "helper.h"

/////////////////////////////////////////////////////////////////////////////////////////////////

/// Result structure
struct Result {

  double runtime_ms;
  double gflops;
  cutlass::Status status;
  cudaError_t error;
  bool passed;

  //
  // Methods
  //

  Result(
    double runtime_ms = 0,
    double gflops = 0,
    cutlass::Status status = cutlass::Status::kSuccess,
    cudaError_t error = cudaSuccess
  ):
    runtime_ms(runtime_ms), gflops(gflops), status(status), error(error), passed(true) { }
};

///////////////////////////////////////////////////////////////////////////////////////////////////

// Command line options parsing
struct Options {

  bool help;

  cutlass::gemm::GemmCoord problem_size;
  int batch_count;
  cutlass::Quaternion<float> alpha;
  cutlass::Quaternion<float> beta;

  bool reference_check;
  int iterations;
  
  Options():
    help(false),
    problem_size({1024, 1024, 1024}),
    batch_count(1),
    reference_check(true),
    iterations(20),
    alpha(1),
    beta() { }

  bool valid() {
    return true;
  }

  // Parses the command line
  void parse(int argc, char const **args) {
    cutlass::CommandLine cmd(argc, args);

    if (cmd.check_cmd_line_flag("help")) {
      help = true;
    }

    cmd.get_cmd_line_argument("m", problem_size.m());
    cmd.get_cmd_line_argument("n", problem_size.n());
    cmd.get_cmd_line_argument("k", problem_size.k());
    cmd.get_cmd_line_argument("batch", batch_count);

    cmd.get_cmd_line_argument("alpha",   alpha.w());
    cmd.get_cmd_line_argument("alpha_i", alpha.x());
    cmd.get_cmd_line_argument("alpha_j", alpha.y());
    cmd.get_cmd_line_argument("alpha_k", alpha.z());

    cmd.get_cmd_line_argument("beta",   beta.w());
    cmd.get_cmd_line_argument("beta_i", beta.x());
    cmd.get_cmd_line_argument("beta_j", beta.y());
    cmd.get_cmd_line_argument("beta_k", beta.z());
    
    cmd.get_cmd_line_argument("iterations", iterations);

  }

  /// Prints the usage statement.
  std::ostream & print_usage(std::ostream &out) const {

    out << "21_quaternion_gemm example\n\n"
      << "  This example uses the CUTLASS Library to execute Quaternion GEMM computations.\n\n"
      << "Options:\n\n"
      << "  --help                      If specified, displays this usage statement.\n\n"
      << "  --m=<int>                   GEMM M dimension\n"
      << "  --n=<int>                   GEMM N dimension\n"
      << "  --k=<int>                   GEMM K dimension\n"
      << "  --batch=<int>               Number of GEMM operations executed in one batch\n"
      << "  --alpha=<f32>               Epilogue scalar alpha (real part)\n"
      << "  --alpha_i=<f32>             Epilogue scalar alpha_i (imaginary part)\n"
      << "  --alpha_j=<f32>             Epilogue scalar alpha_j (imaginary part)\n"
      << "  --alpha_k=<f32>             Epilogue scalar alpha_k (imaginary part)\n"
      << "  --beta=<f32>                Epilogue scalar beta (real part)\n\n"
      << "  --beta_i=<f32>              Epilogue scalar beta_i (imaginary part)\n\n"
      << "  --beta_j=<f32>              Epilogue scalar beta_j (imaginary part)\n\n"
      << "  --beta_k=<f32>              Epilogue scalar beta_k (imaginary part)\n\n"
      << "  --iterations=<int>          Number of profiling iterations to perform.\n\n";

    out << "\n\nExamples:\n\n"
      << "$ ./examples/21_quaternion_gemm/21_quaternion_gemm  --batch=7 --m=1024 --n=512 --k=1024 \\\n"
      << "     --alpha=2 --alpha_i=-2 --beta=0.707 --beta_i=-.707\n\n";

    return out;
  }

  /// Compute performance in GFLOP/s
  double gflops(double runtime_s) const {

    // Number of real-valued multiply-adds 
    int64_t fmas = problem_size.product() * batch_count * 16;
    
    // Two flops per multiply-add
    return 2.0 * double(fmas) / double(1.0e9) / runtime_s;
  }
};

///////////////////////////////////////////////////////////////////////////////////////////////////

// The code section below describes datatype for input, output matrices and computation between
// elements in input matrices.
using precision = float;
using Element = cutlass::Quaternion<float>;
using ElementComputeEpilogue = Element;  // <- data type of epilogue operations
using ElementAccumulator = Element;      // <- data type of accumulator
using ElementInputA = Element;           // <- data type of elements in input matrix A
using ElementInputB = Element;           // <- data type of elements in input matrix B
using ElementOutput = Element;           // <- data type of elements in output matrix D

// The code section below describes matrix layout of input and output matrices. Column Major for
// Matrix A, Row Major for Matrix B and Row Major for Matrix C
using LayoutInputA = cutlass::layout::RowMajor;
using LayoutInputB = cutlass::layout::ColumnMajor;
using LayoutOutput = cutlass::layout::RowMajor;

// This code section describes whether you want to use tensor cores or regular SIMT cores on GPU SM
using MMAOp = cutlass::arch::OpClassSimt;

// This code section describes CUDA SM architecture number
using SmArch = cutlass::arch::Sm50;

// This code section describes the tile size a thread block will compute
using ShapeMMAThreadBlock =
    cutlass::gemm::GemmShape<64, 64, 4>;                   // <- threadblock tile M = 64, N = 64, K = 8
// This code section describes tile size a warp will compute
using ShapeMMAWarp = cutlass::gemm::GemmShape<32, 16, 4>;  // <- warp tile M = 32, N = 16, K = 8
// This code section describes the size of MMA op
using ShapeMMAOp = cutlass::gemm::GemmShape<1, 1, 1>;      // <- MMA Op tile M = 1, N = 1, K = 1

// This code section describes how threadblocks are scheduled on GPU
using SwizzleThreadBlock = cutlass::gemm::threadblock::GemmIdentityThreadblockSwizzle<>;  // <- Defaults

// This code section describes the epilogue part of the kernel
using EpilogueOp = cutlass::epilogue::thread::LinearCombination<
    ElementOutput,                                    // <- data type of output matrix
    128 / cutlass::sizeof_bits<ElementOutput>::value, // <- the number of elements per vectorized
                                                      // memory access. For a byte, it's 16
                                                      // elements. This becomes the vector width of
                                                      // math instructions in the epilogue too
    ElementAccumulator,                               // <- data type of accumulator
    ElementComputeEpilogue>;                          // <- data type for alpha/beta in linear combination function

// Number of pipelines you want to use
constexpr int NumStages = 2;

using Gemm = cutlass::gemm::device::Gemm<ElementInputA,
                                         LayoutInputA,
                                         ElementInputB,
                                         LayoutInputB,
                                         ElementOutput,
                                         LayoutOutput,
                                         ElementAccumulator,
                                         MMAOp,
                                         SmArch,
                                         ShapeMMAThreadBlock,
                                         ShapeMMAWarp,
                                         ShapeMMAOp,
                                         EpilogueOp,
                                         SwizzleThreadBlock,
                                         NumStages>;

int run(Options options) {

  // PASS/FAIL status
  bool passed = true;

  // Create a tuple of problem size for matrix multiplication
  cutlass::gemm::GemmCoord problem_size = options.problem_size;

  // Initialize tensors using CUTLASS helper functions
  cutlass::HostTensor<ElementInputA, LayoutInputA> tensor_a(
      problem_size.mk());  // <- Create matrix A with dimensions M x K
  cutlass::HostTensor<ElementInputB, LayoutInputB> tensor_b(
      problem_size.kn());  // <- Create matrix B with dimensions K x N
  cutlass::HostTensor<ElementOutput, LayoutOutput> tensor_c(
      problem_size.mn());  // <- Create matrix C with dimensions M x N
  cutlass::HostTensor<ElementOutput, LayoutOutput> tensor_d(
      problem_size.mn());  // <- Create matrix D with dimensions M x N used to store output from
                           // CUTLASS kernel
  cutlass::HostTensor<ElementOutput, LayoutOutput> tensor_ref_d(
      problem_size.mn());  // <- Create matrix D with dimensions M x N used to store output from
                           // reference kernel

  // Fill input and output matrices on host using CUTLASS helper functions
  cutlass::reference::host::TensorFillRandomUniform(
      tensor_a.host_view(),
      1,
      4,
      -4,
      0);  // <- Fill matrix A on host with uniform-distribution random data

  cutlass::reference::host::TensorFillRandomUniform(
      tensor_b.host_view(),
      1,
      4,
      -4,
      0);  // <- Fill matrix B on host with uniform-distribution random data

  cutlass::reference::host::TensorFillRandomUniform(
      tensor_c.host_view(),
      1,
      4,
      -4,
      0);  // <- Fill matrix C on host with uniform-distribution random data

  cutlass::reference::host::TensorFill(
      tensor_d.host_view());  // <- fill matrix D on host with zeros
  cutlass::reference::host::TensorFill(
      tensor_ref_d.host_view());  // <- fill matrix D for reference on host with zeros

  // Copy data from host to GPU
  tensor_a.sync_device();
  tensor_b.sync_device();
  tensor_c.sync_device();
  tensor_d.sync_device();
  tensor_ref_d.sync_device();

  // Initialize alpha and beta for dot product computation
  ElementComputeEpilogue alpha = ElementComputeEpilogue(1);
  ElementComputeEpilogue beta = ElementComputeEpilogue(0);

  // Split K dimension into 1 partitions
  int split_k_slices = 1;

  // Create a tuple of gemm kernel arguments. This is later passed as arguments to launch
  // instantiated CUTLASS kernel
  typename Gemm::Arguments arguments{problem_size,  // <- problem size of matrix multiplication
                                     tensor_a.device_ref(),  // <- reference to matrix A on device
                                     tensor_b.device_ref(),  // <- reference to matrix B on device
                                     tensor_c.device_ref(),  // <- reference to matrix C on device
                                     tensor_d.device_ref(),  // <- reference to matrix D on device
                                     {alpha, beta},          // <- tuple of alpha and beta
                                     split_k_slices};        // <- k-dimension split factor

  // Using the arguments, query for extra workspace required for matrix multiplication computation
  size_t workspace_size = Gemm::get_workspace_size(arguments);

  // Allocate workspace memory
  cutlass::device_memory::allocation<uint8_t> workspace(workspace_size);

  // Instantiate CUTLASS kernel depending on templates
  Gemm gemm_op;

  // Check the problem size is supported or not 
  cutlass::Status status = gemm_op.can_implement(arguments);
  CUTLASS_CHECK(status);

  // Initialize CUTLASS kernel with arguments and workspace pointer
  status = gemm_op.initialize(arguments, workspace.get());
  CUTLASS_CHECK(status);
  
  // Result structure
  Result result;

  //
  // Construct events
  //

  cudaEvent_t events[2];

  for (auto & event : events) {
    result.error = cudaEventCreate(&event);
    if (result.error != cudaSuccess) {
      std::cerr << "cudaEventCreate() failed: " << cudaGetErrorString(result.error) << std::endl;
      return -1;
    }
  }

  // Record an event at the start of a series of GEMMs
  result.error = cudaEventRecord(events[0]);
  if (result.error != cudaSuccess) {
    std::cerr << "cudaEventRecord() failed: " << cudaGetErrorString(result.error) << std::endl;
    return -1;
  }

  //
  // Run profiling loop
  //

  for (int iter = 0; iter < options.iterations; ++iter) {

    // Launch initialized CUTLASS kernel
    status = gemm_op();
    CUTLASS_CHECK(status);

  }

  //
  // Stop profiling loop
  //

  // Record an event when the GEMMs are complete
  result.error = cudaEventRecord(events[1]);
  if (result.error != cudaSuccess) {
    std::cerr << "cudaEventRecord() failed: " << cudaGetErrorString(result.error) << std::endl;
    return -1;
  }

  // Wait for work on the device to complete.
  result.error = cudaEventSynchronize(events[1]);
  if (result.error != cudaSuccess) {
    std::cerr << "cudaEventSynchronize() failed: " << cudaGetErrorString(result.error) << std::endl;
    return -1;
  }

  // Measure elapsed runtime
  float runtime_ms = 0;
  result.error = cudaEventElapsedTime(&runtime_ms, events[0], events[1]);
  if (result.error != cudaSuccess) {
    std::cerr << "cudaEventElapsed() failed: " << cudaGetErrorString(result.error) << std::endl;
    return -1;
  }

  // Compute average runtime and GFLOPs.
  result.runtime_ms = double(runtime_ms) / double(options.iterations);
  result.gflops = options.gflops(result.runtime_ms / 1000.0);

  // Cleanup
  for (auto event : events) {
    (void)cudaEventDestroy(event);
  }

  if (options.reference_check) {

    // Create instantiation for device reference gemm kernel
    cutlass::reference::device::Gemm<ElementInputA,
                                     LayoutInputA,
                                     ElementInputB,
                                     LayoutInputB,
                                     ElementOutput,
                                     LayoutOutput,
                                     ElementComputeEpilogue,
                                     ElementComputeEpilogue> gemm_device;

    // Launch device reference gemm kernel
    gemm_device(problem_size,
                alpha,
                tensor_a.device_ref(),
                tensor_b.device_ref(),
                beta,
                tensor_c.device_ref(),
                tensor_ref_d.device_ref());

    // Wait for kernels to finish
    cudaDeviceSynchronize();

    // Copy output data from CUTLASS and reference kernel to host for comparison
    tensor_d.sync_host();
    tensor_ref_d.sync_host();

    // Check if output from CUTLASS kernel and reference kernel are equal or not
    passed &= cutlass::reference::host::TensorEquals(
      tensor_d.host_view(),
      tensor_ref_d.host_view());

  }

  if (passed) {
    std::cout << "Runtime: " << result.runtime_ms << " ms" << std::endl;
    std::cout << " GFLOPs: " << result.gflops << std::endl;
  }

  std::cout << (passed ? "Passed" : "Failed") << std::endl;
  return (passed ? 0  : -1);
}

int main(int argc, char const** argv) {

  Options options;
  options.parse(argc, argv);

  if (options.help) {
    options.print_usage(std::cout) << std::endl;
    return 0;
  }

  printf("%d x %d x %d Single Precision Quaternion Matrix Multiply\n", \
    options.problem_size.m(), options.problem_size.n(), options.problem_size.k());

  if (!options.valid()) {
    std::cerr << "Invalid problem." << std::endl;
    return -1;
  }

  return run(options);
}