semaphore.h

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#pragma once

#include "cutlass/cutlass.h"

#include "cutlass/aligned_buffer.h"
#include "cutlass/array.h"

#include "cutlass/numeric_types.h"
#include "cutlass/matrix_shape.h"

#include "cutlass/gemm/gemm.h"


namespace cutlass {


class Semaphore { 
public:

  int *lock;
  bool wait_thread;
  int state;

public:

  CUTLASS_HOST_DEVICE
  Semaphore(int *lock_, int thread_id): 
    lock(lock_), 
    wait_thread(thread_id < 0 || thread_id == 0),
    state(-1) {

  }

  CUTLASS_DEVICE
  void fetch() {

    asm volatile ("ld.global.cg.s32 %0, [%1];\n" : "=r"(state) : "l"(lock));
  }

  CUTLASS_DEVICE
  int get_state() const {
    return state;
  }

  CUTLASS_DEVICE
  void wait(int status = 0) {

    if (wait_thread) {
      while (state != status) {

        fetch();

        __syncwarp(0x01);

      };
    }

    __syncthreads();
  }

  CUTLASS_DEVICE
  void release(int status = 0) {
    __syncthreads();

    if (wait_thread) {

      asm volatile ("st.global.cg.s32 [%0], %1;\n" : : "l"(lock), "r"(status));
    }
  }
};


} // namespace cutlass