OpenBLAS/interface/swap.c

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#include <stdio.h>
#include "common.h"
#ifdef FUNCTION_PROFILE
#include "functable.h"
#endif

#if defined(THUNDERX2T99) || defined(VULCAN)
// Multithreaded swap gives performance benefits in ThunderX2T99
#else
// Disable multi-threading as it does not show any performance
// benefits. Keep the multi-threading code for the record.
#undef SMP
#endif

#ifndef CBLAS

void NAME(blasint *N, FLOAT *x, blasint *INCX, FLOAT *y, blasint *INCY){

  blasint n    = *N;
  blasint incx = *INCX;
  blasint incy = *INCY;

#else

void CNAME(blasint n, FLOAT *x, blasint incx, FLOAT *y, blasint incy){

#endif

#ifdef SMP
  int mode, nthreads;
  FLOAT dummyalpha[2] = {ZERO, ZERO};
#endif

#ifndef CBLAS
  PRINT_DEBUG_NAME;
#else
  PRINT_DEBUG_CNAME;
#endif

  if (n <= 0) return;

  IDEBUG_START;

  FUNCTION_PROFILE_START();

  if (incx < 0) x -= (n - 1) * incx;
  if (incy < 0) y -= (n - 1) * incy;

#ifdef SMP
  //disable multi-thread when incx==0 or incy==0
  //In that case, the threads would be dependent.
  if (incx == 0 || incy == 0 || n < 2097152 * GEMM_MULTITHREAD_THRESHOLD / sizeof(FLOAT))
    nthreads = 1;
  else
    nthreads = num_cpu_avail(1);

  if (nthreads == 1) {
#endif

    SWAP_K(n, 0, 0, ZERO, x, incx, y, incy, NULL, 0);

#ifdef SMP
  } else {

#ifdef XDOUBLE
    mode  =  BLAS_XDOUBLE | BLAS_REAL;
#elif defined(DOUBLE)
    mode  =  BLAS_DOUBLE  | BLAS_REAL;
#else
    mode  =  BLAS_SINGLE  | BLAS_REAL;
#endif

    blas_level1_thread(mode, n, 0, 0, dummyalpha,
		       x, incx, y, incy, NULL, 0, (void *)SWAP_K, nthreads);
  }

#endif

  FUNCTION_PROFILE_END(1, 2 * n, 0);

  IDEBUG_END;

  return;

}