OpenBLAS/interface/axpy.c

/*********************************************************************/
/* Copyright 2009, 2010 The University of Texas at Austin.           */
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/*    THIS  SOFTWARE IS PROVIDED  BY THE  UNIVERSITY OF  TEXAS AT    */
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#include <stdio.h>
#include "common.h"
#ifdef FUNCTION_PROFILE
#include "functable.h"
#endif
#if  defined(Z13)
#define MULTI_THREAD_MINIMAL  200000
#else
#define MULTI_THREAD_MINIMAL  10000
#endif
#ifndef CBLAS

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

  BLASLONG n    = *N;
  BLASLONG incx = *INCX;
  BLASLONG incy = *INCY;
  FLOAT alpha = *ALPHA;

#else

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

#endif

#ifdef SMP
  int mode, nthreads;
#endif

#ifndef CBLAS
  PRINT_DEBUG_NAME;
#else
  PRINT_DEBUG_CNAME;
#endif

  if (n <= 0) return;

  if (alpha == ZERO) return;

  if (incx == 0 && incy == 0) {
    *y += n * alpha *(*x);
    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.
  //
  //Temporarily work-around the low performance issue with small input size &
  //multithreads.
  if (incx == 0 || incy == 0 || n <= MULTI_THREAD_MINIMAL)
	  nthreads = 1;
  else
	  nthreads = num_cpu_avail(1);

  if (nthreads == 1) {
#endif

  AXPYU_K(n, 0, 0, alpha, 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, &alpha,
		       x, incx, y, incy, NULL, 0,  (int (*)(void))AXPYU_K, nthreads);

  }
#endif

  FUNCTION_PROFILE_END(1, 2 * n, 2 * n);

  IDEBUG_END;

  return;

}