swap_stub.c

来自「基于Blas CLapck的.用过的人知道是干啥的」· C语言 代码 · 共 47 行

#include "atlas_misc.h"
void ATL_USWAP(const int N, TYPE *X, const int incX, TYPE *Y, const int incY);

void ATL_SWAP(const int N, TYPE *X, const int incX,
              TYPE *Y, const int incY)
{
   int incx=incX, incy=incY;

   if (N > 0)
   {
/*
 *    Manipulate incX and inxY such that:
 *    -  Both are positive
 *    -  else if incX or incY has abs()=1, make it positive
 *    -  if both abs(inc) are 1, or if neither, make incY positive
 */
      if (incX > 0 && incY > 0) goto L1;
      else if (incY < 0)
      {
         if (incX < 0) /* make both positive */
         {
            incx = -incX;
            incy = -incY;
            X += ((N-1)SHIFT)*incX;
            Y += ((N-1)SHIFT)*incY;
         }
         else if (incX != 1 || incY == -1)
         {
            incy = -incY;
            Y += ((N-1)SHIFT)*incY;
            incx = -incX;
            X += ((N-1)SHIFT)*incX;
         }
      }
      else if (incX == -1 && incY != 1)
      {
         incx = 1;
         X -= ((N-1)SHIFT);
         incy = -incY;
         Y += ((N-1)SHIFT)*incY;
      }
      else if (!incX || !incY) return;
L1:
      ATL_USWAP(N, X, incx, Y, incy);
   }
}