OpenBLAS/kernel/x86_64/sgemv_n.c

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#include "common.h"


#define NBMAX 4096

#ifndef HAVE_KERNEL_16x4

static void sgemv_kernel_16x4(BLASLONG n, FLOAT **ap, FLOAT *x, FLOAT *y)
{
	BLASLONG i;
	FLOAT *a0,*a1,*a2,*a3;
	a0 = ap[0];
	a1 = ap[1];
	a2 = ap[2];
	a3 = ap[3];

	for ( i=0; i< n; i+=4 )
	{
		y[i] += a0[i]*x[0] + a1[i]*x[1] + a2[i]*x[2] + a3[i]*x[3];		
		y[i+1] += a0[i+1]*x[0] + a1[i+1]*x[1] + a2[i+1]*x[2] + a3[i+1]*x[3];		
		y[i+2] += a0[i+2]*x[0] + a1[i+2]*x[1] + a2[i+2]*x[2] + a3[i+2]*x[3];		
		y[i+3] += a0[i+3]*x[0] + a1[i+3]*x[1] + a2[i+3]*x[2] + a3[i+3]*x[3];		
	}
}
	
#endif

static void sgemv_kernel_16x1(BLASLONG n, FLOAT *ap, FLOAT *x, FLOAT *y)
{
	BLASLONG i;
	FLOAT *a0;
	a0 = ap;

	for ( i=0; i< n; i+=4 )
	{
		y[i] += a0[i]*x[0];		
		y[i+1] += a0[i+1]*x[0];		
		y[i+2] += a0[i+2]*x[0];		
		y[i+3] += a0[i+3]*x[0];		
	}
}
	

static void zero_y(BLASLONG n, FLOAT *dest)
{
	BLASLONG i;
	for ( i=0; i<n; i++ )
	{
		*dest = 0.0;
		dest++;
	}
}



static void add_y(BLASLONG n, FLOAT *src, FLOAT *dest, BLASLONG inc_dest)
{
	BLASLONG i;
	if ( inc_dest == 1 )
	{
		for ( i=0; i<n; i+=4 )
		{
			dest[i] += src[i];
			dest[i+1] += src[i+1];
			dest[i+2] += src[i+2];
			dest[i+3] += src[i+3];
		}

	}
	else
	{
		for ( i=0; i<n; i++ )
		{
			*dest += *src;
			src++;
			dest += inc_dest;
		}
	}
}

int CNAME(BLASLONG m, BLASLONG n, BLASLONG dummy1, FLOAT alpha, FLOAT *a, BLASLONG lda, FLOAT *x, BLASLONG inc_x, FLOAT *y, BLASLONG inc_y, FLOAT *buffer)
{
	BLASLONG i;
	BLASLONG j;
	FLOAT *a_ptr;
	FLOAT *x_ptr;
	FLOAT *y_ptr;
	FLOAT *ap[4];
	BLASLONG n1;
	BLASLONG m1;
	BLASLONG m2;
	BLASLONG n2;
	FLOAT xbuffer[4],*ybuffer;

        if ( m < 1 ) return(0);
        if ( n < 1 ) return(0);

	ybuffer = buffer;
	
	n1 = n / 4 ;
	n2 = n % 4 ;
	
	m1 = m - ( m % 16 );
	m2 = (m % NBMAX) - (m % 16) ;
	
	y_ptr = y;

	BLASLONG NB = NBMAX;

	while ( NB == NBMAX )
	{
		
		m1 -= NB;
		if ( m1 < 0)
		{
			if ( m2 == 0 ) break;	
			NB = m2;
		}
		
		a_ptr = a;
		x_ptr = x;
		zero_y(NB,ybuffer);
		for( i = 0; i < n1 ; i++)
		{
			xbuffer[0] = alpha * x_ptr[0];
			x_ptr += inc_x;	
			xbuffer[1] = alpha * x_ptr[0];
			x_ptr += inc_x;	
			xbuffer[2] = alpha * x_ptr[0];
			x_ptr += inc_x;	
			xbuffer[3] = alpha * x_ptr[0];
			x_ptr += inc_x;	
			ap[0] = a_ptr;
			ap[1] = a_ptr + lda;
			ap[2] = ap[1] + lda;
			ap[3] = ap[2] + lda;
			sgemv_kernel_16x4(NB,ap,xbuffer,ybuffer);
			a_ptr += 4 * lda;
		}

		for( i = 0; i < n2 ; i++)
		{
			xbuffer[0] = alpha * x_ptr[0];
			x_ptr += inc_x;	
			sgemv_kernel_16x1(NB,a_ptr,xbuffer,ybuffer);
			a_ptr += 1 * lda;

		}
		add_y(NB,ybuffer,y_ptr,inc_y);
		a     += NB;
		y_ptr += NB * inc_y;
	}
	j=0;
	while ( j < (m % 16))
	{
		a_ptr = a;
		x_ptr = x;
		FLOAT temp = 0.0;
		for( i = 0; i < n; i++ )
		{
			temp += a_ptr[0] * x_ptr[0];
			a_ptr += lda;
			x_ptr += inc_x;
		}
		y_ptr[0] += alpha * temp;
		y_ptr += inc_y;
		a++;
		j++;
	}
	return(0);
}