OSchip
/
OpenBLAS

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#include "common.h"
#include <math.h>
#include <altivec.h>
#if defined(DOUBLE)
    #define ABS fabs
#else
    #define ABS fabsf
#endif
#define CABS1(x,i)    ABS(x[i])+ABS(x[i+1])


/**
 * Find  minimum index 
 * Warning: requirements n>0  and n % 32 == 0
 * @param n     
 * @param x     pointer to the vector
 * @param minf  (out) minimum absolute value .( only for output )
 * @return  index 
 */
static BLASLONG   ciamin_kernel_32(BLASLONG n, FLOAT *x, FLOAT *minf) { 

    BLASLONG index;
    BLASLONG i=0;
    register __vector unsigned int static_index0 = {0,1,2,3};
    register __vector unsigned int temp0 = {4,4,4, 4}; //temporary vector register
    register __vector unsigned int temp1=  temp0<<1;  //{8,8,8,8}
    register __vector unsigned int static_index1=static_index0 +temp0;//{4,5,6,7};
    register __vector unsigned int static_index2=static_index0 +temp1;//{8,9,10,11};
    register __vector unsigned int static_index3=static_index1 +temp1; //{12,13,14,15};
    temp0=vec_xor(temp0,temp0);
    temp1=temp1 <<1 ; //{16,16,16,16}
    register __vector unsigned int temp_add=temp1 <<1; //{32,32,32,32}
    register __vector unsigned int quadruple_indices=temp0;//{0,0,0,0}
    float first_min=CABS1(x,0);
    register __vector float quadruple_values={first_min,first_min,first_min,first_min};

    register __vector float * v_ptrx=(__vector float *)x;
    register __vector unsigned char real_pack_mask = { 0,1,2,3,8,9,10,11,16,17,18,19, 24,25,26,27}; 
    register __vector unsigned char image_pack_mask=  {4, 5, 6, 7, 12, 13, 14, 15, 20, 21, 22, 23, 28, 29, 30, 31}; 
    for(; i<n; i+=32){
       //absolute temporary complex vectors
       register __vector float v0=vec_abs(v_ptrx[0]);
       register __vector float v1=vec_abs(v_ptrx[1]);
       register __vector float v2=vec_abs(v_ptrx[2]);
       register __vector float v3=vec_abs(v_ptrx[3]);
       register __vector float v4=vec_abs(v_ptrx[4]);
       register __vector float v5=vec_abs(v_ptrx[5]);
       register __vector float v6=vec_abs(v_ptrx[6]);       
       register __vector float v7=vec_abs(v_ptrx[7]);

       //pack complex real and imaginary parts together to sum real+image
       register __vector float t1=vec_perm(v0,v1,real_pack_mask);
       register __vector float ti=vec_perm(v0,v1,image_pack_mask);      
       v0=t1+ti; //sum quadruple real with quadruple image
       register __vector float t2=vec_perm(v2,v3,real_pack_mask);
       register __vector float ti2=vec_perm(v2,v3,image_pack_mask); 
       v1=t2+ti2;
       t1=vec_perm(v4,v5,real_pack_mask);
       ti=vec_perm(v4,v5,image_pack_mask);      
       v2=t1+ti; //sum
       t2=vec_perm(v6,v7,real_pack_mask);
       ti2=vec_perm(v6,v7,image_pack_mask); 
       v3=t2+ti2;
       // now we have 16 summed elements . lets compare them
       v_ptrx+=8;
       register __vector bool int r1=vec_cmpgt(v0,v1);
       register __vector bool int r2=vec_cmpgt(v2,v3);
       register __vector unsigned int ind2= vec_sel(static_index0,static_index1,r1);
       v0=vec_sel(v0,v1,r1); 
       register __vector unsigned int ind3= vec_sel(static_index2,static_index3,r2);
       v1=vec_sel(v2,v3,r2);
       //final cmp and select index and value for first 16 values
       r1=vec_cmpgt(v0,v1);
       register __vector unsigned int indf0 = vec_sel(ind2,ind3,r1);
       register __vector float vf0= vec_sel(v0,v1,r1); 

       //absolute temporary complex vectors
       v0=vec_abs(v_ptrx[0]);
       v1=vec_abs(v_ptrx[1]);
       v2=vec_abs(v_ptrx[2]);
       v3=vec_abs(v_ptrx[3]);
       v4=vec_abs(v_ptrx[4]);
       v5=vec_abs(v_ptrx[5]);
       v6=vec_abs(v_ptrx[6]);       
       v7=vec_abs(v_ptrx[7]);

       //pack complex real and imaginary parts together to sum real+image
       t1=vec_perm(v0,v1,real_pack_mask);
       ti=vec_perm(v0,v1,image_pack_mask);      
       v0=t1+ti; //sum quadruple real with quadruple image
       t2=vec_perm(v2,v3,real_pack_mask);
       ti2=vec_perm(v2,v3,image_pack_mask); 
       v1=t2+ti2;
       t1=vec_perm(v4,v5,real_pack_mask);
       ti=vec_perm(v4,v5,image_pack_mask);      
       v2=t1+ti; //sum
       t2=vec_perm(v6,v7,real_pack_mask);
       ti2=vec_perm(v6,v7,image_pack_mask); 
       v3=t2+ti2;
       // now we have 16 summed elements {from 16 to 31} . lets compare them
       v_ptrx+=8;
       r1=vec_cmpgt(v0,v1);
       r2=vec_cmpgt(v2,v3);
       ind2= vec_sel(static_index0,static_index1,r1);
       v0=vec_sel(v0,v1,r1); 
       ind3= vec_sel(static_index2,static_index3,r2);
       v1=vec_sel(v2,v3,r2);
       //final cmp and select index and value for the second 16 values
       r1=vec_cmpgt(v0,v1);
       register __vector unsigned int indv0 = vec_sel(ind2,ind3,r1);
       register __vector float vv0= vec_sel(v0,v1,r1); 
       indv0+=temp1; //make index from 16->31

       //find final quadruple from 32 elements
       r2=vec_cmpgt(vf0,vv0);
       ind2 = vec_sel( indf0,indv0,r2);
       vv0= vec_sel(vf0,vv0,r2);       
       //get asbolute index
       ind2+=temp0;
       //compare with old quadruple and update 
       r1=vec_cmpgt(quadruple_values,vv0);
       quadruple_indices = vec_sel( quadruple_indices,ind2,r1);
       quadruple_values= vec_sel(quadruple_values,vv0,r1);      

       temp0+=temp_add;     
    }

 //now we have to chose from 4 values and 4 different indices
    // we will compare pairwise if pairs are exactly the same we will choose minimum between index
    // otherwise we will assign index of the minimum value
    float a1,a2,a3,a4;
    unsigned int i1,i2,i3,i4;
    a1=vec_extract(quadruple_values,0);
    a2=vec_extract(quadruple_values,1);
    a3=vec_extract(quadruple_values,2);
    a4=vec_extract(quadruple_values,3);
    i1=vec_extract(quadruple_indices,0);
    i2=vec_extract(quadruple_indices,1);
    i3=vec_extract(quadruple_indices,2);
    i4=vec_extract(quadruple_indices,3);
    if(a1==a2){
       index=i1>i2?i2:i1;
    }else if(a2<a1){
      index=i2;
      a1=a2;
    }else{
       index= i1;
    }

    if(a4==a3){
      i1=i3>i4?i4:i3;
    }else if(a4<a3){
      i1=i4;
      a3=a4;
    }else{
       i1= i3;
    }

    if(a1==a3){
      index=i1>index?index:i1;
       *minf=a1; 
    }else if(a3<a1){
       index=i1;
       *minf=a3;
    }else{ 
        *minf=a1;
    }
    return index;

}
 
  
BLASLONG CNAME(BLASLONG n, FLOAT *x, BLASLONG inc_x)
{
    BLASLONG i=0;
    BLASLONG ix=0;
    FLOAT minf;
    BLASLONG min=0;
    BLASLONG inc_x2;

    if (n <= 0 || inc_x <= 0) return(min);
    

    if (inc_x == 1) {
        minf = CABS1(x,0); //index will not be incremented
        BLASLONG n1 = n & -32;
        if (n1 > 0) {

            min = ciamin_kernel_32(n1, x, &minf);
            i = n1;
            ix = n1 << 1;
        }
      

        while(i < n)
        {
            if( CABS1(x,ix) < minf )
            {
                min = i;
                minf = CABS1(x,ix);
            }
            ix += 2;
            i++;
        }
        return (min + 1);

    } else {
 
        inc_x2 = 2 * inc_x;

        minf = CABS1(x,0);
        ix += inc_x2;
        i++;

        while(i < n)
        {
            if( CABS1(x,ix) < minf )
            {
                min = i;
                minf = CABS1(x,ix);
            }
            ix += inc_x2;
            i++;
        }
        return (min + 1);
    }
 
}