OpenBLAS/kernel/zarch/zamax.c

/***************************************************************************
Copyright (c) 2013-2017, The OpenBLAS Project
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#include "common.h"
#include <math.h>

#if defined(DOUBLE)
#define ABS fabs
#else
#define ABS fabsf
#endif

#define CABS1(x,i) (ABS(x[i]) + ABS(x[i + 1]))

static FLOAT zamax_kernel_16(BLASLONG n, FLOAT *x)
{
    FLOAT amax;

    __asm__ volatile (
        "vleg   %%v0,0(%2),0              \n\t"
        "vleg   %%v16,8(%2),0             \n\t"
        "vleg   %%v0,16(%2),1             \n\t"
        "vleg   %%v16,24(%2),1            \n\t"
        "vflpdb %%v0,%%v0                 \n\t"
        "vflpdb %%v16,%%v16               \n\t"
        "vfadb  %%v0,%%v0,%%v16           \n\t"
        "srlg  %%r0,%1,4                  \n\t"
        "xgr %%r1,%%r1                    \n\t"
        "0:                               \n\t"
        "pfd 1, 1024(%%r1,%2)             \n\t"

        "vleg  %%v16,0(%%r1,%2),0         \n\t"
        "vleg  %%v17,8(%%r1,%2),0         \n\t"
        "vleg  %%v16,16(%%r1,%2),1        \n\t"
        "vleg  %%v17,24(%%r1,%2),1        \n\t"
        "vleg  %%v18,32(%%r1,%2),0        \n\t"
        "vleg  %%v19,40(%%r1,%2),0        \n\t"
        "vleg  %%v18,48(%%r1,%2),1        \n\t"
        "vleg  %%v19,56(%%r1,%2),1        \n\t"
        "vleg  %%v20,64(%%r1,%2),0        \n\t"
        "vleg  %%v21,72(%%r1,%2),0        \n\t"
        "vleg  %%v20,80(%%r1,%2),1        \n\t"
        "vleg  %%v21,88(%%r1,%2),1        \n\t"
        "vleg  %%v22,96(%%r1,%2),0        \n\t"
        "vleg  %%v23,104(%%r1,%2),0       \n\t"
        "vleg  %%v22,112(%%r1,%2),1       \n\t"
        "vleg  %%v23,120(%%r1,%2),1       \n\t"
        "vflpdb  %%v16, %%v16             \n\t"
        "vflpdb  %%v17, %%v17             \n\t"
        "vflpdb  %%v18, %%v18             \n\t"
        "vflpdb  %%v19, %%v19             \n\t"
        "vflpdb  %%v20, %%v20             \n\t"
        "vflpdb  %%v21, %%v21             \n\t"
        "vflpdb  %%v22, %%v22             \n\t"
        "vflpdb  %%v23, %%v23             \n\t"
        "vfadb %%v16,%%v16,%%v17          \n\t"
        "vfadb %%v17,%%v18,%%v19          \n\t"
        "vfadb %%v18,%%v20,%%v21          \n\t"
        "vfadb %%v19,%%v22,%%v23          \n\t"
        
        "vfchdb  %%v24,%%v16,%%v17        \n\t"
        "vfchdb  %%v25,%%v18,%%v19        \n\t"
        "vsel    %%v24,%%v16,%%v17,%%v24  \n\t"
        "vsel    %%v25,%%v18,%%v19,%%v25  \n\t"

        "vfchdb  %%v26,%%v24,%%v25        \n\t"
        "vsel    %%v26,%%v24,%%v25,%%v26  \n\t"

        "vfchdb  %%v27,%%v26,%%v0         \n\t"
        "vsel    %%v0,%%v26,%%v0,%%v27    \n\t"

        "vleg  %%v16,128(%%r1,%2),0       \n\t"
        "vleg  %%v17,136(%%r1,%2),0       \n\t"
        "vleg  %%v16,144(%%r1,%2),1       \n\t"
        "vleg  %%v17,152(%%r1,%2),1       \n\t"
        "vleg  %%v18,160(%%r1,%2),0       \n\t"
        "vleg  %%v19,168(%%r1,%2),0       \n\t"
        "vleg  %%v18,176(%%r1,%2),1       \n\t"
        "vleg  %%v19,184(%%r1,%2),1       \n\t"
        "vleg  %%v20,192(%%r1,%2),0       \n\t"
        "vleg  %%v21,200(%%r1,%2),0       \n\t"
        "vleg  %%v20,208(%%r1,%2),1       \n\t"
        "vleg  %%v21,216(%%r1,%2),1       \n\t"
        "vleg  %%v22,224(%%r1,%2),0       \n\t"
        "vleg  %%v23,232(%%r1,%2),0       \n\t"
        "vleg  %%v22,240(%%r1,%2),1       \n\t"
        "vleg  %%v23,248(%%r1,%2),1       \n\t"
        "vflpdb  %%v16, %%v16             \n\t"
        "vflpdb  %%v17, %%v17             \n\t"
        "vflpdb  %%v18, %%v18             \n\t"
        "vflpdb  %%v19, %%v19             \n\t"
        "vflpdb  %%v20, %%v20             \n\t"
        "vflpdb  %%v21, %%v21             \n\t"
        "vflpdb  %%v22, %%v22             \n\t"
        "vflpdb  %%v23, %%v23             \n\t"
        "vfadb %%v16,%%v16,%%v17          \n\t"
        "vfadb %%v17,%%v18,%%v19          \n\t"
        "vfadb %%v18,%%v20,%%v21          \n\t"
        "vfadb %%v19,%%v22,%%v23          \n\t"
        
        "vfchdb  %%v24,%%v16,%%v17        \n\t"
        "vfchdb  %%v25,%%v18,%%v19        \n\t"
        "vsel    %%v24,%%v16,%%v17,%%v24  \n\t"
        "vsel    %%v25,%%v18,%%v19,%%v25  \n\t"

        "vfchdb  %%v26,%%v24,%%v25        \n\t"
        "vsel    %%v26,%%v24,%%v25,%%v26  \n\t"

        "vfchdb  %%v27,%%v26,%%v0         \n\t"
        "vsel    %%v0,%%v26,%%v0,%%v27    \n\t"

        "agfi    %%r1, 256                \n\t"
        "brctg   %%r0, 0b                 \n\t"

        "vrepg  %%v16,%%v0,1              \n\t"
        "wfchdb %%v17,%%v16,%%v0          \n\t"
        "vsel   %%v0,%%v16,%%v0,%%v17     \n\t"
        "ldr    %0,%%f0                       "
        :"=f"(amax)
        :"r"(n),"ZR"((const FLOAT (*)[n])x)
        :"memory","cc","r0","r1","v0","v16","v17","v18","v19","v20","v21","v22","v23","v24","v25","v26","v27"
    );

    return amax;
}
 
FLOAT CNAME(BLASLONG n, FLOAT *x, BLASLONG inc_x) {
    BLASLONG i = 0;
    BLASLONG ix = 0;
    FLOAT maxf = 0.0;
    BLASLONG inc_x2;

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

    if (inc_x == 1) {

        BLASLONG n1 = n & -16;
        if (n1 > 0) {

            maxf = zamax_kernel_16(n1, x);

            i = n1;
        }
        else
        {
            maxf=CABS1(x,0);
            ix += 2;
            i++;
        }

        while (i < n) {
            if (CABS1(x,ix) > maxf) {
                maxf = CABS1(x,ix);
            }
            ix += 2;
            i++;
        }
        return (maxf);

    } else {
        
        maxf=CABS1(x,0);
        inc_x2 = 2 * inc_x;
        ix += inc_x2;
        i++;

        BLASLONG n1 = (n - 1) & -4;
        while (i < n1) {

            if (CABS1(x,ix) > maxf) {
                maxf = CABS1(x,ix);
            }
            if (CABS1(x,ix+inc_x2) > maxf) {
                maxf = CABS1(x,ix+inc_x2);
            }
            if (CABS1(x,ix+inc_x2*2) > maxf) {
                maxf = CABS1(x,ix+inc_x2*2);
            }
            if (CABS1(x,ix+inc_x2*3) > maxf) {
                maxf = CABS1(x,ix+inc_x2*3);
            }

            ix += inc_x2 * 4;

            i += 4;

        }


        while (i < n) {
            if (CABS1(x,ix) > maxf) {
                maxf = CABS1(x,ix);
            }
            ix += inc_x2;
            i++;
        }
        return (maxf);
    }
}