OpenBLAS/kernel/zarch/camax.c

/***************************************************************************
Copyright (c) 2013-2019, The OpenBLAS Project
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#include "common.h"
#include <math.h>

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

static FLOAT camax_kernel_32(BLASLONG n, FLOAT *x) {
  FLOAT amax;

  __asm__("vlef   %%v0,0(%[x]),0\n\t"
    "vlef   %%v16,4(%[x]),0\n\t"
    "vlef   %%v0,8(%[x]),1\n\t"
    "vlef   %%v16,12(%[x]),1\n\t"
    "vlef   %%v0,16(%[x]),2\n\t"
    "vlef   %%v16,20(%[x]),2\n\t"
    "vlef   %%v0,24(%[x]),3\n\t"
    "vlef   %%v16,28(%[x]),3\n\t"
    "vflpsb %%v0,%%v0\n\t"
    "vflpsb %%v16,%%v16\n\t"
    "vfasb  %%v0,%%v0,%%v16\n\t"
    "vleib  %%v1,0,0\n\t"
    "vleib  %%v1,1,1\n\t"
    "vleib  %%v1,2,2\n\t"
    "vleib  %%v1,3,3\n\t"
    "vleib  %%v1,8,4\n\t"
    "vleib  %%v1,9,5\n\t"
    "vleib  %%v1,10,6\n\t"
    "vleib  %%v1,11,7\n\t"
    "vleib  %%v1,16,8\n\t"
    "vleib  %%v1,17,9\n\t"
    "vleib  %%v1,18,10\n\t"
    "vleib  %%v1,19,11\n\t"
    "vleib  %%v1,24,12\n\t"
    "vleib  %%v1,25,13\n\t"
    "vleib  %%v1,26,14\n\t"
    "vleib  %%v1,27,15\n\t"
    "srlg  %[n],%[n],5\n\t"
    "xgr %%r1,%%r1\n\t"
    "0:\n\t"
    "pfd 1, 1024(%%r1,%[x])\n\t"
    "vl    %%v16,0(%%r1,%[x])\n\t"
    "vl    %%v2,16(%%r1,%[x])\n\t"
    "vpkg  %%v17,%%v16,%%v2\n\t"
    "vperm %%v16,%%v16,%%v2,%%v1\n\t"
    "vl    %%v18,32(%%r1,%[x])\n\t"
    "vl    %%v2,48(%%r1,%[x])\n\t"
    "vpkg  %%v19,%%v18,%%v2\n\t"
    "vperm %%v18,%%v18,%%v2,%%v1\n\t"
    "vl    %%v20,64(%%r1,%[x])\n\t"
    "vl    %%v2,80(%%r1,%[x])\n\t"
    "vpkg  %%v21,%%v20,%%v2\n\t"
    "vperm %%v20,%%v20,%%v2,%%v1\n\t"
    "vl    %%v22,96(%%r1,%[x])\n\t"
    "vl    %%v2,112(%%r1,%[x])\n\t"
    "vpkg  %%v23,%%v22,%%v2\n\t"
    "vperm %%v22,%%v22,%%v2,%%v1\n\t"
    "vl    %%v24,128(%%r1,%[x])\n\t"
    "vl    %%v2,144(%%r1,%[x])\n\t"
    "vpkg  %%v25,%%v24,%%v2\n\t"
    "vperm %%v24,%%v24,%%v2,%%v1\n\t"
    "vl    %%v26,160(%%r1,%[x])\n\t"
    "vl    %%v2,176(%%r1,%[x])\n\t"
    "vpkg  %%v27,%%v26,%%v2\n\t"
    "vperm %%v26,%%v26,%%v2,%%v1\n\t"
    "vl    %%v28,192(%%r1,%[x])\n\t"
    "vl    %%v2,208(%%r1,%[x])\n\t"
    "vpkg  %%v29,%%v28,%%v2\n\t"
    "vperm %%v28,%%v28,%%v2,%%v1\n\t"
    "vl    %%v30,224(%%r1,%[x])\n\t"
    "vl    %%v2,240(%%r1,%[x])\n\t"
    "vpkg  %%v31,%%v30,%%v2\n\t"
    "vperm %%v30,%%v30,%%v2,%%v1\n\t"
    "vflpsb  %%v16,%%v16\n\t"
    "vflpsb  %%v17,%%v17\n\t"
    "vflpsb  %%v18,%%v18\n\t"
    "vflpsb  %%v19,%%v19\n\t"
    "vflpsb  %%v20,%%v20\n\t"
    "vflpsb  %%v21,%%v21\n\t"
    "vflpsb  %%v22,%%v22\n\t"
    "vflpsb  %%v23,%%v23\n\t"
    "vflpsb  %%v24,%%v24\n\t"
    "vflpsb  %%v25,%%v25\n\t"
    "vflpsb  %%v26,%%v26\n\t"
    "vflpsb  %%v27,%%v27\n\t"
    "vflpsb  %%v28,%%v28\n\t"
    "vflpsb  %%v29,%%v29\n\t"
    "vflpsb  %%v30,%%v30\n\t"
    "vflpsb  %%v31,%%v31\n\t"
    "vfasb %%v16,%%v16,%%v17\n\t"
    "vfasb %%v18,%%v18,%%v19\n\t"
    "vfasb %%v20,%%v20,%%v21\n\t"
    "vfasb %%v22,%%v22,%%v23\n\t"
    "vfasb %%v24,%%v24,%%v25\n\t"
    "vfasb %%v26,%%v26,%%v27\n\t"
    "vfasb %%v28,%%v28,%%v29\n\t"
    "vfasb %%v30,%%v30,%%v31\n\t"
    "vfmaxsb  %%v16,%%v16,%%v24,0\n\t"
    "vfmaxsb  %%v18,%%v18,%%v26,0\n\t"
    "vfmaxsb  %%v20,%%v20,%%v28,0\n\t"
    "vfmaxsb  %%v22,%%v22,%%v30,0\n\t"
    "vfmaxsb  %%v16,%%v16,%%v20,0\n\t"
    "vfmaxsb  %%v18,%%v18,%%v22,0\n\t"
    "vfmaxsb  %%v16,%%v16,%%v18,0\n\t"
    "vfmaxsb  %%v0,%%v0,%%v16,0\n\t"
    "agfi    %%r1, 256\n\t"
    "brctg   %[n], 0b\n\t"
    "veslg   %%v16,%%v0,32\n\t"
    "vfmaxsb %%v0,%%v0,%%v16,0\n\t"
    "vrepf  %%v16,%%v0,2\n\t"
    "wfmaxsb %%v0,%%v0,%%v16,0\n\t"
    "ler    %[amax],%%f0"
    : [amax] "=f"(amax),[n] "+&r"(n)
    : "m"(*(const FLOAT (*)[n * 2]) x),[x] "a"(x)
    : "cc", "r1", "v0", "v1", "v2", "v16", "v17", "v18", "v19", "v20",
       "v21", "v22", "v23", "v24", "v25", "v26", "v27", "v28", "v29", "v30",
       "v31");

  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 & -32;
    if (n1 > 0) {

      maxf = camax_kernel_32(n1, x);
      ix = n1 * 2;
      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;

    BLASLONG n1 = n & -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);
  }
}