/***************************************************************************
Copyright (c) 2019, The OpenBLAS Project
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modification, are permitted provided that the following conditions are
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its contributors may be used to endorse or promote products
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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ARE DISCLAIMED. IN NO EVENT SHALL THE OPENBLAS PROJECT OR CONTRIBUTORS BE
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*****************************************************************************/

#include "common.h"
#include <math.h>

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

static BLASLONG izamax_kernel_16(BLASLONG n, FLOAT *x, FLOAT *amax) {
  BLASLONG iamax;

  __asm__("vleg   %%v0,0(%[x]),0\n\t"
    "vleg   %%v1,8(%[x]),0\n\t"
    "vleg   %%v0,16(%[x]),1\n\t"
    "vleg   %%v1,24(%[x]),1\n\t"
    "vflpdb %%v0,%%v0\n\t"
    "vflpdb %%v1,%%v1\n\t"
    "vfadb  %%v0,%%v0,%%v1\n\t"
    "vleig  %%v1,0,0\n\t"
    "vleig  %%v1,1,1\n\t"
    "vrepig %%v2,8\n\t"
    "vzero  %%v3\n\t"
    "vleig  %%v24,0,0\n\t"
    "vleig  %%v24,1,1\n\t"
    "vleig  %%v25,2,0\n\t"
    "vleig  %%v25,3,1\n\t"
    "vleig  %%v26,4,0\n\t"
    "vleig  %%v26,5,1\n\t"
    "vleig  %%v27,6,0\n\t"
    "vleig  %%v27,7,1\n\t"
    "srlg  %[n],%[n],4\n\t"
    "xgr %%r1,%%r1\n\t"
    "0:\n\t"
    "pfd 1, 1024(%%r1,%[x])\n\t"
    "vleg  %%v16,0(%%r1,%[x]),0\n\t"
    "vleg  %%v17,8(%%r1,%[x]),0\n\t"
    "vleg  %%v16,16(%%r1,%[x]),1\n\t"
    "vleg  %%v17,24(%%r1,%[x]),1\n\t"
    "vleg  %%v18,32(%%r1,%[x]),0\n\t"
    "vleg  %%v19,40(%%r1,%[x]),0\n\t"
    "vleg  %%v18,48(%%r1,%[x]),1\n\t"
    "vleg  %%v19,56(%%r1,%[x]),1\n\t"
    "vleg  %%v20,64(%%r1,%[x]),0\n\t"
    "vleg  %%v21,72(%%r1,%[x]),0\n\t"
    "vleg  %%v20,80(%%r1,%[x]),1\n\t"
    "vleg  %%v21,88(%%r1,%[x]),1\n\t"
    "vleg  %%v22,96(%%r1,%[x]),0\n\t"
    "vleg  %%v23,104(%%r1,%[x]),0\n\t"
    "vleg  %%v22,112(%%r1,%[x]),1\n\t"
    "vleg  %%v23,120(%%r1,%[x]),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"
    "vfchedb  %%v4,%%v16,%%v17\n\t"
    "vfchedb  %%v5,%%v18,%%v19\n\t"
    "vsel    %%v16,%%v16,%%v17,%%v4\n\t"
    "vsel    %%v4,%%v24,%%v25,%%v4\n\t"
    "vsel    %%v17,%%v18,%%v19,%%v5\n\t"
    "vsel    %%v5,%%v26,%%v27,%%v5\n\t"
    "vfchedb  %%v18,%%v16,%%v17\n\t"
    "vsel    %%v16,%%v16,%%v17,%%v18\n\t"
    "vsel    %%v4,%%v4,%%v5,%%v18\n\t"
    "vag     %%v4,%%v4,%%v3\n\t"
    "vfchedb  %%v5,%%v0,%%v16\n\t"
    "vsel    %%v0,%%v0,%%v16,%%v5\n\t"
    "vsel    %%v1,%%v1,%%v4,%%v5\n\t"
    "vag     %%v3,%%v3,%%v2\n\t"
    "vleg  %%v16,128(%%r1,%[x]),0\n\t"
    "vleg  %%v17,136(%%r1,%[x]),0\n\t"
    "vleg  %%v16,144(%%r1,%[x]),1\n\t"
    "vleg  %%v17,152(%%r1,%[x]),1\n\t"
    "vleg  %%v18,160(%%r1,%[x]),0\n\t"
    "vleg  %%v19,168(%%r1,%[x]),0\n\t"
    "vleg  %%v18,176(%%r1,%[x]),1\n\t"
    "vleg  %%v19,184(%%r1,%[x]),1\n\t"
    "vleg  %%v20,192(%%r1,%[x]),0\n\t"
    "vleg  %%v21,200(%%r1,%[x]),0\n\t"
    "vleg  %%v20,208(%%r1,%[x]),1\n\t"
    "vleg  %%v21,216(%%r1,%[x]),1\n\t"
    "vleg  %%v22,224(%%r1,%[x]),0\n\t"
    "vleg  %%v23,232(%%r1,%[x]),0\n\t"
    "vleg  %%v22,240(%%r1,%[x]),1\n\t"
    "vleg  %%v23,248(%%r1,%[x]),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"
    "vfchedb  %%v4,%%v16,%%v17\n\t"
    "vfchedb  %%v5,%%v18,%%v19\n\t"
    "vsel    %%v16,%%v16,%%v17,%%v4\n\t"
    "vsel    %%v4,%%v24,%%v25,%%v4\n\t"
    "vsel    %%v17,%%v18,%%v19,%%v5\n\t"
    "vsel    %%v5,%%v26,%%v27,%%v5\n\t"
    "vfchedb  %%v18,%%v16,%%v17\n\t"
    "vsel    %%v16,%%v16,%%v17,%%v18\n\t"
    "vsel    %%v4,%%v4,%%v5,%%v18\n\t"
    "vag     %%v4,%%v4,%%v3\n\t"
    "vfchedb  %%v5,%%v0,%%v16\n\t"
    "vsel    %%v0,%%v0,%%v16,%%v5\n\t"
    "vsel    %%v1,%%v1,%%v4,%%v5\n\t"
    "vag     %%v3,%%v3,%%v2\n\t"
    "agfi    %%r1, 256\n\t"
    "brctg   %[n], 0b\n\t"
    "vrepg  %%v2,%%v0,1\n\t"
    "vrepg  %%v3,%%v1,1\n\t"
    "wfcdb  %%v2,%%v0\n\t"
    "jne 1f\n\t"
    "vsteg  %%v0,%[amax],0\n\t"
    "vmnlg  %%v0,%%v1,%%v3\n\t"
    "vlgvg  %[iamax],%%v0,0\n\t"
    "j 2f\n\t"
    "1:\n\t"
    "wfchdb %%v4,%%v2,%%v0\n\t"
    "vsel   %%v1,%%v3,%%v1,%%v4\n\t"
    "vsel   %%v0,%%v2,%%v0,%%v4\n\t"
    "std    %%f0,%[amax]\n\t"
    "vlgvg  %[iamax],%%v1,0\n\t"
    "2:\n\t"
    "nop"
    : [iamax] "=r"(iamax),[amax] "=Q"(*amax),[n] "+&r"(n)
    : "m"(*(const struct { FLOAT x[n * 2]; } *) x),[x] "a"(x)
    : "cc", "r1", "v0", "v1", "v2", "v3", "v4", "v5", "v16", "v17", "v18",
       "v19", "v20", "v21", "v22", "v23", "v24", "v25", "v26", "v27");

  return iamax;
}

BLASLONG CNAME(BLASLONG n, FLOAT *x, BLASLONG inc_x) {
  BLASLONG i = 0;
  BLASLONG ix = 0;
  FLOAT maxf = 0;
  BLASLONG max = 0;
  BLASLONG inc_x2;

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

  if (inc_x == 1) {

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

      max = izamax_kernel_16(n1, x, &maxf);
      ix = n1 * 2;
      i = n1;
    } else {
      maxf = CABS1(x, 0);
      ix += 2;
      i++;
    }

    while (i < n) {
      if (CABS1(x, ix) > maxf) {
        max = i;
        maxf = CABS1(x, ix);
      }
      ix += 2;
      i++;
    }
    return (max + 1);

  } else {

    max = 0;
    maxf = CABS1(x, 0);
    inc_x2 = 2 * inc_x;

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

      if (CABS1(x, ix) > maxf) {
        max = i;
        maxf = CABS1(x, ix);
      }
      if (CABS1(x, ix + inc_x2) > maxf) {
        max = i + 1;
        maxf = CABS1(x, ix + inc_x2);
      }
      if (CABS1(x, ix + 2 * inc_x2) > maxf) {
        max = i + 2;
        maxf = CABS1(x, ix + 2 * inc_x2);
      }
      if (CABS1(x, ix + 3 * inc_x2) > maxf) {
        max = i + 3;
        maxf = CABS1(x, ix + 3 * inc_x2);
      }

      ix += inc_x2 * 4;

      i += 4;

    }

    while (i < n) {
      if (CABS1(x, ix) > maxf) {
        max = i;
        maxf = CABS1(x, ix);
      }
      ix += inc_x2;
      i++;
    }
    return (max + 1);
  }
}
