/***************************************************************************
Copyright (c) 2022, The OpenBLAS Project
All rights reserved.
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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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*****************************************************************************/

#include "common.h"

#if defined(DOUBLE)
#define VSETVL(n) vsetvl_e64m4(n)
#define VSETVL_MAX vsetvlmax_e64m4()
#define FLOAT_V_T vfloat64m4_t
#define FLOAT_V_T_M1 vfloat64m1_t
#define VLEV_FLOAT vle64_v_f64m4
#define VLSEV_FLOAT vlse64_v_f64m4
#define VLSEG_FLOAT vlseg2e64_v_f64m4
#define VLSSEG_FLOAT vlsseg2e64_v_f64m4
#define VFREDMAXVS_FLOAT vfredmax_vs_f64m4_f64m1
#define MASK_T vbool16_t
#define VMFLTVF_FLOAT vmflt_vf_f64m4_b16
#define VMFLTVV_FLOAT vmflt_vv_f64m4_b16
#define VMFGEVF_FLOAT vmfge_vf_f64m4_b16
#define VFMVVF_FLOAT vfmv_v_f_f64m4
#define VFMVVF_FLOAT_M1 vfmv_v_f_f64m1
#define VFABSV_FLOAT vfabs_v_f64m4
#define VFMAXVV_FLOAT vfmax_vv_f64m4
#define VFADDVV_FLOAT vfadd_vv_f64m4
#define VFIRSTM vfirst_m_b16
#define UINT_V_T vuint64m4_t
#define VIDV_MASK_UINT vid_v_u64m4_m
#define VIDV_UINT vid_v_u64m4
#define VADDVX_MASK_UINT vadd_vx_u64m4_m
#define VADDVX_UINT vadd_vx_u64m4
#define VMVVX_UINT vmv_v_x_u64m4
#define VFMVFS_FLOAT_M1 vfmv_f_s_f64m1_f64
#define VSLIDEDOWN_UINT vslidedown_vx_u64m4
#define VMVVXS_UINT vmv_x_s_u64m4_u64
#else
#define VSETVL(n) vsetvl_e32m4(n)
#define VSETVL_MAX vsetvlmax_e32m4()
#define FLOAT_V_T vfloat32m4_t
#define FLOAT_V_T_M1 vfloat32m1_t
#define VLEV_FLOAT vle32_v_f32m4
#define VLSEV_FLOAT vlse32_v_f32m4
#define VLSEG_FLOAT vlseg2e32_v_f32m4
#define VLSSEG_FLOAT vlsseg2e32_v_f32m4
#define VFREDMAXVS_FLOAT vfredmax_vs_f32m4_f32m1
#define MASK_T vbool8_t
#define VMFLTVF_FLOAT vmflt_vf_f32m4_b8
#define VMFLTVV_FLOAT vmflt_vv_f32m4_b8
#define VMFGEVF_FLOAT vmfge_vf_f32m4_b8
#define VFMVVF_FLOAT vfmv_v_f_f32m4
#define VFMVVF_FLOAT_M1 vfmv_v_f_f32m1
#define VFABSV_FLOAT vfabs_v_f32m4
#define VFMAXVV_FLOAT vfmax_vv_f32m4
#define VFADDVV_FLOAT vfadd_vv_f32m4
#define VFIRSTM vfirst_m_b8
#define UINT_V_T vuint32m4_t
#define VIDV_MASK_UINT vid_v_u32m4_m
#define VIDV_UINT vid_v_u32m4
#define VADDVX_MASK_UINT vadd_vx_u32m4_m
#define VADDVX_UINT vadd_vx_u32m4
#define VMVVX_UINT vmv_v_x_u32m4
#define VFMVFS_FLOAT_M1 vfmv_f_s_f32m1_f32
#define VSLIDEDOWN_UINT vslidedown_vx_u32m4
#define VMVVXS_UINT vmv_x_s_u32m4_u32
#endif

BLASLONG CNAME(BLASLONG n, FLOAT *x, BLASLONG inc_x)
{
    unsigned int max_index = 0;
    if (n <= 0 || inc_x <= 0) return(max_index);

    FLOAT_V_T vx0, vx1, v_max;
    UINT_V_T v_max_index;
    MASK_T mask;
  
    size_t vlmax = VSETVL_MAX;
    v_max_index = VMVVX_UINT(0, vlmax);
    v_max = VFMVVF_FLOAT(-1, vlmax);
    BLASLONG j=0;
    FLOAT maxf=0.0;

    if(inc_x == 1) {

        for (size_t vl; n > 0; n -= vl, x += vl*2, j += vl) {
            vl = VSETVL(n);

            VLSEG_FLOAT(&vx0, &vx1, x, vl);

            vx0 = VFABSV_FLOAT(vx0, vl);
            vx1 = VFABSV_FLOAT(vx1, vl);

            vx0 = VFADDVV_FLOAT(vx0, vx1, vl);

            //index where element greater than v_max
            mask = VMFLTVV_FLOAT(v_max, vx0, vl);
            v_max_index = VIDV_MASK_UINT(mask, v_max_index, vl);
            v_max_index = VADDVX_MASK_UINT(mask, v_max_index, v_max_index, j, vl);

            //update v_max and start_index j
            v_max = VFMAXVV_FLOAT(v_max, vx0, vl);
        }
    }
    else {
        
        BLASLONG stride_x = inc_x * sizeof(FLOAT) * 2;
        for (size_t vl; n > 0; n -= vl, x += vl*inc_x*2, j += vl) {
            vl = VSETVL(n);
        
            VLSSEG_FLOAT(&vx0, &vx1, x, stride_x, vl);
        
            vx0 = VFABSV_FLOAT(vx0, vl);
            vx1 = VFABSV_FLOAT(vx1, vl);
        
            vx0 = VFADDVV_FLOAT(vx0, vx1, vl);
        
            //index where element greater than v_max
            mask = VMFLTVV_FLOAT(v_max, vx0, vl);
            v_max_index = VIDV_MASK_UINT(mask, v_max_index, vl);
            v_max_index = VADDVX_MASK_UINT(mask, v_max_index, v_max_index, j, vl);
        
            //update v_max and start_index j
            v_max = VFMAXVV_FLOAT(v_max, vx0, vl);
        }

    }
    FLOAT_V_T_M1 v_res, v_z0;
    v_res = VFMVVF_FLOAT_M1(0, vlmax);
    v_z0 = VFMVVF_FLOAT_M1(0, vlmax);

    v_res = VFREDMAXVS_FLOAT(v_res, v_max, v_z0, vlmax);
    maxf = VFMVFS_FLOAT_M1(v_res);
    mask = VMFGEVF_FLOAT(v_max, maxf, vlmax);
    max_index = VFIRSTM(mask, vlmax);
    
    v_max_index = VSLIDEDOWN_UINT(v_max_index, v_max_index, max_index, vlmax);
    max_index = VMVVXS_UINT(v_max_index);

    return(max_index+1);
}