OpenBLAS/kernel/riscv64/znrm2_rvv.c

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#include "common.h"

#if !defined(DOUBLE)
#define VSETVL(n) vsetvl_e32m4(n)
#define VSETVL_MAX vsetvlmax_e32m4()
#define VSETVL_MAX_M1 vsetvlmax_e32m1()
#define FLOAT_V_T vfloat32m4_t
#define FLOAT_V_T_M1 vfloat32m1_t
#define VLSEG_FLOAT vlseg2e32_v_f32m4
#define VLSSEG_FLOAT vlsseg2e32_v_f32m4
#define VFREDSUM_FLOAT vfredusum_vs_f32m4_f32m1
#define VFMACCVV_FLOAT vfmacc_vv_f32m4
#define VFMVVF_FLOAT vfmv_v_f_f32m4
#define VFMVVF_FLOAT_M1 vfmv_v_f_f32m1
#define VFREDMAXVS_FLOAT vfredmax_vs_f32m4_f32m1
#define VFMVFS_FLOAT_M1 vfmv_f_s_f32m1_f32
#define VFABSV_FLOAT vfabs_v_f32m4
#else
#define VSETVL(n) vsetvl_e64m4(n)
#define VSETVL_MAX vsetvlmax_e64m4()
#define VSETVL_MAX_M1 vsetvlmax_e64m1()
#define FLOAT_V_T vfloat64m4_t
#define FLOAT_V_T_M1 vfloat64m1_t
#define VLSEG_FLOAT vlseg2e64_v_f64m4
#define VLSSEG_FLOAT vlsseg2e64_v_f64m4
#define VFREDSUM_FLOAT vfredusum_vs_f64m4_f64m1
#define VFMACCVV_FLOAT vfmacc_vv_f64m4
#define VFMVVF_FLOAT vfmv_v_f_f64m4
#define VFMVVF_FLOAT_M1 vfmv_v_f_f64m1
#define VFREDMAXVS_FLOAT vfredmax_vs_f64m4_f64m1
#define VFMVFS_FLOAT_M1 vfmv_f_s_f64m1_f64
#define VFABSV_FLOAT vfabs_v_f64m4
#endif

// TODO: Should single precision use the widening MAC, or perhaps all should be double? 

FLOAT CNAME(BLASLONG n, FLOAT *x, BLASLONG inc_x)
{

    if ( n <= 0 ) return(0.0);

    FLOAT_V_T vr, v0, v1;
    FLOAT_V_T_M1 v_max, v_res;
    FLOAT scale = 0.0, ssq = 0.0;

    size_t vlmax = VSETVL_MAX;
    v_res = VFMVVF_FLOAT_M1(0, vlmax);
    v_max = VFMVVF_FLOAT_M1(0, vlmax);

    vr = VFMVVF_FLOAT(0, vlmax);

    if (inc_x == 1) {

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

            VLSEG_FLOAT(&v0, &v1, x, vl);
            v0 = VFABSV_FLOAT(v0, vl);
            v1 = VFABSV_FLOAT(v1, vl);

            v_max = VFREDMAXVS_FLOAT(v_max, v0, v_max, vl);
            vr = VFMACCVV_FLOAT(vr, v0, v0, vl);

            v_max = VFREDMAXVS_FLOAT(v_max, v1, v_max, vl);
            vr = VFMACCVV_FLOAT(vr, v1, v1, vl);
        }

    } else {

        BLASLONG stride_x = inc_x * sizeof(FLOAT) * 2;

        for (size_t vl; n > 0; n -= vl, x += vl*inc_x*2) {
            vl = VSETVL(n);
 
            VLSSEG_FLOAT(&v0, &v1, x, stride_x, vl);
            v0 = VFABSV_FLOAT(v0, vl);
            v1 = VFABSV_FLOAT(v1, vl);

            v_max = VFREDMAXVS_FLOAT(v_max, v0, v_max, vl);
            vr = VFMACCVV_FLOAT(vr, v0, v0, vl);

            v_max = VFREDMAXVS_FLOAT(v_max, v1, v_max, vl);
            vr = VFMACCVV_FLOAT(vr, v1, v1, vl);
        }

    }

    v_res = VFREDSUM_FLOAT(v_res, vr, v_res, vlmax);

    ssq = VFMVFS_FLOAT_M1(v_res);
    scale = VFMVFS_FLOAT_M1(v_max);
    ssq = ssq / (scale*scale);

    return(scale * sqrt(ssq));
}