// SPDX-FileCopyrightText: © 2026 Vladimir Zorin <vladimir@deviant.guru>
// SPDX-License-Identifier: LicenseRef-OWL-1.0-or-later
// Licensed under OWL v1.0+. See LICENSE.

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

/* Simple loops — the compiler auto-vectorizes these to SSE/AVX on x86_64.
   No hand-written SIMD needed for the expected scale (<100K vectors). */

float mneme_vec_dot(const float *a, const float *b, int dim) {
    float sum = 0.0f;
    for (int i = 0; i < dim; i++)
        sum += a[i] * b[i];
    return sum;
}

float mneme_vec_cosine(const float *a, const float *b, int dim) {
    float dot = 0.0f, na = 0.0f, nb = 0.0f;
    for (int i = 0; i < dim; i++) {
        dot += a[i] * b[i];
        na += a[i] * a[i];
        nb += b[i] * b[i];
    }
    float denom = sqrtf(na) * sqrtf(nb);
    if (denom < 1e-30f)
        return 1.0f; /* degenerate: treat as orthogonal */
    return 1.0f - dot / denom;
}

float mneme_vec_l2(const float *a, const float *b, int dim) {
    float sum = 0.0f;
    for (int i = 0; i < dim; i++) {
        float d = a[i] - b[i];
        sum += d * d;
    }
    return sqrtf(sum);
}

void mneme_vec_normalize(float *v, int dim) {
    float sum = 0.0f;
    for (int i = 0; i < dim; i++)
        sum += v[i] * v[i];
    float inv = 1.0f / sqrtf(sum);
    if (!isfinite(inv))
        return;
    for (int i = 0; i < dim; i++)
        v[i] *= inv;
}