#include "log2_ln.hpp"
#include <cstring>
#include <cmath>

namespace soothe2 {

float ln_plugin_f32(float x) {
    if (x <= 0.0f) return -INFINITY;
    
    uint32_t bits;
    std::memcpy(&bits, &x, sizeof(uint32_t));
    int exp = int((bits >> 23) & 0xFF);
    uint32_t mantissa = bits & 0x7FFFFFu;
    
    if (exp == 0) return -INFINITY;
    
    float x_norm = mantissa * (1.0f / 8388608.0f);
    
    constexpr float c0_a = -0.1517720520f;
    constexpr float c0_b =  0.1696488112f;
    constexpr float c1   = -0.1646245718f;
    constexpr float c2   =  0.1982250363f;
    constexpr float c3   = -0.2500466406f;
    constexpr float c4   =  0.3333656490f;
    constexpr float c5   = -0.5000000000f;
    constexpr float ln2  =  0.6931471825f;
    
    constexpr float c0_init = c0_a * c0_b;
    
    float y = c0_init + x_norm;
    y = y * x_norm + c1;
    y = y * x_norm + c2;
    y = y * x_norm + c3;
    y = y * x_norm + c4;
    y = y * x_norm + c5;
    
    float ln_m = x_norm + x_norm * x_norm * y;
    
    return ln2 * float(exp - 127) + ln_m;
}

void ln_plugin_f32_arr(const float* in, float* out, size_t n) {
    for (size_t i = 0; i < n; ++i) {
        out[i] = ln_plugin_f32(in[i]);
    }
}

}  // namespace soothe2