// Copyright (c) 2026 Advanced Micro Devices, Inc.
// SPDX-License-Identifier: MIT

/// @file transcendental_test.cpp
/// @brief Phase C unit tests for shared transcendental functions.

#include "rocjitsu/isa/arch/amdgpu/shared/transcendental.h"

#include <gtest/gtest.h>

#include <bit>
#include <cmath>
#include <cstdint>
#include <limits>
#include <random>

namespace {

using namespace rocjitsu::amdgpu::transcendental;

// ---------------------------------------------------------------------------
// Special-case tests (±0, ±Inf, NaN, denormals)
// ---------------------------------------------------------------------------

TEST(TranscendentalTest, RcpF32SpecialCases) {
  EXPECT_EQ(rcp_f32(0.0f), std::numeric_limits<float>::infinity());
  EXPECT_EQ(rcp_f32(-0.0f), -std::numeric_limits<float>::infinity());
  EXPECT_EQ(rcp_f32(std::numeric_limits<float>::infinity()), 0.0f);
  EXPECT_EQ(rcp_f32(-std::numeric_limits<float>::infinity()), -0.0f);
  EXPECT_TRUE(std::isnan(rcp_f32(std::numeric_limits<float>::quiet_NaN())));
  EXPECT_FLOAT_EQ(rcp_f32(2.0f), 0.5f);
}

TEST(TranscendentalTest, RsqF32SpecialCases) {
  EXPECT_EQ(rsq_f32(0.0f), std::numeric_limits<float>::infinity());
  EXPECT_TRUE(std::isnan(rsq_f32(-1.0f)));
  EXPECT_EQ(rsq_f32(std::numeric_limits<float>::infinity()), 0.0f);
  EXPECT_TRUE(std::isnan(rsq_f32(std::numeric_limits<float>::quiet_NaN())));
  EXPECT_FLOAT_EQ(rsq_f32(4.0f), 0.5f);
}

TEST(TranscendentalTest, SqrtF32SpecialCases) {
  EXPECT_TRUE(std::isnan(sqrt_f32(-1.0f)));
  EXPECT_EQ(sqrt_f32(0.0f), 0.0f);
  EXPECT_EQ(sqrt_f32(std::numeric_limits<float>::infinity()),
            std::numeric_limits<float>::infinity());
  EXPECT_FLOAT_EQ(sqrt_f32(4.0f), 2.0f);
}

TEST(TranscendentalTest, LogF32SpecialCases) {
  EXPECT_EQ(log_f32(0.0f), -std::numeric_limits<float>::infinity());
  EXPECT_TRUE(std::isnan(log_f32(-1.0f)));
  EXPECT_EQ(log_f32(std::numeric_limits<float>::infinity()),
            std::numeric_limits<float>::infinity());
  EXPECT_FLOAT_EQ(log_f32(1.0f), 0.0f);
  EXPECT_FLOAT_EQ(log_f32(4.0f), 2.0f);
}

TEST(TranscendentalTest, ExpF32SpecialCases) {
  EXPECT_EQ(exp_f32(-std::numeric_limits<float>::infinity()), 0.0f);
  EXPECT_EQ(exp_f32(std::numeric_limits<float>::infinity()),
            std::numeric_limits<float>::infinity());
  EXPECT_FLOAT_EQ(exp_f32(0.0f), 1.0f);
  EXPECT_FLOAT_EQ(exp_f32(1.0f), 2.0f);
}

TEST(TranscendentalTest, SinCosF32SpecialCases) {
  // sin(2*pi*0) = 0, cos(2*pi*0) = 1
  EXPECT_NEAR(sin_f32(0.0f), 0.0f, 1e-6f);
  EXPECT_NEAR(cos_f32(0.0f), 1.0f, 1e-6f);
  // sin(2*pi*0.25) = 1, cos(2*pi*0.25) = 0
  EXPECT_NEAR(sin_f32(0.25f), 1.0f, 1e-6f);
  EXPECT_NEAR(cos_f32(0.25f), 0.0f, 1e-6f);
  // NaN/Inf inputs
  EXPECT_TRUE(std::isnan(sin_f32(std::numeric_limits<float>::infinity())));
  EXPECT_TRUE(std::isnan(cos_f32(std::numeric_limits<float>::infinity())));
}

TEST(TranscendentalTest, RcpF64SpecialCases) {
  EXPECT_EQ(rcp_f64(0.0), std::numeric_limits<double>::infinity());
  EXPECT_EQ(rcp_f64(-0.0), -std::numeric_limits<double>::infinity());
  EXPECT_DOUBLE_EQ(rcp_f64(2.0), 0.5);
}

TEST(TranscendentalTest, SqrtF64SpecialCases) {
  EXPECT_TRUE(std::isnan(sqrt_f64(-1.0)));
  EXPECT_DOUBLE_EQ(sqrt_f64(4.0), 2.0);
}

// ---------------------------------------------------------------------------
// ULP accuracy tests (pseudorandom inputs)
// ---------------------------------------------------------------------------

TEST(TranscendentalTest, RcpF32Ulp) {
  std::mt19937 rng(42);
  std::uniform_real_distribution<float> dist(0.001f, 1000.0f);
  for (int i = 0; i < 10000; ++i) {
    float x = dist(rng);
    float result = rcp_f32(x);
    float expected = 1.0f / x;
    // Allow 1 ULP difference
    ASSERT_NEAR(result, expected, std::abs(expected) * 1.2e-7f)
        << "rcp_f32(" << x << ") = " << result << " expected " << expected;
  }
}

TEST(TranscendentalTest, SqrtF32Ulp) {
  std::mt19937 rng(42);
  std::uniform_real_distribution<float> dist(0.0f, 1e6f);
  for (int i = 0; i < 10000; ++i) {
    float x = dist(rng);
    float result = sqrt_f32(x);
    float expected = std::sqrt(x);
    ASSERT_NEAR(result, expected, std::abs(expected) * 1.2e-7f)
        << "sqrt_f32(" << x << ") = " << result << " expected " << expected;
  }
}

} // namespace