pebble/tests/libc/math/test_pow.c

/*
 * Copyright 2024 Google LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <stdint.h>
#include <string.h>
#include <stdio.h>
#include <limits.h>
#include <math.h>
#include <fenv.h>

#include "clar.h"

double pow_theirs(double x, double y) {
  return pow(x,y);
}

// "Define" libc functions we're testing
#include "pblibc_private.h"

void test_pow__initialize(void) {
  fesetround(FE_TONEAREST);
}

///////////////////////////////////////////////////////////////////////////////////////////////////
//! Tests

void test_pow__basic(void) {
  for(int i = 0; i < 10000; i++) {
    double v = i * 0.001;
    double us = pow(2, v);
    double them = pow_theirs(2,v);

    // 1 ulps is acceptable error
    // To actually check this, we need to do some sorta gross raw operations on the doubles
    int64_t diff = *(int64_t*)&us - *(int64_t*)&them;
    cl_assert(diff <= 1 && diff >= -1);
  }
}