ebiten/audio/internal/oboe/oboe_flowgraph_resampler_IntegerRatio_android.cpp

51 lines
1.6 KiB
C++
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/*
* Copyright 2019 The Android Open Source Project
*
* 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 "oboe_flowgraph_resampler_IntegerRatio_android.h"
using namespace resampler;
// Enough primes to cover the common sample rates.
static const int kPrimes[] = {
2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41,
43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97,
101, 103, 107, 109, 113, 127, 131, 137, 139, 149,
151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199};
void IntegerRatio::reduce() {
for (int prime : kPrimes) {
if (mNumerator < prime || mDenominator < prime) {
break;
}
// Find biggest prime factor for numerator.
while (true) {
int top = mNumerator / prime;
int bottom = mDenominator / prime;
if ((top >= 1)
&& (bottom >= 1)
&& (top * prime == mNumerator) // divided evenly?
&& (bottom * prime == mDenominator)) {
mNumerator = top;
mDenominator = bottom;
} else {
break;
}
}
}
}