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/*
* Copyright (c) 2022 EdgeImpulse Inc.
*
* 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.
*
* SPDX-License-Identifier: Apache-2.0
*/
#ifndef _EIDSP_SPEECHPY_FUNCTIONS_H_
#define _EIDSP_SPEECHPY_FUNCTIONS_H_
#include <math.h>
#include "../numpy.hpp"
#include "../returntypes.hpp"
namespace ei {
namespace speechpy {
class functions {
public:
/**
* Converting from frequency to Mel scale
*
* @param f The frequency values(or a single frequency) in Hz.
* @returns The mel scale values(or a single mel).
*/
static float frequency_to_mel(float f) {
#if EI_PORTING_RENESASRA65 == 1
return 1127.0 * log(1.0 + f / 700.0f);
#else
return 1127.0 * numpy::log((1.0 + f / 700.0f));
#endif
}
/**
* Converting from Mel scale to frequency.
*
* @param mel The mel scale values(or a single mel).
* @returns The frequency values(or a single frequency) in Hz.
*/
static float mel_to_frequency(float mel) {
return 700.0f * (exp(mel / 1127.0f) - 1.0f);
}
/**
* Triangle, linear scale from left up to middle, then down to right
* @param x Linspace output, will be overwritten!
* @param x_size Size of the linspace output
* @param left Starting index (assigned 0)
* @param middle Index where 1.0 will be placed
* @param right Ending index (assigned 0)
*/
static int triangle(float *x, size_t x_size, int left, int middle, int right) {
EI_DSP_MATRIX(out, 1, x_size);
for (size_t ix = 0; ix < x_size; ix++) {
if (x[ix] > left && x[ix] <= middle) {
out.buffer[ix] = (x[ix] - left) / (middle - left);
}
if (x[ix] < right && middle <= x[ix]) {
out.buffer[ix] = (right - x[ix]) / (right - middle);
}
}
memcpy(x, out.buffer, x_size * sizeof(float));
return EIDSP_OK;
}
};
} // namespace speechpy
} // namespace ei
#endif // _EIDSP_SPEECHPY_FUNCTIONS_H_
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