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/* ----------------------------------------------------------------------
* Project: CMSIS DSP Library
* Title: arm_dct4_init_q31.c
* Description: Initialization function of DCT-4 & IDCT4 Q31
*
* $Date: 18. March 2019
* $Revision: V1.6.0
*
* Target Processor: Cortex-M cores
* -------------------------------------------------------------------- */
/*
* Copyright (C) 2010-2019 ARM Limited or its affiliates. All rights reserved.
*
* SPDX-License-Identifier: Apache-2.0
*
* 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
*
* 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 "arm_math.h"
#include "arm_common_tables.h"
/**
@ingroup DCT4_IDCT4
*/
/**
@addtogroup DCT4_IDCT4
@{
*/
/**
@brief Initialization function for the Q31 DCT4/IDCT4.
@param[in,out] S points to an instance of Q31 DCT4/IDCT4 structure.
@param[in] S_RFFT points to an instance of Q31 RFFT/RIFFT structure
@param[in] S_CFFT points to an instance of Q31 CFFT/CIFFT structure
@param[in] N length of the DCT4.
@param[in] Nby2 half of the length of the DCT4.
@param[in] normalize normalizing factor.
@return execution status
- \ref ARM_MATH_SUCCESS : Operation successful
- \ref ARM_MATH_ARGUMENT_ERROR : <code>N</code> is not a supported transform length
@par Normalizing factor:
The normalizing factor is <code>sqrt(2/N)</code>, which depends on the size of transform <code>N</code>.
Normalizing factors in 1.31 format are mentioned in the table below for different DCT sizes:
\image html dct4NormalizingQ31Table.gif
*/
arm_status arm_dct4_init_q31(
arm_dct4_instance_q31 * S,
arm_rfft_instance_q31 * S_RFFT,
arm_cfft_radix4_instance_q31 * S_CFFT,
uint16_t N,
uint16_t Nby2,
q31_t normalize)
{
/* Initialize the default arm status */
arm_status status = ARM_MATH_SUCCESS;
/* Initialize the DCT4 length */
S->N = N;
/* Initialize the half of DCT4 length */
S->Nby2 = Nby2;
/* Initialize the DCT4 Normalizing factor */
S->normalize = normalize;
/* Initialize Real FFT Instance */
S->pRfft = S_RFFT;
/* Initialize Complex FFT Instance */
S->pCfft = S_CFFT;
switch (N)
{
#if !defined(ARM_DSP_CONFIG_TABLES) || defined(ARM_ALL_FFT_TABLES) || defined(ARM_TABLE_DCT4_Q31_8192)
/* Initialize the table modifier values */
case 8192U:
S->pTwiddle = WeightsQ31_8192;
S->pCosFactor = cos_factorsQ31_8192;
break;
#endif
#if !defined(ARM_DSP_CONFIG_TABLES) || defined(ARM_ALL_FFT_TABLES) || defined(ARM_TABLE_DCT4_Q31_2048)
case 2048U:
S->pTwiddle = WeightsQ31_2048;
S->pCosFactor = cos_factorsQ31_2048;
break;
#endif
#if !defined(ARM_DSP_CONFIG_TABLES) || defined(ARM_ALL_FFT_TABLES) || defined(ARM_TABLE_DCT4_Q31_512)
case 512U:
S->pTwiddle = WeightsQ31_512;
S->pCosFactor = cos_factorsQ31_512;
break;
#endif
#if !defined(ARM_DSP_CONFIG_TABLES) || defined(ARM_ALL_FFT_TABLES) || defined(ARM_TABLE_DCT4_Q31_128)
case 128U:
S->pTwiddle = WeightsQ31_128;
S->pCosFactor = cos_factorsQ31_128;
break;
#endif
default:
status = ARM_MATH_ARGUMENT_ERROR;
}
/* Initialize the RFFT/RIFFT Function */
arm_rfft_init_q31(S->pRfft, S->N, 0U, 1U);
/* return the status of DCT4 Init function */
return (status);
}
/**
@} end of DCT4_IDCT4 group
*/
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