| /* ---------------------------------------------------------------------- |
| * Project: CMSIS DSP Library |
| * Title: arm_dct4_init_q15.c |
| * Description: Initialization function of DCT-4 & IDCT4 Q15 |
| * |
| * $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 Q15 DCT4/IDCT4. |
| @param[in,out] S points to an instance of Q15 DCT4/IDCT4 structure |
| @param[in] S_RFFT points to an instance of Q15 RFFT/RIFFT structure |
| @param[in] S_CFFT points to an instance of Q15 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 1.15 format are mentioned in the table below for different DCT sizes: |
| |
| \image html dct4NormalizingQ15Table.gif |
| */ |
| |
| arm_status arm_dct4_init_q15( |
| arm_dct4_instance_q15 * S, |
| arm_rfft_instance_q15 * S_RFFT, |
| arm_cfft_radix4_instance_q15 * S_CFFT, |
| uint16_t N, |
| uint16_t Nby2, |
| q15_t normalize) |
| { |
| /* Initialise 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_Q15_8192) |
| /* Initialize the table modifier values */ |
| case 8192U: |
| S->pTwiddle = WeightsQ15_8192; |
| S->pCosFactor = cos_factorsQ15_8192; |
| break; |
| #endif |
| |
| #if !defined(ARM_DSP_CONFIG_TABLES) || defined(ARM_ALL_FFT_TABLES) || defined(ARM_TABLE_DCT4_Q15_2048) |
| case 2048U: |
| S->pTwiddle = WeightsQ15_2048; |
| S->pCosFactor = cos_factorsQ15_2048; |
| break; |
| #endif |
| |
| #if !defined(ARM_DSP_CONFIG_TABLES) || defined(ARM_ALL_FFT_TABLES) || defined(ARM_TABLE_DCT4_Q15_512) |
| case 512U: |
| S->pTwiddle = WeightsQ15_512; |
| S->pCosFactor = cos_factorsQ15_512; |
| break; |
| #endif |
| |
| #if !defined(ARM_DSP_CONFIG_TABLES) || defined(ARM_ALL_FFT_TABLES) || defined(ARM_TABLE_DCT4_Q15_128) |
| case 128U: |
| S->pTwiddle = WeightsQ15_128; |
| S->pCosFactor = cos_factorsQ15_128; |
| break; |
| #endif |
| |
| default: |
| status = ARM_MATH_ARGUMENT_ERROR; |
| } |
| |
| /* Initialize the RFFT/RIFFT */ |
| arm_rfft_init_q15(S->pRfft, S->N, 0U, 1U); |
| |
| /* return the status of DCT4 Init function */ |
| return (status); |
| } |
| |
| /** |
| @} end of DCT4_IDCT4 group |
| */ |