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+/* ----------------------------------------------------------------------
+ * 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
+ */