Rev 49 | Details | Compare with Previous | Last modification | View Log | RSS feed
| Rev | Author | Line No. | Line |
|---|---|---|---|
| 2 | mjames | 1 | /* ---------------------------------------------------------------------- |
| 2 | * Copyright (C) 2010-2014 ARM Limited. All rights reserved. |
||
| 3 | * |
||
| 4 | * $Date: 19. March 2015 |
||
| 5 | * $Revision: V.1.4.5 |
||
| 6 | * |
||
| 7 | * Project: CMSIS DSP Library |
||
| 8 | * Title: arm_dct4_init_q31.c |
||
| 9 | * |
||
| 10 | * Description: Initialization function of DCT-4 & IDCT4 Q31 |
||
| 11 | * |
||
| 12 | * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0 |
||
| 13 | * |
||
| 14 | * Redistribution and use in source and binary forms, with or without |
||
| 15 | * modification, are permitted provided that the following conditions |
||
| 16 | * are met: |
||
| 17 | * - Redistributions of source code must retain the above copyright |
||
| 18 | * notice, this list of conditions and the following disclaimer. |
||
| 19 | * - Redistributions in binary form must reproduce the above copyright |
||
| 20 | * notice, this list of conditions and the following disclaimer in |
||
| 21 | * the documentation and/or other materials provided with the |
||
| 22 | * distribution. |
||
| 23 | * - Neither the name of ARM LIMITED nor the names of its contributors |
||
| 24 | * may be used to endorse or promote products derived from this |
||
| 25 | * software without specific prior written permission. |
||
| 26 | * |
||
| 27 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
||
| 28 | * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
||
| 29 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
||
| 30 | * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
||
| 31 | * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, |
||
| 32 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, |
||
| 33 | * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
||
| 34 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER |
||
| 35 | * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
||
| 36 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN |
||
| 37 | * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
||
| 38 | * POSSIBILITY OF SUCH DAMAGE. |
||
| 39 | * -------------------------------------------------------------------- */ |
||
| 40 | |||
| 41 | |||
| 42 | #include "arm_math.h" |
||
| 43 | |||
| 44 | /** |
||
| 45 | * @ingroup groupTransforms |
||
| 46 | */ |
||
| 47 | |||
| 48 | /** |
||
| 49 | * @addtogroup DCT4_IDCT4 |
||
| 50 | * @{ |
||
| 51 | */ |
||
| 52 | |||
| 53 | /* |
||
| 54 | * @brief Weights Table |
||
| 55 | */ |
||
| 56 | |||
| 57 | /** |
||
| 58 | * \par |
||
| 59 | * Weights tables are generated using the formula : <pre>weights[n] = e^(-j*n*pi/(2*N))</pre> |
||
| 60 | * \par |
||
| 61 | * C command to generate the table |
||
| 62 | * <pre> |
||
| 63 | * for(i = 0; i< N; i++) |
||
| 64 | * { |
||
| 65 | * weights[2*i]= cos(i*c); |
||
| 66 | * weights[(2*i)+1]= -sin(i * c); |
||
| 67 | * } </pre> |
||
| 68 | * \par |
||
| 69 | * where <code>N</code> is the Number of weights to be calculated and <code>c</code> is <code>pi/(2*N)</code> |
||
| 70 | * \par |
||
| 71 | * Convert the output to q31 format by multiplying with 2^31 and saturated if required. |
||
| 72 | * \par |
||
| 73 | * In the tables below the real and imaginary values are placed alternatively, hence the |
||
| 74 | * array length is <code>2*N</code>. |
||
| 75 | *//** |
||
| 76 | |||
| 77 | * cosFactor tables are generated using the formula : <pre>cos_factors[n] = 2 * cos((2n+1)*pi/(4*N))</pre> |
||
| 78 | * \par |
||
| 79 | * C command to generate the table |
||
| 80 | * <pre> |
||
| 81 | * for(i = 0; i< N; i++) |
||
| 82 | * { |
||
| 83 | * cos_factors[i]= 2 * cos((2*i+1)*c/2); |
||
| 84 | * } </pre> |
||
| 85 | * \par |
||
| 86 | * where <code>N</code> is the number of factors to generate and <code>c</code> is <code>pi/(2*N)</code> |
||
| 87 | * \par |
||
| 88 | * Then converted to q31 format by multiplying with 2^31 and saturated if required. |
||
| 89 | *//** |
||
| 90 | * @brief Initialization function for the Q31 DCT4/IDCT4. |
||
| 91 | * @param[in,out] *S points to an instance of Q31 DCT4/IDCT4 structure. |
||
| 92 | * @param[in] *S_RFFT points to an instance of Q31 RFFT/RIFFT structure |
||
| 93 | * @param[in] *S_CFFT points to an instance of Q31 CFFT/CIFFT structure |
||
| 94 | * @param[in] N length of the DCT4. |
||
| 95 | * @param[in] Nby2 half of the length of the DCT4. |
||
| 96 | * @param[in] normalize normalizing factor. |
||
| 97 | * @return arm_status function returns ARM_MATH_SUCCESS if initialization is successful or ARM_MATH_ARGUMENT_ERROR if <code>N</code> is not a supported transform length. |
||
| 98 | * \par Normalizing factor: |
||
| 99 | * The normalizing factor is <code>sqrt(2/N)</code>, which depends on the size of transform <code>N</code>. |
||
| 100 | * Normalizing factors in 1.31 format are mentioned in the table below for different DCT sizes: |
||
| 101 | * \image html dct4NormalizingQ31Table.gif |
||
| 102 | */ |
||
| 103 | |||
| 104 | arm_status arm_dct4_init_q31( |
||
| 105 | arm_dct4_instance_q31 * S, |
||
| 106 | arm_rfft_instance_q31 * S_RFFT, |
||
| 107 | arm_cfft_radix4_instance_q31 * S_CFFT, |
||
| 108 | uint16_t N, |
||
| 109 | uint16_t Nby2, |
||
| 110 | q31_t normalize) |
||
| 111 | { |
||
| 112 | /* Initialise the default arm status */ |
||
| 113 | arm_status status = ARM_MATH_SUCCESS; |
||
| 114 | |||
| 115 | /* Initializing the pointer array with the weight table base addresses of different lengths */ |
||
| 116 | q31_t *twiddlePtr[4] = { (q31_t *) WeightsQ31_128, (q31_t *) WeightsQ31_512, |
||
| 117 | (q31_t *) WeightsQ31_2048, (q31_t *) WeightsQ31_8192 |
||
| 118 | }; |
||
| 119 | |||
| 120 | /* Initializing the pointer array with the cos factor table base addresses of different lengths */ |
||
| 121 | q31_t *pCosFactor[4] = |
||
| 122 | { (q31_t *) cos_factorsQ31_128, (q31_t *) cos_factorsQ31_512, |
||
| 123 | (q31_t *) cos_factorsQ31_2048, (q31_t *) cos_factorsQ31_8192 |
||
| 124 | }; |
||
| 125 | |||
| 126 | /* Initialize the DCT4 length */ |
||
| 127 | S->N = N; |
||
| 128 | |||
| 129 | /* Initialize the half of DCT4 length */ |
||
| 130 | S->Nby2 = Nby2; |
||
| 131 | |||
| 132 | /* Initialize the DCT4 Normalizing factor */ |
||
| 133 | S->normalize = normalize; |
||
| 134 | |||
| 135 | /* Initialize Real FFT Instance */ |
||
| 136 | S->pRfft = S_RFFT; |
||
| 137 | |||
| 138 | /* Initialize Complex FFT Instance */ |
||
| 139 | S->pCfft = S_CFFT; |
||
| 140 | |||
| 141 | switch (N) |
||
| 142 | { |
||
| 143 | |||
| 144 | case 8192u: |
||
| 145 | S->pTwiddle = twiddlePtr[3]; |
||
| 146 | S->pCosFactor = pCosFactor[3]; |
||
| 147 | break; |
||
| 148 | case 2048u: |
||
| 149 | S->pTwiddle = twiddlePtr[2]; |
||
| 150 | S->pCosFactor = pCosFactor[2]; |
||
| 151 | break; |
||
| 152 | case 512u: |
||
| 153 | S->pTwiddle = twiddlePtr[1]; |
||
| 154 | S->pCosFactor = pCosFactor[1]; |
||
| 155 | break; |
||
| 156 | case 128u: |
||
| 157 | S->pTwiddle = twiddlePtr[0]; |
||
| 158 | S->pCosFactor = pCosFactor[0]; |
||
| 159 | break; |
||
| 160 | default: |
||
| 161 | status = ARM_MATH_ARGUMENT_ERROR; |
||
| 162 | } |
||
| 163 | |||
| 164 | /* Initialize the RFFT/RIFFT Function */ |
||
| 165 | arm_rfft_init_q31(S->pRfft, S->N, 0, 1); |
||
| 166 | |||
| 167 | /* return the status of DCT4 Init function */ |
||
| 168 | return (status); |
||
| 169 | } |
||
| 170 | |||
| 171 | /** |
||
| 172 | * @} end of DCT4_IDCT4 group |
||
| 173 | */ |
||
| 174 | |||
| 175 |