lib/main/CMSIS/DSP/Source/ComplexMathFunctions/arm_cmplx_conj_f32.c

   1 /* ----------------------------------------------------------------------
   2  * Project:      CMSIS DSP Library
   3  * Title:        arm_cmplx_conj_f32.c
   4  * Description:  Floating-point complex conjugate
   5  *
   6  * $Date:        27. January 2017
   7  * $Revision:    V.1.5.1
   8  *
   9  * Target Processor: Cortex-M cores
  10  * -------------------------------------------------------------------- */
  11 /*
  12  * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved.
  13  *
  14  * SPDX-License-Identifier: Apache-2.0
  15  *
  16  * Licensed under the Apache License, Version 2.0 (the License); you may
  17  * not use this file except in compliance with the License.
  18  * You may obtain a copy of the License at
  19  *
  20  * www.apache.org/licenses/LICENSE-2.0
  21  *
  22  * Unless required by applicable law or agreed to in writing, software
  23  * distributed under the License is distributed on an AS IS BASIS, WITHOUT
  24  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  25  * See the License for the specific language governing permissions and
  26  * limitations under the License.
  27  */
  28
  29 #include "arm_math.h"
  30
  31 /**
  32  * @ingroup groupCmplxMath
  33  */
  34
  35 /**
  36  * @defgroup cmplx_conj Complex Conjugate
  37  *
  38  * Conjugates the elements of a complex data vector.
  39  *
  40  * The <code>pSrc</code> points to the source data and
  41  * <code>pDst</code> points to the where the result should be written.
  42  * <code>numSamples</code> specifies the number of complex samples
  43  * and the data in each array is stored in an interleaved fashion
  44  * (real, imag, real, imag, ...).
  45  * Each array has a total of <code>2*numSamples</code> values.
  46  * The underlying algorithm is used:
  47  *
  48  * <pre>
  49  * for(n=0; n<numSamples; n++) {
  50  *     pDst[(2*n)+0)] = pSrc[(2*n)+0];     // real part
  51  *     pDst[(2*n)+1)] = -pSrc[(2*n)+1];    // imag part
  52  * }
  53  * </pre>
  54  *
  55  * There are separate functions for floating-point, Q15, and Q31 data types.
  56  */
  57
  58 /**
  59  * @addtogroup cmplx_conj
  60  * @{
  61  */
  62
  63 /**
  64  * @brief  Floating-point complex conjugate.
  65  * @param  *pSrc points to the input vector
  66  * @param  *pDst points to the output vector
  67  * @param  numSamples number of complex samples in each vector
  68  * @return none.
  69  */
  70
  71 void arm_cmplx_conj_f32(
  72   float32_t * pSrc,
  73   float32_t * pDst,
  74   uint32_t numSamples)
  75 {
  76   uint32_t blkCnt;                               /* loop counter */
  77
  78 #if defined (ARM_MATH_DSP)
  79
  80   /* Run the below code for Cortex-M4 and Cortex-M3 */
  81   float32_t inR1, inR2, inR3, inR4;
  82   float32_t inI1, inI2, inI3, inI4;
  83
  84   /*loop Unrolling */
  85   blkCnt = numSamples >> 2U;
  86
  87   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
  88    ** a second loop below computes the remaining 1 to 3 samples. */
  89   while (blkCnt > 0U)
  90   {
  91     /* C[0]+jC[1] = A[0]+ j (-1) A[1] */
  92     /* Calculate Complex Conjugate and then store the results in the destination buffer. */
  93     /* read real input samples */
  94     inR1 = pSrc[0];
  95     /* store real samples to destination */
  96     pDst[0] = inR1;
  97     inR2 = pSrc[2];
  98     pDst[2] = inR2;
  99     inR3 = pSrc[4];
 100     pDst[4] = inR3;
 101     inR4 = pSrc[6];
 102     pDst[6] = inR4;
 103
 104     /* read imaginary input samples */
 105     inI1 = pSrc[1];
 106     inI2 = pSrc[3];
 107
 108     /* conjugate input */
 109     inI1 = -inI1;
 110
 111     /* read imaginary input samples */
 112     inI3 = pSrc[5];
 113
 114     /* conjugate input */
 115     inI2 = -inI2;
 116
 117     /* read imaginary input samples */
 118     inI4 = pSrc[7];
 119
 120     /* conjugate input */
 121     inI3 = -inI3;
 122
 123     /* store imaginary samples to destination */
 124     pDst[1] = inI1;
 125     pDst[3] = inI2;
 126
 127     /* conjugate input */
 128     inI4 = -inI4;
 129
 130     /* store imaginary samples to destination */
 131     pDst[5] = inI3;
 132
 133     /* increment source pointer by 8 to process next sampels */
 134     pSrc += 8U;
 135
 136     /* store imaginary sample to destination */
 137     pDst[7] = inI4;
 138
 139     /* increment destination pointer by 8 to store next samples */
 140     pDst += 8U;
 141
 142     /* Decrement the loop counter */
 143     blkCnt--;
 144   }
 145
 146   /* If the numSamples is not a multiple of 4, compute any remaining output samples here.
 147    ** No loop unrolling is used. */
 148   blkCnt = numSamples % 0x4U;
 149
 150 #else
 151
 152   /* Run the below code for Cortex-M0 */
 153   blkCnt = numSamples;
 154
 155 #endif /* #if defined (ARM_MATH_DSP) */
 156
 157   while (blkCnt > 0U)
 158   {
 159     /* realOut + j (imagOut) = realIn + j (-1) imagIn */
 160     /* Calculate Complex Conjugate and then store the results in the destination buffer. */
 161     *pDst++ = *pSrc++;
 162     *pDst++ = -*pSrc++;
 163
 164     /* Decrement the loop counter */
 165     blkCnt--;
 166   }
 167 }
 168
 169 /**
 170  * @} end of cmplx_conj group
 171  */