pigweed / third_party / github / STMicroelectronics / cmsis_core / 7dd288b23bf605a3a2fafa81a29d2c96a2fd83ce / . / DSP_Lib / Source / BasicMathFunctions / arm_dot_prod_q31.c

/* ---------------------------------------------------------------------- | |

* Copyright (C) 2010-2014 ARM Limited. All rights reserved. | |

* | |

* $Date: 19. March 2015 | |

* $Revision: V.1.4.5 | |

* | |

* Project: CMSIS DSP Library | |

* Title: arm_dot_prod_q31.c | |

* | |

* Description: Q31 dot product. | |

* | |

* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0 | |

* | |

* Redistribution and use in source and binary forms, with or without | |

* modification, are permitted provided that the following conditions | |

* are met: | |

* - Redistributions of source code must retain the above copyright | |

* notice, this list of conditions and the following disclaimer. | |

* - Redistributions in binary form must reproduce the above copyright | |

* notice, this list of conditions and the following disclaimer in | |

* the documentation and/or other materials provided with the | |

* distribution. | |

* - Neither the name of ARM LIMITED nor the names of its contributors | |

* may be used to endorse or promote products derived from this | |

* software without specific prior written permission. | |

* | |

* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | |

* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | |

* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS | |

* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE | |

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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; | |

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* -------------------------------------------------------------------- */ | |

#include "arm_math.h" | |

/** | |

* @ingroup groupMath | |

*/ | |

/** | |

* @addtogroup dot_prod | |

* @{ | |

*/ | |

/** | |

* @brief Dot product of Q31 vectors. | |

* @param[in] *pSrcA points to the first input vector | |

* @param[in] *pSrcB points to the second input vector | |

* @param[in] blockSize number of samples in each vector | |

* @param[out] *result output result returned here | |

* @return none. | |

* | |

* <b>Scaling and Overflow Behavior:</b> | |

* \par | |

* The intermediate multiplications are in 1.31 x 1.31 = 2.62 format and these | |

* are truncated to 2.48 format by discarding the lower 14 bits. | |

* The 2.48 result is then added without saturation to a 64-bit accumulator in 16.48 format. | |

* There are 15 guard bits in the accumulator and there is no risk of overflow as long as | |

* the length of the vectors is less than 2^16 elements. | |

* The return result is in 16.48 format. | |

*/ | |

void arm_dot_prod_q31( | |

q31_t * pSrcA, | |

q31_t * pSrcB, | |

uint32_t blockSize, | |

q63_t * result) | |

{ | |

q63_t sum = 0; /* Temporary result storage */ | |

uint32_t blkCnt; /* loop counter */ | |

#ifndef ARM_MATH_CM0_FAMILY | |

/* Run the below code for Cortex-M4 and Cortex-M3 */ | |

q31_t inA1, inA2, inA3, inA4; | |

q31_t inB1, inB2, inB3, inB4; | |

/*loop Unrolling */ | |

blkCnt = blockSize >> 2u; | |

/* First part of the processing with loop unrolling. Compute 4 outputs at a time. | |

** a second loop below computes the remaining 1 to 3 samples. */ | |

while(blkCnt > 0u) | |

{ | |

/* C = A[0]* B[0] + A[1]* B[1] + A[2]* B[2] + .....+ A[blockSize-1]* B[blockSize-1] */ | |

/* Calculate dot product and then store the result in a temporary buffer. */ | |

inA1 = *pSrcA++; | |

inA2 = *pSrcA++; | |

inA3 = *pSrcA++; | |

inA4 = *pSrcA++; | |

inB1 = *pSrcB++; | |

inB2 = *pSrcB++; | |

inB3 = *pSrcB++; | |

inB4 = *pSrcB++; | |

sum += ((q63_t) inA1 * inB1) >> 14u; | |

sum += ((q63_t) inA2 * inB2) >> 14u; | |

sum += ((q63_t) inA3 * inB3) >> 14u; | |

sum += ((q63_t) inA4 * inB4) >> 14u; | |

/* Decrement the loop counter */ | |

blkCnt--; | |

} | |

/* If the blockSize is not a multiple of 4, compute any remaining output samples here. | |

** No loop unrolling is used. */ | |

blkCnt = blockSize % 0x4u; | |

#else | |

/* Run the below code for Cortex-M0 */ | |

/* Initialize blkCnt with number of samples */ | |

blkCnt = blockSize; | |

#endif /* #ifndef ARM_MATH_CM0_FAMILY */ | |

while(blkCnt > 0u) | |

{ | |

/* C = A[0]* B[0] + A[1]* B[1] + A[2]* B[2] + .....+ A[blockSize-1]* B[blockSize-1] */ | |

/* Calculate dot product and then store the result in a temporary buffer. */ | |

sum += ((q63_t) * pSrcA++ * *pSrcB++) >> 14u; | |

/* Decrement the loop counter */ | |

blkCnt--; | |

} | |

/* Store the result in the destination buffer in 16.48 format */ | |

*result = sum; | |

} | |

/** | |

* @} end of dot_prod group | |

*/ |