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| 56 | mjames | 1 | /* ---------------------------------------------------------------------- |
| 2 | * Project: CMSIS DSP Library |
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| 3 | * Title: arm_dot_prod_q31.c |
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| 4 | * Description: Q31 dot product |
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| 5 | * |
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| 6 | * $Date: 27. January 2017 |
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| 7 | * $Revision: V.1.5.1 |
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| 8 | * |
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| 9 | * Target Processor: Cortex-M cores |
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| 10 | * -------------------------------------------------------------------- */ |
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| 11 | /* |
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| 12 | * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved. |
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| 13 | * |
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| 14 | * SPDX-License-Identifier: Apache-2.0 |
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| 15 | * |
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| 16 | * Licensed under the Apache License, Version 2.0 (the License); you may |
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| 17 | * not use this file except in compliance with the License. |
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| 18 | * You may obtain a copy of the License at |
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| 19 | * |
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| 20 | * www.apache.org/licenses/LICENSE-2.0 |
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| 21 | * |
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| 22 | * Unless required by applicable law or agreed to in writing, software |
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| 23 | * distributed under the License is distributed on an AS IS BASIS, WITHOUT |
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| 24 | * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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| 25 | * See the License for the specific language governing permissions and |
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| 26 | * limitations under the License. |
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| 27 | */ |
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| 28 | |||
| 29 | #include "arm_math.h" |
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| 30 | |||
| 31 | /** |
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| 32 | * @ingroup groupMath |
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| 33 | */ |
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| 34 | |||
| 35 | /** |
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| 36 | * @addtogroup dot_prod |
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| 37 | * @{ |
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| 38 | */ |
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| 39 | |||
| 40 | /** |
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| 41 | * @brief Dot product of Q31 vectors. |
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| 42 | * @param[in] *pSrcA points to the first input vector |
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| 43 | * @param[in] *pSrcB points to the second input vector |
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| 44 | * @param[in] blockSize number of samples in each vector |
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| 45 | * @param[out] *result output result returned here |
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| 46 | * @return none. |
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| 47 | * |
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| 48 | * <b>Scaling and Overflow Behavior:</b> |
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| 49 | * \par |
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| 50 | * The intermediate multiplications are in 1.31 x 1.31 = 2.62 format and these |
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| 51 | * are truncated to 2.48 format by discarding the lower 14 bits. |
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| 52 | * The 2.48 result is then added without saturation to a 64-bit accumulator in 16.48 format. |
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| 53 | * There are 15 guard bits in the accumulator and there is no risk of overflow as long as |
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| 54 | * the length of the vectors is less than 2^16 elements. |
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| 55 | * The return result is in 16.48 format. |
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| 56 | */ |
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| 57 | |||
| 58 | void arm_dot_prod_q31( |
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| 59 | q31_t * pSrcA, |
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| 60 | q31_t * pSrcB, |
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| 61 | uint32_t blockSize, |
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| 62 | q63_t * result) |
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| 63 | { |
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| 64 | q63_t sum = 0; /* Temporary result storage */ |
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| 65 | uint32_t blkCnt; /* loop counter */ |
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| 66 | |||
| 67 | |||
| 68 | #if defined (ARM_MATH_DSP) |
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| 69 | |||
| 70 | /* Run the below code for Cortex-M4 and Cortex-M3 */ |
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| 71 | q31_t inA1, inA2, inA3, inA4; |
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| 72 | q31_t inB1, inB2, inB3, inB4; |
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| 73 | |||
| 74 | /*loop Unrolling */ |
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| 75 | blkCnt = blockSize >> 2U; |
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| 76 | |||
| 77 | /* First part of the processing with loop unrolling. Compute 4 outputs at a time. |
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| 78 | ** a second loop below computes the remaining 1 to 3 samples. */ |
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| 79 | while (blkCnt > 0U) |
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| 80 | { |
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| 81 | /* C = A[0]* B[0] + A[1]* B[1] + A[2]* B[2] + .....+ A[blockSize-1]* B[blockSize-1] */ |
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| 82 | /* Calculate dot product and then store the result in a temporary buffer. */ |
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| 83 | inA1 = *pSrcA++; |
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| 84 | inA2 = *pSrcA++; |
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| 85 | inA3 = *pSrcA++; |
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| 86 | inA4 = *pSrcA++; |
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| 87 | inB1 = *pSrcB++; |
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| 88 | inB2 = *pSrcB++; |
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| 89 | inB3 = *pSrcB++; |
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| 90 | inB4 = *pSrcB++; |
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| 91 | |||
| 92 | sum += ((q63_t) inA1 * inB1) >> 14U; |
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| 93 | sum += ((q63_t) inA2 * inB2) >> 14U; |
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| 94 | sum += ((q63_t) inA3 * inB3) >> 14U; |
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| 95 | sum += ((q63_t) inA4 * inB4) >> 14U; |
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| 96 | |||
| 97 | /* Decrement the loop counter */ |
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| 98 | blkCnt--; |
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| 99 | } |
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| 100 | |||
| 101 | /* If the blockSize is not a multiple of 4, compute any remaining output samples here. |
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| 102 | ** No loop unrolling is used. */ |
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| 103 | blkCnt = blockSize % 0x4U; |
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| 104 | |||
| 105 | #else |
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| 106 | |||
| 107 | /* Run the below code for Cortex-M0 */ |
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| 108 | |||
| 109 | /* Initialize blkCnt with number of samples */ |
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| 110 | blkCnt = blockSize; |
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| 111 | |||
| 112 | #endif /* #if defined (ARM_MATH_DSP) */ |
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| 113 | |||
| 114 | |||
| 115 | while (blkCnt > 0U) |
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| 116 | { |
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| 117 | /* C = A[0]* B[0] + A[1]* B[1] + A[2]* B[2] + .....+ A[blockSize-1]* B[blockSize-1] */ |
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| 118 | /* Calculate dot product and then store the result in a temporary buffer. */ |
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| 119 | sum += ((q63_t) * pSrcA++ * *pSrcB++) >> 14U; |
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| 120 | |||
| 121 | /* Decrement the loop counter */ |
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| 122 | blkCnt--; |
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| 123 | } |
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| 124 | |||
| 125 | /* Store the result in the destination buffer in 16.48 format */ |
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| 126 | *result = sum; |
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| 127 | } |
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| 128 | |||
| 129 | /** |
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| 130 | * @} end of dot_prod group |
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| 131 | */ |