1 /* ----------------------------------------------------------------------
2 * Copyright (C) 2010 ARM Limited. All rights reserved.
7 * Project: CMSIS DSP Library
8 * Title: arm_cmplx_dot_prod_q31.c
10 * Description: Q31 complex dot product
12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
14 * Version 1.0.10 2011/7/15
15 * Big Endian support added and Merged M0 and M3/M4 Source code.
17 * Version 1.0.3 2010/11/29
18 * Re-organized the CMSIS folders and updated documentation.
20 * Version 1.0.2 2010/11/11
21 * Documentation updated.
23 * Version 1.0.1 2010/10/05
24 * Production release and review comments incorporated.
26 * Version 1.0.0 2010/09/20
27 * Production release and review comments incorporated.
28 * -------------------------------------------------------------------- */
33 * @ingroup groupCmplxMath
37 * @addtogroup cmplx_dot_prod
42 * @brief Q31 complex dot product
43 * @param *pSrcA points to the first input vector
44 * @param *pSrcB points to the second input vector
45 * @param numSamples number of complex samples in each vector
46 * @param *realResult real part of the result returned here
47 * @param *imagResult imaginary part of the result returned here
50 * <b>Scaling and Overflow Behavior:</b>
52 * The function is implemented using an internal 64-bit accumulator.
53 * The intermediate 1.31 by 1.31 multiplications are performed with 64-bit precision and then shifted to 16.48 format.
54 * The internal real and imaginary accumulators are in 16.48 format and provide 15 guard bits.
55 * Additions are nonsaturating and no overflow will occur as long as <code>numSamples</code> is less than 32768.
56 * The return results <code>realResult</code> and <code>imagResult</code> are in 16.48 format.
57 * Input down scaling is not required.
60 void arm_cmplx_dot_prod_q31(
67 q63_t real_sum = 0, imag_sum = 0; /* Temporary result storage */
71 /* Run the below code for Cortex-M4 and Cortex-M3 */
72 uint32_t blkCnt; /* loop counter */
76 blkCnt = numSamples >> 2u;
78 /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
79 ** a second loop below computes the remaining 1 to 3 samples. */
82 /* CReal = A[0]* B[0] + A[2]* B[2] + A[4]* B[4] + .....+ A[numSamples-2]* B[numSamples-2] */
83 /* Convert real data in 2.62 to 16.48 by 14 right shifts */
84 real_sum += (q63_t) * pSrcA++ * (*pSrcB++) >> 14;
85 /* CImag = A[1]* B[1] + A[3]* B[3] + A[5]* B[5] + .....+ A[numSamples-1]* B[numSamples-1] */
86 /* Convert imag data in 2.62 to 16.48 by 14 right shifts */
87 imag_sum += (q63_t) * pSrcA++ * (*pSrcB++) >> 14;
89 real_sum += (q63_t) * pSrcA++ * (*pSrcB++) >> 14;
90 imag_sum += (q63_t) * pSrcA++ * (*pSrcB++) >> 14;
92 real_sum += (q63_t) * pSrcA++ * (*pSrcB++) >> 14;
93 imag_sum += (q63_t) * pSrcA++ * (*pSrcB++) >> 14;
95 real_sum += (q63_t) * pSrcA++ * (*pSrcB++) >> 14;
96 imag_sum += (q63_t) * pSrcA++ * (*pSrcB++) >> 14;
99 /* Decrement the loop counter */
103 /* If the numSamples is not a multiple of 4, compute any remaining output samples here.
104 ** No loop unrolling is used. */
105 blkCnt = numSamples % 0x4u;
109 /* CReal = A[0]* B[0] + A[2]* B[2] + A[4]* B[4] + .....+ A[numSamples-2]* B[numSamples-2] */
110 real_sum += (q63_t) * pSrcA++ * (*pSrcB++) >> 14;
111 /* CImag = A[1]* B[1] + A[3]* B[3] + A[5]* B[5] + .....+ A[numSamples-1]* B[numSamples-1] */
112 imag_sum += (q63_t) * pSrcA++ * (*pSrcB++) >> 14;
114 /* Decrement the loop counter */
120 /* Run the below code for Cortex-M0 */
122 while(numSamples > 0u)
124 /* outReal = realA[0]* realB[0] + realA[2]* realB[2] + realA[4]* realB[4] + .....+ realA[numSamples-2]* realB[numSamples-2] */
125 real_sum += (q63_t) * pSrcA++ * (*pSrcB++) >> 14;
126 /* outImag = imagA[1]* imagB[1] + imagA[3]* imagB[3] + imagA[5]* imagB[5] + .....+ imagA[numSamples-1]* imagB[numSamples-1] */
127 imag_sum += (q63_t) * pSrcA++ * (*pSrcB++) >> 14;
129 /* Decrement the loop counter */
133 #endif /* #ifndef ARM_MATH_CM0 */
135 /* Store the real and imaginary results in 16.48 format */
136 *realResult = real_sum;
137 *imagResult = imag_sum;
141 * @} end of cmplx_dot_prod group