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- #include "arm_math.h"
- void arm_var_q31(
- q31_t * pSrc,
- uint32_t blockSize,
- q31_t * pResult)
- {
- q63_t sum = 0;
- q63_t meanOfSquares, squareOfMean;
- q31_t in;
- uint32_t blkCnt;
- q63_t sumOfSquares = 0;
- if(blockSize == 1)
- {
- *pResult = 0;
- return;
- }
-
- #ifndef ARM_MATH_CM0_FAMILY
-
-
- blkCnt = blockSize >> 2u;
-
- while(blkCnt > 0u)
- {
-
-
- in = *pSrc++ >> 8;
- sum += in;
- sumOfSquares += ((q63_t) (in) * (in));
- in = *pSrc++ >> 8;
- sum += in;
- sumOfSquares += ((q63_t) (in) * (in));
- in = *pSrc++ >> 8;
- sum += in;
- sumOfSquares += ((q63_t) (in) * (in));
- in = *pSrc++ >> 8;
- sum += in;
- sumOfSquares += ((q63_t) (in) * (in));
-
- blkCnt--;
- }
-
- blkCnt = blockSize % 0x4u;
- while(blkCnt > 0u)
- {
-
-
- in = *pSrc++ >> 8;
- sum += in;
- sumOfSquares += ((q63_t) (in) * (in));
-
- blkCnt--;
- }
-
- meanOfSquares = sumOfSquares / (q63_t)(blockSize - 1);
- #else
-
-
- blkCnt = blockSize;
- while(blkCnt > 0u)
- {
-
-
- in = *pSrc++ >> 8;
- sumOfSquares += ((q63_t) (in) * (in));
-
-
- sum += in;
-
- blkCnt--;
- }
-
- meanOfSquares = sumOfSquares / (q63_t)(blockSize - 1);
- #endif
-
- squareOfMean = sum * sum / (q63_t)(blockSize * (blockSize - 1u));
-
- *pResult = (meanOfSquares - squareOfMean) >> 15;
- }
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