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authorClyne Sullivan <clyne@bitgloo.com>2025-01-29 21:34:25 -0500
committerClyne Sullivan <clyne@bitgloo.com>2025-01-29 21:34:25 -0500
commit5b81bc8ccbd342b8566d88fc9f17a73aec03b5b6 (patch)
treecc57486912cfa74c6440d8b97c28f451ec787d78 /Drivers/CMSIS/DSP/Source/BasicMathFunctions/arm_shift_q31.c
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+/* ----------------------------------------------------------------------
+ * Project: CMSIS DSP Library
+ * Title: arm_shift_q31.c
+ * Description: Shifts the elements of a Q31 vector by a specified number of bits
+ *
+ * $Date: 23 April 2021
+ * $Revision: V1.9.0
+ *
+ * Target Processor: Cortex-M and Cortex-A cores
+ * -------------------------------------------------------------------- */
+/*
+ * Copyright (C) 2010-2021 ARM Limited or its affiliates. All rights reserved.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 (the License); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an AS IS BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "dsp/basic_math_functions.h"
+
+/**
+ @ingroup groupMath
+ */
+/**
+ @defgroup BasicShift Vector Shift
+
+ Shifts the elements of a fixed-point vector by a specified number of bits.
+ There are separate functions for Q7, Q15, and Q31 data types.
+ The underlying algorithm used is:
+
+ <pre>
+ pDst[n] = pSrc[n] << shift, 0 <= n < blockSize.
+ </pre>
+
+ If <code>shift</code> is positive then the elements of the vector are shifted to the left.
+ If <code>shift</code> is negative then the elements of the vector are shifted to the right.
+
+ The functions support in-place computation allowing the source and destination
+ pointers to reference the same memory buffer.
+ */
+
+/**
+ @addtogroup BasicShift
+ @{
+ */
+
+/**
+ @brief Shifts the elements of a Q31 vector a specified number of bits.
+ @param[in] pSrc points to the input vector
+ @param[in] shiftBits number of bits to shift. A positive value shifts left; a negative value shifts right.
+ @param[out] pDst points to the output vector
+ @param[in] blockSize number of samples in the vector
+ @return none
+
+ @par Scaling and Overflow Behavior
+ The function uses saturating arithmetic.
+ Results outside of the allowable Q31 range [0x80000000 0x7FFFFFFF] are saturated.
+ */
+
+#if defined(ARM_MATH_MVEI) && !defined(ARM_MATH_AUTOVECTORIZE)
+
+#include "arm_helium_utils.h"
+
+void arm_shift_q31(
+ const q31_t * pSrc,
+ int8_t shiftBits,
+ q31_t * pDst,
+ uint32_t blockSize)
+{
+ uint32_t blkCnt; /* loop counters */
+ q31x4_t vecSrc;
+ q31x4_t vecDst;
+
+ /* Compute 4 outputs at a time */
+ blkCnt = blockSize >> 2;
+ while (blkCnt > 0U)
+ {
+ /*
+ * C = A (>> or <<) shiftBits
+ * Shift the input and then store the result in the destination buffer.
+ */
+ vecSrc = vld1q((q31_t const *) pSrc);
+ vecDst = vqshlq_r(vecSrc, shiftBits);
+ vst1q(pDst, vecDst);
+ /*
+ * Decrement the blockSize loop counter
+ */
+ blkCnt--;
+ /*
+ * advance vector source and destination pointers
+ */
+ pSrc += 4;
+ pDst += 4;
+ }
+ /*
+ * tail
+ */
+ blkCnt = blockSize & 3;
+ if (blkCnt > 0U)
+ {
+ mve_pred16_t p0 = vctp32q(blkCnt);
+ vecSrc = vld1q((q31_t const *) pSrc);
+ vecDst = vqshlq_r(vecSrc, shiftBits);
+ vstrwq_p(pDst, vecDst, p0);
+ }
+}
+
+
+#else
+void arm_shift_q31(
+ const q31_t * pSrc,
+ int8_t shiftBits,
+ q31_t * pDst,
+ uint32_t blockSize)
+{
+ uint32_t blkCnt; /* Loop counter */
+ uint8_t sign = (shiftBits & 0x80); /* Sign of shiftBits */
+
+#if defined (ARM_MATH_LOOPUNROLL)
+
+ q31_t in, out; /* Temporary variables */
+
+ /* Loop unrolling: Compute 4 outputs at a time */
+ blkCnt = blockSize >> 2U;
+
+ /* If the shift value is positive then do right shift else left shift */
+ if (sign == 0U)
+ {
+ while (blkCnt > 0U)
+ {
+ /* C = A << shiftBits */
+
+ /* Shift input and store result in destination buffer. */
+ in = *pSrc++;
+ out = in << shiftBits;
+ if (in != (out >> shiftBits))
+ out = 0x7FFFFFFF ^ (in >> 31);
+ *pDst++ = out;
+
+ in = *pSrc++;
+ out = in << shiftBits;
+ if (in != (out >> shiftBits))
+ out = 0x7FFFFFFF ^ (in >> 31);
+ *pDst++ = out;
+
+ in = *pSrc++;
+ out = in << shiftBits;
+ if (in != (out >> shiftBits))
+ out = 0x7FFFFFFF ^ (in >> 31);
+ *pDst++ = out;
+
+ in = *pSrc++;
+ out = in << shiftBits;
+ if (in != (out >> shiftBits))
+ out = 0x7FFFFFFF ^ (in >> 31);
+ *pDst++ = out;
+
+ /* Decrement loop counter */
+ blkCnt--;
+ }
+ }
+ else
+ {
+ while (blkCnt > 0U)
+ {
+ /* C = A >> shiftBits */
+
+ /* Shift input and store results in destination buffer. */
+ *pDst++ = (*pSrc++ >> -shiftBits);
+ *pDst++ = (*pSrc++ >> -shiftBits);
+ *pDst++ = (*pSrc++ >> -shiftBits);
+ *pDst++ = (*pSrc++ >> -shiftBits);
+
+ /* Decrement loop counter */
+ blkCnt--;
+ }
+ }
+
+ /* Loop unrolling: Compute remaining outputs */
+ blkCnt = blockSize % 0x4U;
+
+#else
+
+ /* Initialize blkCnt with number of samples */
+ blkCnt = blockSize;
+
+#endif /* #if defined (ARM_MATH_LOOPUNROLL) */
+
+ /* If the shift value is positive then do right shift else left shift */
+ if (sign == 0U)
+ {
+ while (blkCnt > 0U)
+ {
+ /* C = A << shiftBits */
+
+ /* Shift input and store result in destination buffer. */
+ *pDst++ = clip_q63_to_q31((q63_t) *pSrc++ << shiftBits);
+
+ /* Decrement loop counter */
+ blkCnt--;
+ }
+ }
+ else
+ {
+ while (blkCnt > 0U)
+ {
+ /* C = A >> shiftBits */
+
+ /* Shift input and store result in destination buffer. */
+ *pDst++ = (*pSrc++ >> -shiftBits);
+
+ /* Decrement loop counter */
+ blkCnt--;
+ }
+ }
+
+}
+#endif /* defined(ARM_MATH_MVEI) */
+
+/**
+ @} end of BasicShift group
+ */
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