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authorAli Labbene <ali.labbene@st.com>2019-12-11 08:59:21 +0100
committerAli Labbene <ali.labbene@st.com>2019-12-16 16:35:24 +0100
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Official ARM version: v5.4.0
Add CMSIS V5.4.0, please refer to index.html available under \docs folder. Note: content of \CMSIS\Core\Include has been copied under \Include to keep the same structure used in existing projects, and thus avoid projects mass update Note: the following components have been removed from ARM original delivery (as not used in ST packages) - CMSIS_EW2018.pdf - .gitattributes - .gitignore - \Device - \CMSIS - \CoreValidation - \DAP - \Documentation - \DoxyGen - \Driver - \Pack - \RTOS\CMSIS_RTOS_Tutorial.pdf - \RTOS\RTX - \RTOS\Template - \RTOS2\RTX - \Utilities - All ARM/GCC projects files are deleted from \DSP, \RTOS and \RTOS2 Change-Id: Ia026c3f0f0d016627a4fb5a9032852c33d24b4d3
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+/* ----------------------------------------------------------------------
+ * Project: CMSIS DSP Library
+ * Title: arm_rms_q15.c
+ * Description: Root Mean Square of the elements of a Q15 vector
+ *
+ * $Date: 27. January 2017
+ * $Revision: V.1.5.1
+ *
+ * Target Processor: Cortex-M cores
+ * -------------------------------------------------------------------- */
+/*
+ * Copyright (C) 2010-2017 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 "arm_math.h"
+
+/**
+ * @addtogroup RMS
+ * @{
+ */
+
+/**
+ * @brief Root Mean Square of the elements of a Q15 vector.
+ * @param[in] *pSrc points to the input vector
+ * @param[in] blockSize length of the input vector
+ * @param[out] *pResult rms value returned here
+ * @return none.
+ *
+ * @details
+ * <b>Scaling and Overflow Behavior:</b>
+ *
+ * \par
+ * The function is implemented using a 64-bit internal accumulator.
+ * The input is represented in 1.15 format.
+ * Intermediate multiplication yields a 2.30 format, and this
+ * result is added without saturation to a 64-bit accumulator in 34.30 format.
+ * With 33 guard bits in the accumulator, there is no risk of overflow, and the
+ * full precision of the intermediate multiplication is preserved.
+ * Finally, the 34.30 result is truncated to 34.15 format by discarding the lower
+ * 15 bits, and then saturated to yield a result in 1.15 format.
+ *
+ */
+
+void arm_rms_q15(
+ q15_t * pSrc,
+ uint32_t blockSize,
+ q15_t * pResult)
+{
+ q63_t sum = 0; /* accumulator */
+
+#if defined (ARM_MATH_DSP)
+ /* Run the below code for Cortex-M4 and Cortex-M3 */
+
+ q31_t in; /* temporary variable to store the input value */
+ q15_t in1; /* temporary variable to store the input value */
+ uint32_t blkCnt; /* loop counter */
+
+ /* 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] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1]) */
+ /* Compute sum of the squares and then store the results in a temporary variable, sum */
+ in = *__SIMD32(pSrc)++;
+ sum = __SMLALD(in, in, sum);
+ in = *__SIMD32(pSrc)++;
+ sum = __SMLALD(in, in, sum);
+
+ /* 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;
+
+ while (blkCnt > 0U)
+ {
+ /* C = (A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1]) */
+ /* Compute sum of the squares and then store the results in a temporary variable, sum */
+ in1 = *pSrc++;
+ sum = __SMLALD(in1, in1, sum);
+
+ /* Decrement the loop counter */
+ blkCnt--;
+ }
+
+ /* Truncating and saturating the accumulator to 1.15 format */
+ /* Store the result in the destination */
+ arm_sqrt_q15(__SSAT((sum / (q63_t)blockSize) >> 15, 16), pResult);
+
+#else
+ /* Run the below code for Cortex-M0 */
+
+ q15_t in; /* temporary variable to store the input value */
+ uint32_t blkCnt; /* loop counter */
+
+ /* Loop over blockSize number of values */
+ blkCnt = blockSize;
+
+ while (blkCnt > 0U)
+ {
+ /* C = (A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1]) */
+ /* Compute sum of the squares and then store the results in a temporary variable, sum */
+ in = *pSrc++;
+ sum += ((q31_t) in * in);
+
+ /* Decrement the loop counter */
+ blkCnt--;
+ }
+
+ /* Truncating and saturating the accumulator to 1.15 format */
+ /* Store the result in the destination */
+ arm_sqrt_q15(__SSAT((sum / (q63_t)blockSize) >> 15, 16), pResult);
+
+#endif /* #if defined (ARM_MATH_DSP) */
+
+}
+
+/**
+ * @} end of RMS group
+ */