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- /* ----------------------------------------------------------------------------
- * Copyright (C) 2010-2013 ARM Limited. All rights reserved.
- *
- * $Date: 17. January 2013
- * $Revision: V1.4.1
- *
- * Project: CMSIS DSP Library
- * Title: arm_q15_to_q7.c
- *
- * Description: Converts the elements of the Q15 vector to Q7 vector.
- *
- * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * - Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * - Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in
- * the documentation and/or other materials provided with the
- * distribution.
- * - Neither the name of ARM LIMITED nor the names of its contributors
- * may be used to endorse or promote products derived from this
- * software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
- * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
- * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
- * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
- * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
- * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- * ---------------------------------------------------------------------------- */
-
- #include "arm_math.h"
-
- /**
- * @ingroup groupSupport
- */
-
- /**
- * @addtogroup q15_to_x
- * @{
- */
-
-
- /**
- * @brief Converts the elements of the Q15 vector to Q7 vector.
- * @param[in] *pSrc points to the Q15 input vector
- * @param[out] *pDst points to the Q7 output vector
- * @param[in] blockSize length of the input vector
- * @return none.
- *
- * \par Description:
- *
- * The equation used for the conversion process is:
- *
- * <pre>
- * pDst[n] = (q7_t) pSrc[n] >> 8; 0 <= n < blockSize.
- * </pre>
- *
- */
-
-
- void arm_q15_to_q7(
- q15_t * pSrc,
- q7_t * pDst,
- uint32_t blockSize)
- {
- q15_t *pIn = pSrc; /* Src pointer */
- uint32_t blkCnt; /* loop counter */
-
- #ifndef ARM_MATH_CM0_FAMILY
-
- /* Run the below code for Cortex-M4 and Cortex-M3 */
- q31_t in1, in2;
- q31_t out1, out2;
-
- /*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 = (q7_t) A >> 8 */
- /* convert from q15 to q7 and then store the results in the destination buffer */
- in1 = *__SIMD32(pIn)++;
- in2 = *__SIMD32(pIn)++;
-
- #ifndef ARM_MATH_BIG_ENDIAN
-
- out1 = __PKHTB(in2, in1, 16);
- out2 = __PKHBT(in2, in1, 16);
-
- #else
-
- out1 = __PKHTB(in1, in2, 16);
- out2 = __PKHBT(in1, in2, 16);
-
- #endif // #ifndef ARM_MATH_BIG_ENDIAN
-
- /* rotate packed value by 24 */
- out2 = ((uint32_t) out2 << 8) | ((uint32_t) out2 >> 24);
-
- /* anding with 0xff00ff00 to get two 8 bit values */
- out1 = out1 & 0xFF00FF00;
- /* anding with 0x00ff00ff to get two 8 bit values */
- out2 = out2 & 0x00FF00FF;
-
- /* oring two values(contains two 8 bit values) to get four packed 8 bit values */
- out1 = out1 | out2;
-
- /* store 4 samples at a time to destiantion buffer */
- *__SIMD32(pDst)++ = out1;
-
- /* 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;
-
- #else
-
- /* Run the below code for Cortex-M0 */
-
- /* Loop over blockSize number of values */
- blkCnt = blockSize;
-
- #endif /* #ifndef ARM_MATH_CM0_FAMILY */
-
- while(blkCnt > 0u)
- {
- /* C = (q7_t) A >> 8 */
- /* convert from q15 to q7 and then store the results in the destination buffer */
- *pDst++ = (q7_t) (*pIn++ >> 8);
-
- /* Decrement the loop counter */
- blkCnt--;
- }
-
- }
-
- /**
- * @} end of q15_to_x group
- */
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