/* ---------------------------------------------------------------------- * Project: CMSIS DSP Library * Title: arm_q31_to_q7.c * Description: Converts the elements of the Q31 vector to Q7 vector * * $Date: 18. March 2019 * $Revision: V1.6.0 * * Target Processor: Cortex-M cores * -------------------------------------------------------------------- */ /* * Copyright (C) 2010-2019 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" /** @ingroup groupSupport */ /** @addtogroup q31_to_x @{ */ /** @brief Converts the elements of the Q31 vector to Q7 vector. @param[in] pSrc points to the Q31 input vector @param[out] pDst points to the Q7 output vector @param[in] blockSize number of samples in each vector @return none @par Details The equation used for the conversion process is:
      pDst[n] = (q7_t) pSrc[n] >> 24;   0 <= n < blockSize.
  
*/ void arm_q31_to_q7( const q31_t * pSrc, q7_t * pDst, uint32_t blockSize) { uint32_t blkCnt; /* Loop counter */ const q31_t *pIn = pSrc; /* Source pointer */ #if defined (ARM_MATH_LOOPUNROLL) q7_t out1, out2, out3, out4; /* Loop unrolling: Compute 4 outputs at a time */ blkCnt = blockSize >> 2U; while (blkCnt > 0U) { /* C = (q7_t) (A >> 24) */ /* Convert from q31 to q7 and store result in destination buffer */ out1 = (q7_t) (*pIn++ >> 24); out2 = (q7_t) (*pIn++ >> 24); out3 = (q7_t) (*pIn++ >> 24); out4 = (q7_t) (*pIn++ >> 24); write_q7x4_ia (&pDst, __PACKq7(out1, out2, out3, out4)); /* 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) */ while (blkCnt > 0U) { /* C = (q7_t) (A >> 24) */ /* Convert from q31 to q7 and store result in destination buffer */ *pDst++ = (q7_t) (*pIn++ >> 24); /* Decrement loop counter */ blkCnt--; } } /** @} end of q31_to_x group */