| /* ---------------------------------------------------------------------- |
| * Project: CMSIS DSP Library |
| * Title: arm_shift_q7.c |
| * Description: Processing function for the Q7 Shifting |
| * |
| * $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" |
| |
| /** |
| * @ingroup groupMath |
| */ |
| |
| /** |
| * @addtogroup shift |
| * @{ |
| */ |
| |
| |
| /** |
| * @brief Shifts the elements of a Q7 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 Conditions for optimum performance |
| * Input and output buffers should be aligned by 32-bit |
| * |
| * |
| * <b>Scaling and Overflow Behavior:</b> |
| * \par |
| * The function uses saturating arithmetic. |
| * Results outside of the allowable Q7 range [0x8 0x7F] will be saturated. |
| */ |
| |
| void arm_shift_q7( |
| q7_t * pSrc, |
| int8_t shiftBits, |
| q7_t * pDst, |
| uint32_t blockSize) |
| { |
| uint32_t blkCnt; /* loop counter */ |
| uint8_t sign; /* Sign of shiftBits */ |
| |
| #if defined (ARM_MATH_DSP) |
| |
| /* Run the below code for Cortex-M4 and Cortex-M3 */ |
| q7_t in1; /* Input value1 */ |
| q7_t in2; /* Input value2 */ |
| q7_t in3; /* Input value3 */ |
| q7_t in4; /* Input value4 */ |
| |
| |
| /*loop Unrolling */ |
| blkCnt = blockSize >> 2U; |
| |
| /* Getting the sign of shiftBits */ |
| sign = (shiftBits & 0x80); |
| |
| /* If the shift value is positive then do right shift else left shift */ |
| if (sign == 0U) |
| { |
| /* 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 << shiftBits */ |
| /* Read 4 inputs */ |
| in1 = *pSrc; |
| in2 = *(pSrc + 1); |
| in3 = *(pSrc + 2); |
| in4 = *(pSrc + 3); |
| |
| /* Store the Shifted result in the destination buffer in single cycle by packing the outputs */ |
| *__SIMD32(pDst)++ = __PACKq7(__SSAT((in1 << shiftBits), 8), |
| __SSAT((in2 << shiftBits), 8), |
| __SSAT((in3 << shiftBits), 8), |
| __SSAT((in4 << shiftBits), 8)); |
| /* Update source pointer to process next sampels */ |
| pSrc += 4U; |
| |
| /* 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 << shiftBits */ |
| /* Shift the input and then store the result in the destination buffer. */ |
| *pDst++ = (q7_t) __SSAT((*pSrc++ << shiftBits), 8); |
| |
| /* Decrement the loop counter */ |
| blkCnt--; |
| } |
| } |
| else |
| { |
| shiftBits = -shiftBits; |
| /* 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 >> shiftBits */ |
| /* Read 4 inputs */ |
| in1 = *pSrc; |
| in2 = *(pSrc + 1); |
| in3 = *(pSrc + 2); |
| in4 = *(pSrc + 3); |
| |
| /* Store the Shifted result in the destination buffer in single cycle by packing the outputs */ |
| *__SIMD32(pDst)++ = __PACKq7((in1 >> shiftBits), (in2 >> shiftBits), |
| (in3 >> shiftBits), (in4 >> shiftBits)); |
| |
| |
| pSrc += 4U; |
| |
| /* 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 >> shiftBits */ |
| /* Shift the input and then store the result in the destination buffer. */ |
| in1 = *pSrc++; |
| *pDst++ = (in1 >> shiftBits); |
| |
| /* Decrement the loop counter */ |
| blkCnt--; |
| } |
| } |
| |
| #else |
| |
| /* Run the below code for Cortex-M0 */ |
| |
| /* Getting the sign of shiftBits */ |
| sign = (shiftBits & 0x80); |
| |
| /* If the shift value is positive then do right shift else left shift */ |
| if (sign == 0U) |
| { |
| /* Initialize blkCnt with number of samples */ |
| blkCnt = blockSize; |
| |
| while (blkCnt > 0U) |
| { |
| /* C = A << shiftBits */ |
| /* Shift the input and then store the result in the destination buffer. */ |
| *pDst++ = (q7_t) __SSAT(((q15_t) * pSrc++ << shiftBits), 8); |
| |
| /* Decrement the loop counter */ |
| blkCnt--; |
| } |
| } |
| else |
| { |
| /* Initialize blkCnt with number of samples */ |
| blkCnt = blockSize; |
| |
| while (blkCnt > 0U) |
| { |
| /* C = A >> shiftBits */ |
| /* Shift the input and then store the result in the destination buffer. */ |
| *pDst++ = (*pSrc++ >> -shiftBits); |
| |
| /* Decrement the loop counter */ |
| blkCnt--; |
| } |
| } |
| |
| #endif /* #if defined (ARM_MATH_DSP) */ |
| } |
| |
| /** |
| * @} end of shift group |
| */ |