| /* ---------------------------------------------------------------------- |
| * Project: CMSIS DSP Library |
| * Title: arm_scale_q7.c |
| * Description: Multiplies a Q7 vector by a scalar |
| * |
| * $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 groupMath |
| */ |
| |
| /** |
| @addtogroup BasicScale |
| @{ |
| */ |
| |
| /** |
| @brief Multiplies a Q7 vector by a scalar. |
| @param[in] pSrc points to the input vector |
| @param[in] scaleFract fractional portion of the scale value |
| @param[in] shift number of bits to shift the result by |
| @param[out] pDst points to the output vector |
| @param[in] blockSize number of samples in each vector |
| @return none |
| |
| @par Scaling and Overflow Behavior |
| The input data <code>*pSrc</code> and <code>scaleFract</code> are in 1.7 format. |
| These are multiplied to yield a 2.14 intermediate result and this is shifted with saturation to 1.7 format. |
| */ |
| |
| void arm_scale_q7( |
| const q7_t * pSrc, |
| q7_t scaleFract, |
| int8_t shift, |
| q7_t * pDst, |
| uint32_t blockSize) |
| { |
| uint32_t blkCnt; /* Loop counter */ |
| int8_t kShift = 7 - shift; /* Shift to apply after scaling */ |
| |
| #if defined (ARM_MATH_LOOPUNROLL) |
| |
| #if defined (ARM_MATH_DSP) |
| q7_t in1, in2, in3, in4; /* Temporary input variables */ |
| q7_t out1, out2, out3, out4; /* Temporary output variables */ |
| #endif |
| |
| /* Loop unrolling: Compute 4 outputs at a time */ |
| blkCnt = blockSize >> 2U; |
| |
| while (blkCnt > 0U) |
| { |
| /* C = A * scale */ |
| |
| #if defined (ARM_MATH_DSP) |
| /* Reading 4 inputs from memory */ |
| in1 = *pSrc++; |
| in2 = *pSrc++; |
| in3 = *pSrc++; |
| in4 = *pSrc++; |
| |
| /* Scale inputs and store result in the temporary variable. */ |
| out1 = (q7_t) (__SSAT(((in1) * scaleFract) >> kShift, 8)); |
| out2 = (q7_t) (__SSAT(((in2) * scaleFract) >> kShift, 8)); |
| out3 = (q7_t) (__SSAT(((in3) * scaleFract) >> kShift, 8)); |
| out4 = (q7_t) (__SSAT(((in4) * scaleFract) >> kShift, 8)); |
| |
| /* Pack and store result in destination buffer (in single write) */ |
| write_q7x4_ia (&pDst, __PACKq7(out1, out2, out3, out4)); |
| #else |
| *pDst++ = (q7_t) (__SSAT((((q15_t) *pSrc++ * scaleFract) >> kShift), 8)); |
| *pDst++ = (q7_t) (__SSAT((((q15_t) *pSrc++ * scaleFract) >> kShift), 8)); |
| *pDst++ = (q7_t) (__SSAT((((q15_t) *pSrc++ * scaleFract) >> kShift), 8)); |
| *pDst++ = (q7_t) (__SSAT((((q15_t) *pSrc++ * scaleFract) >> kShift), 8)); |
| #endif |
| |
| /* 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 = A * scale */ |
| |
| /* Scale input and store result in destination buffer. */ |
| *pDst++ = (q7_t) (__SSAT((((q15_t) *pSrc++ * scaleFract) >> kShift), 8)); |
| |
| /* Decrement loop counter */ |
| blkCnt--; |
| } |
| |
| } |
| |
| /** |
| @} end of BasicScale group |
| */ |