| /* ---------------------------------------------------------------------- |
| * Project: CMSIS DSP Library |
| * Title: arm_scale_q15.c |
| * Description: Multiplies a Q15 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 Q15 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 1.15 format. |
| These are multiplied to yield a 2.30 intermediate result and this is shifted with saturation to 1.15 format. |
| */ |
| |
| void arm_scale_q15( |
| const q15_t *pSrc, |
| q15_t scaleFract, |
| int8_t shift, |
| q15_t *pDst, |
| uint32_t blockSize) |
| { |
| uint32_t blkCnt; /* Loop counter */ |
| int8_t kShift = 15 - shift; /* Shift to apply after scaling */ |
| |
| #if defined (ARM_MATH_LOOPUNROLL) |
| #if defined (ARM_MATH_DSP) |
| q31_t inA1, inA2; |
| q31_t out1, out2, out3, out4; /* Temporary output variables */ |
| q15_t in1, in2, in3, in4; /* Temporary input variables */ |
| #endif |
| #endif |
| |
| #if defined (ARM_MATH_LOOPUNROLL) |
| |
| /* Loop unrolling: Compute 4 outputs at a time */ |
| blkCnt = blockSize >> 2U; |
| |
| while (blkCnt > 0U) |
| { |
| /* C = A * scale */ |
| |
| #if defined (ARM_MATH_DSP) |
| /* read 2 times 2 samples at a time from source */ |
| inA1 = read_q15x2_ia ((q15_t **) &pSrc); |
| inA2 = read_q15x2_ia ((q15_t **) &pSrc); |
| |
| /* Scale inputs and store result in temporary variables |
| * in single cycle by packing the outputs */ |
| out1 = (q31_t) ((q15_t) (inA1 >> 16) * scaleFract); |
| out2 = (q31_t) ((q15_t) (inA1 ) * scaleFract); |
| out3 = (q31_t) ((q15_t) (inA2 >> 16) * scaleFract); |
| out4 = (q31_t) ((q15_t) (inA2 ) * scaleFract); |
| |
| /* apply shifting */ |
| out1 = out1 >> kShift; |
| out2 = out2 >> kShift; |
| out3 = out3 >> kShift; |
| out4 = out4 >> kShift; |
| |
| /* saturate the output */ |
| in1 = (q15_t) (__SSAT(out1, 16)); |
| in2 = (q15_t) (__SSAT(out2, 16)); |
| in3 = (q15_t) (__SSAT(out3, 16)); |
| in4 = (q15_t) (__SSAT(out4, 16)); |
| |
| /* store result to destination */ |
| write_q15x2_ia (&pDst, __PKHBT(in2, in1, 16)); |
| write_q15x2_ia (&pDst, __PKHBT(in4, in3, 16)); |
| #else |
| *pDst++ = (q15_t) (__SSAT(((q31_t) *pSrc++ * scaleFract) >> kShift, 16)); |
| *pDst++ = (q15_t) (__SSAT(((q31_t) *pSrc++ * scaleFract) >> kShift, 16)); |
| *pDst++ = (q15_t) (__SSAT(((q31_t) *pSrc++ * scaleFract) >> kShift, 16)); |
| *pDst++ = (q15_t) (__SSAT(((q31_t) *pSrc++ * scaleFract) >> kShift, 16)); |
| #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++ = (q15_t) (__SSAT(((q31_t) *pSrc++ * scaleFract) >> kShift, 16)); |
| |
| /* Decrement loop counter */ |
| blkCnt--; |
| } |
| |
| } |
| |
| /** |
| @} end of BasicScale group |
| */ |