| /* ---------------------------------------------------------------------- |
| * Project: CMSIS DSP Library |
| * Title: arm_scale_f32.c |
| * Description: Multiplies a floating-point 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 |
| */ |
| |
| /** |
| @defgroup BasicScale Vector Scale |
| |
| Multiply a vector by a scalar value. For floating-point data, the algorithm used is: |
| |
| <pre> |
| pDst[n] = pSrc[n] * scale, 0 <= n < blockSize. |
| </pre> |
| |
| In the fixed-point Q7, Q15, and Q31 functions, <code>scale</code> is represented by |
| a fractional multiplication <code>scaleFract</code> and an arithmetic shift <code>shift</code>. |
| The shift allows the gain of the scaling operation to exceed 1.0. |
| The algorithm used with fixed-point data is: |
| |
| <pre> |
| pDst[n] = (pSrc[n] * scaleFract) << shift, 0 <= n < blockSize. |
| </pre> |
| |
| The overall scale factor applied to the fixed-point data is |
| <pre> |
| scale = scaleFract * 2^shift. |
| </pre> |
| |
| The functions support in-place computation allowing the source and destination |
| pointers to reference the same memory buffer. |
| */ |
| |
| /** |
| @addtogroup BasicScale |
| @{ |
| */ |
| |
| /** |
| @brief Multiplies a floating-point vector by a scalar. |
| @param[in] pSrc points to the input vector |
| @param[in] scale scale factor to be applied |
| @param[out] pDst points to the output vector |
| @param[in] blockSize number of samples in each vector |
| @return none |
| */ |
| |
| void arm_scale_f32( |
| const float32_t *pSrc, |
| float32_t scale, |
| float32_t *pDst, |
| uint32_t blockSize) |
| { |
| uint32_t blkCnt; /* Loop counter */ |
| #if defined(ARM_MATH_NEON_EXPERIMENTAL) |
| float32x4_t vec1; |
| float32x4_t res; |
| |
| /* Compute 4 outputs at a time */ |
| blkCnt = blockSize >> 2U; |
| |
| while (blkCnt > 0U) |
| { |
| /* C = A * scale */ |
| |
| /* Scale the input and then store the results in the destination buffer. */ |
| vec1 = vld1q_f32(pSrc); |
| res = vmulq_f32(vec1, vdupq_n_f32(scale)); |
| vst1q_f32(pDst, res); |
| |
| /* Increment pointers */ |
| pSrc += 4; |
| pDst += 4; |
| |
| /* Decrement the loop counter */ |
| blkCnt--; |
| } |
| |
| /* Tail */ |
| blkCnt = blockSize & 0x3; |
| |
| #else |
| #if defined (ARM_MATH_LOOPUNROLL) |
| |
| /* Loop unrolling: Compute 4 outputs at a time */ |
| blkCnt = blockSize >> 2U; |
| |
| while (blkCnt > 0U) |
| { |
| /* C = A * scale */ |
| |
| /* Scale input and store result in destination buffer. */ |
| *pDst++ = (*pSrc++) * scale; |
| |
| *pDst++ = (*pSrc++) * scale; |
| |
| *pDst++ = (*pSrc++) * scale; |
| |
| *pDst++ = (*pSrc++) * scale; |
| |
| /* 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) */ |
| #endif /* #if defined(ARM_MATH_NEON_EXPERIMENTAL) */ |
| |
| while (blkCnt > 0U) |
| { |
| /* C = A * scale */ |
| |
| /* Scale input and store result in destination buffer. */ |
| *pDst++ = (*pSrc++) * scale; |
| |
| /* Decrement loop counter */ |
| blkCnt--; |
| } |
| |
| } |
| |
| /** |
| @} end of BasicScale group |
| */ |