| /* ---------------------------------------------------------------------- |
| * Project: CMSIS DSP Library |
| * Title: arm_scale_q31.c |
| * Description: Multiplies a Q31 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 Q31 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 1.31 format. |
| These are multiplied to yield a 2.62 intermediate result and this is shifted with saturation to 1.31 format. |
| */ |
| |
| void arm_scale_q31( |
| const q31_t *pSrc, |
| q31_t scaleFract, |
| int8_t shift, |
| q31_t *pDst, |
| uint32_t blockSize) |
| { |
| uint32_t blkCnt; /* Loop counter */ |
| q31_t in, out; /* Temporary variables */ |
| int8_t kShift = shift + 1; /* Shift to apply after scaling */ |
| int8_t sign = (kShift & 0x80); |
| |
| #if defined (ARM_MATH_LOOPUNROLL) |
| |
| /* Loop unrolling: Compute 4 outputs at a time */ |
| blkCnt = blockSize >> 2U; |
| |
| if (sign == 0U) |
| { |
| while (blkCnt > 0U) |
| { |
| /* C = A * scale */ |
| |
| /* Scale input and store result in destination buffer. */ |
| in = *pSrc++; /* read input from source */ |
| in = ((q63_t) in * scaleFract) >> 32; /* multiply input with scaler value */ |
| out = in << kShift; /* apply shifting */ |
| if (in != (out >> kShift)) /* saturate the result */ |
| out = 0x7FFFFFFF ^ (in >> 31); |
| *pDst++ = out; /* Store result destination */ |
| |
| in = *pSrc++; |
| in = ((q63_t) in * scaleFract) >> 32; |
| out = in << kShift; |
| if (in != (out >> kShift)) |
| out = 0x7FFFFFFF ^ (in >> 31); |
| *pDst++ = out; |
| |
| in = *pSrc++; |
| in = ((q63_t) in * scaleFract) >> 32; |
| out = in << kShift; |
| if (in != (out >> kShift)) |
| out = 0x7FFFFFFF ^ (in >> 31); |
| *pDst++ = out; |
| |
| in = *pSrc++; |
| in = ((q63_t) in * scaleFract) >> 32; |
| out = in << kShift; |
| if (in != (out >> kShift)) |
| out = 0x7FFFFFFF ^ (in >> 31); |
| *pDst++ = out; |
| |
| /* Decrement loop counter */ |
| blkCnt--; |
| } |
| } |
| else |
| { |
| while (blkCnt > 0U) |
| { |
| /* C = A * scale */ |
| |
| /* Scale input and store result in destination buffer. */ |
| in = *pSrc++; /* read four inputs from source */ |
| in = ((q63_t) in * scaleFract) >> 32; /* multiply input with scaler value */ |
| out = in >> -kShift; /* apply shifting */ |
| *pDst++ = out; /* Store result destination */ |
| |
| in = *pSrc++; |
| in = ((q63_t) in * scaleFract) >> 32; |
| out = in >> -kShift; |
| *pDst++ = out; |
| |
| in = *pSrc++; |
| in = ((q63_t) in * scaleFract) >> 32; |
| out = in >> -kShift; |
| *pDst++ = out; |
| |
| in = *pSrc++; |
| in = ((q63_t) in * scaleFract) >> 32; |
| out = in >> -kShift; |
| *pDst++ = out; |
| |
| /* 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) */ |
| |
| if (sign == 0U) |
| { |
| while (blkCnt > 0U) |
| { |
| /* C = A * scale */ |
| |
| /* Scale input and store result in destination buffer. */ |
| in = *pSrc++; |
| in = ((q63_t) in * scaleFract) >> 32; |
| out = in << kShift; |
| if (in != (out >> kShift)) |
| out = 0x7FFFFFFF ^ (in >> 31); |
| *pDst++ = out; |
| |
| /* Decrement loop counter */ |
| blkCnt--; |
| } |
| } |
| else |
| { |
| while (blkCnt > 0U) |
| { |
| /* C = A * scale */ |
| |
| /* Scale input and store result in destination buffer. */ |
| in = *pSrc++; |
| in = ((q63_t) in * scaleFract) >> 32; |
| out = in >> -kShift; |
| *pDst++ = out; |
| |
| /* Decrement loop counter */ |
| blkCnt--; |
| } |
| } |
| |
| } |
| |
| /** |
| @} end of BasicScale group |
| */ |