1  /* ----------------------------------------------------------------------
  2   * Project:      CMSIS DSP Library
  3   * Title:        arm_scale_q7.c
  4   * Description:  Multiplies a Q7 vector by a scalar
  5   *
  6   * $Date:        23 April 2021
  7   * $Revision:    V1.9.0
  8   *
  9   * Target Processor: Cortex-M and Cortex-A cores
 10   * -------------------------------------------------------------------- */
 11  /*
 12   * Copyright (C) 2010-2021 ARM Limited or its affiliates. All rights reserved.
 13   *
 14   * SPDX-License-Identifier: Apache-2.0
 15   *
 16   * Licensed under the Apache License, Version 2.0 (the License); you may
 17   * not use this file except in compliance with the License.
 18   * You may obtain a copy of the License at
 19   *
 20   * www.apache.org/licenses/LICENSE-2.0
 21   *
 22   * Unless required by applicable law or agreed to in writing, software
 23   * distributed under the License is distributed on an AS IS BASIS, WITHOUT
 24   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 25   * See the License for the specific language governing permissions and
 26   * limitations under the License.
 27   */
 28  
 29  #include "dsp/basic_math_functions.h"
 30  
 31  /**
 32    @ingroup groupMath
 33   */
 34  
 35  /**
 36    @addtogroup BasicScale
 37    @{
 38   */
 39  
 40  /**
 41    @brief         Multiplies a Q7 vector by a scalar.
 42    @param[in]     pSrc       points to the input vector
 43    @param[in]     scaleFract fractional portion of the scale value
 44    @param[in]     shift      number of bits to shift the result by
 45    @param[out]    pDst       points to the output vector
 46    @param[in]     blockSize  number of samples in each vector
 47    @return        none
 48  
 49    @par           Scaling and Overflow Behavior
 50                     The input data <code>*pSrc</code> and <code>scaleFract</code> are in 1.7 format.
 51                     These are multiplied to yield a 2.14 intermediate result and this is shifted with saturation to 1.7 format.
 52   */
 53  
 54  #if defined(ARM_MATH_MVEI) && !defined(ARM_MATH_AUTOVECTORIZE)
 55  
 56  #include "arm_helium_utils.h"
 57  
 58  
 59  void arm_scale_q7(
 60      const q7_t * pSrc,
 61      q7_t   scaleFract,
 62      int8_t  shift,
 63      q7_t * pDst,
 64      uint32_t blockSize)
 65  {
 66      uint32_t  blkCnt;           /* loop counters */
 67      q7x16_t vecSrc;
 68      q7x16_t vecDst;
 69  
 70  
 71      /* Compute 16 outputs at a time */
 72      blkCnt = blockSize >> 4;
 73  
 74      while (blkCnt > 0U)
 75      {
 76          /*
 77           * C = A * scale
 78           * Scale the input and then store the result in the destination buffer.
 79           */
 80          vecSrc = vld1q(pSrc);
 81          vecDst = vmulhq(vecSrc, vdupq_n_s8(scaleFract));
 82          vecDst = vqshlq_r(vecDst, shift + 1);
 83          vst1q(pDst, vecDst);
 84          /*
 85           * Decrement the blockSize loop counter
 86           */
 87          blkCnt--;
 88          /*
 89           * advance vector source and destination pointers
 90           */
 91          pSrc += 16;
 92          pDst += 16;
 93      }
 94      /*
 95       * tail
 96       */
 97      blkCnt = blockSize & 0xF;
 98      if (blkCnt > 0U)
 99      {
100          mve_pred16_t p0 = vctp8q(blkCnt);
101          vecSrc = vld1q(pSrc);
102          vecDst = vmulhq(vecSrc, vdupq_n_s8(scaleFract));
103          vecDst = vqshlq_r(vecDst, shift + 1);
104          vstrbq_p(pDst, vecDst, p0);
105      }
106  
107  }
108  
109  #else
110  void arm_scale_q7(
111    const q7_t * pSrc,
112          q7_t scaleFract,
113          int8_t shift,
114          q7_t * pDst,
115          uint32_t blockSize)
116  {
117          uint32_t blkCnt;                               /* Loop counter */
118          int8_t kShift = 7 - shift;                     /* Shift to apply after scaling */
119  
120  #if defined (ARM_MATH_LOOPUNROLL)
121  
122  #if defined (ARM_MATH_DSP)
123    q7_t in1,  in2,  in3,  in4;                    /* Temporary input variables */
124    q7_t out1, out2, out3, out4;                   /* Temporary output variables */
125  #endif
126  
127    /* Loop unrolling: Compute 4 outputs at a time */
128    blkCnt = blockSize >> 2U;
129  
130    while (blkCnt > 0U)
131    {
132      /* C = A * scale */
133  
134  #if defined (ARM_MATH_DSP)
135      /* Reading 4 inputs from memory */
136      in1 = *pSrc++;
137      in2 = *pSrc++;
138      in3 = *pSrc++;
139      in4 = *pSrc++;
140  
141      /* Scale inputs and store result in the temporary variable. */
142      out1 = (q7_t) (__SSAT(((in1) * scaleFract) >> kShift, 8));
143      out2 = (q7_t) (__SSAT(((in2) * scaleFract) >> kShift, 8));
144      out3 = (q7_t) (__SSAT(((in3) * scaleFract) >> kShift, 8));
145      out4 = (q7_t) (__SSAT(((in4) * scaleFract) >> kShift, 8));
146  
147      /* Pack and store result in destination buffer (in single write) */
148      write_q7x4_ia (&pDst, __PACKq7(out1, out2, out3, out4));
149  #else
150      *pDst++ = (q7_t) (__SSAT((((q15_t) *pSrc++ * scaleFract) >> kShift), 8));
151      *pDst++ = (q7_t) (__SSAT((((q15_t) *pSrc++ * scaleFract) >> kShift), 8));
152      *pDst++ = (q7_t) (__SSAT((((q15_t) *pSrc++ * scaleFract) >> kShift), 8));
153      *pDst++ = (q7_t) (__SSAT((((q15_t) *pSrc++ * scaleFract) >> kShift), 8));
154  #endif
155  
156      /* Decrement loop counter */
157      blkCnt--;
158    }
159  
160    /* Loop unrolling: Compute remaining outputs */
161    blkCnt = blockSize % 0x4U;
162  
163  #else
164  
165    /* Initialize blkCnt with number of samples */
166    blkCnt = blockSize;
167  
168  #endif /* #if defined (ARM_MATH_LOOPUNROLL) */
169  
170    while (blkCnt > 0U)
171    {
172      /* C = A * scale */
173  
174      /* Scale input and store result in destination buffer. */
175      *pDst++ = (q7_t) (__SSAT((((q15_t) *pSrc++ * scaleFract) >> kShift), 8));
176  
177      /* Decrement loop counter */
178      blkCnt--;
179    }
180  
181  }
182  #endif /* defined(ARM_MATH_MVEI) */
183  
184  /**
185    @} end of BasicScale group
186   */