lib/main/CMSIS/DSP/Source/SupportFunctions/arm_float_to_q7.c

   1 /* ----------------------------------------------------------------------
   2  * Project:      CMSIS DSP Library
   3  * Title:        arm_float_to_q7.c
   4  * Description:  Converts the elements of the floating-point vector to Q7 vector
   5  *
   6  * $Date:        27. January 2017
   7  * $Revision:    V.1.5.1
   8  *
   9  * Target Processor: Cortex-M cores
  10  * -------------------------------------------------------------------- */
  11 /*
  12  * Copyright (C) 2010-2017 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 "arm_math.h"
  30
  31 /**
  32  * @ingroup groupSupport
  33  */
  34
  35 /**
  36  * @addtogroup float_to_x
  37  * @{
  38  */
  39
  40 /**
  41  * @brief Converts the elements of the floating-point vector to Q7 vector.
  42  * @param[in]       *pSrc points to the floating-point input vector
  43  * @param[out]      *pDst points to the Q7 output vector
  44  * @param[in]       blockSize length of the input vector
  45  * @return none.
  46  *
  47  *\par Description:
  48  * \par
  49  * The equation used for the conversion process is:
  50  * <pre>
  51  *      pDst[n] = (q7_t)(pSrc[n] * 128);   0 <= n < blockSize.
  52  * </pre>
  53  * \par Scaling and Overflow Behavior:
  54  * \par
  55  * The function uses saturating arithmetic.
  56  * Results outside of the allowable Q7 range [0x80 0x7F] will be saturated.
  57  * \note
  58  * In order to apply rounding, the library should be rebuilt with the ROUNDING macro
  59  * defined in the preprocessor section of project options.
  60  */
  61
  62
  63 void arm_float_to_q7(
  64   float32_t * pSrc,
  65   q7_t * pDst,
  66   uint32_t blockSize)
  67 {
  68   float32_t *pIn = pSrc;                         /* Src pointer */
  69   uint32_t blkCnt;                               /* loop counter */
  70
  71 #ifdef ARM_MATH_ROUNDING
  72
  73   float32_t in;
  74
  75 #endif /*      #ifdef ARM_MATH_ROUNDING        */
  76
  77 #if defined (ARM_MATH_DSP)
  78
  79   /* Run the below code for Cortex-M4 and Cortex-M3 */
  80
  81   /*loop Unrolling */
  82   blkCnt = blockSize >> 2U;
  83
  84   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
  85    ** a second loop below computes the remaining 1 to 3 samples. */
  86   while (blkCnt > 0U)
  87   {
  88
  89 #ifdef ARM_MATH_ROUNDING
  90     /* C = A * 128 */
  91     /* convert from float to q7 and then store the results in the destination buffer */
  92     in = *pIn++;
  93     in = (in * 128);
  94     in += in > 0.0f ? 0.5f : -0.5f;
  95     *pDst++ = (q7_t) (__SSAT((q15_t) (in), 8));
  96
  97     in = *pIn++;
  98     in = (in * 128);
  99     in += in > 0.0f ? 0.5f : -0.5f;
 100     *pDst++ = (q7_t) (__SSAT((q15_t) (in), 8));
 101
 102     in = *pIn++;
 103     in = (in * 128);
 104     in += in > 0.0f ? 0.5f : -0.5f;
 105     *pDst++ = (q7_t) (__SSAT((q15_t) (in), 8));
 106
 107     in = *pIn++;
 108     in = (in * 128);
 109     in += in > 0.0f ? 0.5f : -0.5f;
 110     *pDst++ = (q7_t) (__SSAT((q15_t) (in), 8));
 111
 112 #else
 113
 114     /* C = A * 128 */
 115     /* convert from float to q7 and then store the results in the destination buffer */
 116     *pDst++ = __SSAT((q31_t) (*pIn++ * 128.0f), 8);
 117     *pDst++ = __SSAT((q31_t) (*pIn++ * 128.0f), 8);
 118     *pDst++ = __SSAT((q31_t) (*pIn++ * 128.0f), 8);
 119     *pDst++ = __SSAT((q31_t) (*pIn++ * 128.0f), 8);
 120
 121 #endif /*      #ifdef ARM_MATH_ROUNDING        */
 122
 123     /* Decrement the loop counter */
 124     blkCnt--;
 125   }
 126
 127   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
 128    ** No loop unrolling is used. */
 129   blkCnt = blockSize % 0x4U;
 130
 131   while (blkCnt > 0U)
 132   {
 133
 134 #ifdef ARM_MATH_ROUNDING
 135     /* C = A * 128 */
 136     /* convert from float to q7 and then store the results in the destination buffer */
 137     in = *pIn++;
 138     in = (in * 128);
 139     in += in > 0.0f ? 0.5f : -0.5f;
 140     *pDst++ = (q7_t) (__SSAT((q15_t) (in), 8));
 141
 142 #else
 143
 144     /* C = A * 128 */
 145     /* convert from float to q7 and then store the results in the destination buffer */
 146     *pDst++ = __SSAT((q31_t) (*pIn++ * 128.0f), 8);
 147
 148 #endif /*      #ifdef ARM_MATH_ROUNDING        */
 149
 150     /* Decrement the loop counter */
 151     blkCnt--;
 152   }
 153
 154
 155 #else
 156
 157   /* Run the below code for Cortex-M0 */
 158
 159
 160   /* Loop over blockSize number of values */
 161   blkCnt = blockSize;
 162
 163   while (blkCnt > 0U)
 164   {
 165 #ifdef ARM_MATH_ROUNDING
 166     /* C = A * 128 */
 167     /* convert from float to q7 and then store the results in the destination buffer */
 168     in = *pIn++;
 169     in = (in * 128.0f);
 170     in += in > 0 ? 0.5f : -0.5f;
 171     *pDst++ = (q7_t) (__SSAT((q31_t) (in), 8));
 172
 173 #else
 174
 175     /* C = A * 128 */
 176     /* convert from float to q7 and then store the results in the destination buffer */
 177     *pDst++ = (q7_t) __SSAT((q31_t) (*pIn++ * 128.0f), 8);
 178
 179 #endif /*      #ifdef ARM_MATH_ROUNDING        */
 180
 181     /* Decrement the loop counter */
 182     blkCnt--;
 183   }
 184
 185 #endif /* #if defined (ARM_MATH_DSP) */
 186
 187 }
 188
 189 /**
 190  * @} end of float_to_x group
 191  */