tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/BasicMathFunctions/arm_shift_q7.c

   1 /* ----------------------------------------------------------------------
   2 * Copyright (C) 2010-2013 ARM Limited. All rights reserved.
   3 *
   4 * $Date:        17. January 2013
   5 * $Revision:    V1.4.1
   6 *
   7 * Project:          CMSIS DSP Library
   8 * Title:                arm_shift_q7.c
   9 *
  10 * Description:  Processing function for the Q7 Shifting
  11 *
  12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
  13 *
  14 * Redistribution and use in source and binary forms, with or without
  15 * modification, are permitted provided that the following conditions
  16 * are met:
  17 *   - Redistributions of source code must retain the above copyright
  18 *     notice, this list of conditions and the following disclaimer.
  19 *   - Redistributions in binary form must reproduce the above copyright
  20 *     notice, this list of conditions and the following disclaimer in
  21 *     the documentation and/or other materials provided with the
  22 *     distribution.
  23 *   - Neither the name of ARM LIMITED nor the names of its contributors
  24 *     may be used to endorse or promote products derived from this
  25 *     software without specific prior written permission.
  26 *
  27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  30 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  31 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  33 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  34 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  37 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  38 * POSSIBILITY OF SUCH DAMAGE.
  39 * -------------------------------------------------------------------- */
  40
  41 #include "arm_math.h"
  42
  43 /**
  44  * @ingroup groupMath
  45  */
  46
  47 /**
  48  * @addtogroup shift
  49  * @{
  50  */
  51
  52
  53 /**
  54  * @brief  Shifts the elements of a Q7 vector a specified number of bits.
  55  * @param[in]  *pSrc points to the input vector
  56  * @param[in]  shiftBits number of bits to shift.  A positive value shifts left; a negative value shifts right.
  57  * @param[out]  *pDst points to the output vector
  58  * @param[in]  blockSize number of samples in the vector
  59  * @return none.
  60  *
  61  * \par Conditions for optimum performance
  62  *  Input and output buffers should be aligned by 32-bit
  63  *
  64  *
  65  * <b>Scaling and Overflow Behavior:</b>
  66  * \par
  67  * The function uses saturating arithmetic.
  68  * Results outside of the allowable Q7 range [0x8 0x7F] will be saturated.
  69  */
  70
  71 void arm_shift_q7(
  72   q7_t * pSrc,
  73   int8_t shiftBits,
  74   q7_t * pDst,
  75   uint32_t blockSize)
  76 {
  77   uint32_t blkCnt;                               /* loop counter */
  78   uint8_t sign;                                  /* Sign of shiftBits */
  79
  80 #ifndef ARM_MATH_CM0_FAMILY
  81
  82 /* Run the below code for Cortex-M4 and Cortex-M3 */
  83   q7_t in1;                                      /* Input value1 */
  84   q7_t in2;                                      /* Input value2 */
  85   q7_t in3;                                      /* Input value3 */
  86   q7_t in4;                                      /* Input value4 */
  87
  88
  89   /*loop Unrolling */
  90   blkCnt = blockSize >> 2u;
  91
  92   /* Getting the sign of shiftBits */
  93   sign = (shiftBits & 0x80);
  94
  95   /* If the shift value is positive then do right shift else left shift */
  96   if(sign == 0u)
  97   {
  98     /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
  99      ** a second loop below computes the remaining 1 to 3 samples. */
 100     while(blkCnt > 0u)
 101     {
 102       /* C = A << shiftBits */
 103       /* Read 4 inputs */
 104       in1 = *pSrc;
 105       in2 = *(pSrc + 1);
 106       in3 = *(pSrc + 2);
 107       in4 = *(pSrc + 3);
 108
 109       /* Store the Shifted result in the destination buffer in single cycle by packing the outputs */
 110       *__SIMD32(pDst)++ = __PACKq7(__SSAT((in1 << shiftBits), 8),
 111                                    __SSAT((in2 << shiftBits), 8),
 112                                    __SSAT((in3 << shiftBits), 8),
 113                                    __SSAT((in4 << shiftBits), 8));
 114       /* Update source pointer to process next sampels */
 115       pSrc += 4u;
 116
 117       /* Decrement the loop counter */
 118       blkCnt--;
 119     }
 120
 121     /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
 122      ** No loop unrolling is used. */
 123     blkCnt = blockSize % 0x4u;
 124
 125     while(blkCnt > 0u)
 126     {
 127       /* C = A << shiftBits */
 128       /* Shift the input and then store the result in the destination buffer. */
 129       *pDst++ = (q7_t) __SSAT((*pSrc++ << shiftBits), 8);
 130
 131       /* Decrement the loop counter */
 132       blkCnt--;
 133     }
 134   }
 135   else
 136   {
 137     shiftBits = -shiftBits;
 138     /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
 139      ** a second loop below computes the remaining 1 to 3 samples. */
 140     while(blkCnt > 0u)
 141     {
 142       /* C = A >> shiftBits */
 143       /* Read 4 inputs */
 144       in1 = *pSrc;
 145       in2 = *(pSrc + 1);
 146       in3 = *(pSrc + 2);
 147       in4 = *(pSrc + 3);
 148
 149       /* Store the Shifted result in the destination buffer in single cycle by packing the outputs */
 150       *__SIMD32(pDst)++ = __PACKq7((in1 >> shiftBits), (in2 >> shiftBits),
 151                                    (in3 >> shiftBits), (in4 >> shiftBits));
 152
 153
 154       pSrc += 4u;
 155
 156       /* Decrement the loop counter */
 157       blkCnt--;
 158     }
 159
 160     /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
 161      ** No loop unrolling is used. */
 162     blkCnt = blockSize % 0x4u;
 163
 164     while(blkCnt > 0u)
 165     {
 166       /* C = A >> shiftBits */
 167       /* Shift the input and then store the result in the destination buffer. */
 168       in1 = *pSrc++;
 169       *pDst++ = (in1 >> shiftBits);
 170
 171       /* Decrement the loop counter */
 172       blkCnt--;
 173     }
 174   }
 175
 176 #else
 177
 178   /* Run the below code for Cortex-M0 */
 179
 180   /* Getting the sign of shiftBits */
 181   sign = (shiftBits & 0x80);
 182
 183   /* If the shift value is positive then do right shift else left shift */
 184   if(sign == 0u)
 185   {
 186     /* Initialize blkCnt with number of samples */
 187     blkCnt = blockSize;
 188
 189     while(blkCnt > 0u)
 190     {
 191       /* C = A << shiftBits */
 192       /* Shift the input and then store the result in the destination buffer. */
 193       *pDst++ = (q7_t) __SSAT(((q15_t) * pSrc++ << shiftBits), 8);
 194
 195       /* Decrement the loop counter */
 196       blkCnt--;
 197     }
 198   }
 199   else
 200   {
 201     /* Initialize blkCnt with number of samples */
 202     blkCnt = blockSize;
 203
 204     while(blkCnt > 0u)
 205     {
 206       /* C = A >> shiftBits */
 207       /* Shift the input and then store the result in the destination buffer. */
 208       *pDst++ = (*pSrc++ >> -shiftBits);
 209
 210       /* Decrement the loop counter */
 211       blkCnt--;
 212     }
 213   }
 214
 215 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
 216 }
 217
 218 /**
 219  * @} end of shift group
 220  */