File content as of revision 1:fdd22bb7aa52:

/* ----------------------------------------------------------------------    
* Copyright (C) 2010 ARM Limited. All rights reserved.    
*    
* $Date:        15. February 2012  
* $Revision:     V1.1.0  
*    
* Project:         CMSIS DSP Library    
* Title:        arm_abs_q7.c    
*    
* Description:    Q7 vector absolute value.    
*    
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*  
* Version 1.1.0 2012/02/15 
*    Updated with more optimizations, bug fixes and minor API changes.  
*   
* Version 1.0.10 2011/7/15  
*    Big Endian support added and Merged M0 and M3/M4 Source code.   
*    
* Version 1.0.3 2010/11/29   
*    Re-organized the CMSIS folders and updated documentation.    
*     
* Version 1.0.2 2010/11/11    
*    Documentation updated.     
*    
* Version 1.0.1 2010/10/05     
*    Production release and review comments incorporated.    
*    
* Version 1.0.0 2010/09/20     
*    Production release and review comments incorporated.    
*    
* Version 0.0.7  2010/06/10     
*    Misra-C changes done    
* -------------------------------------------------------------------- */

#include "arm_math.h"

/**        
 * @ingroup groupMath        
 */

/**        
 * @addtogroup BasicAbs        
 * @{        
 */

/**        
 * @brief Q7 vector absolute value.        
 * @param[in]       *pSrc points to the input buffer        
 * @param[out]      *pDst points to the output buffer        
 * @param[in]       blockSize number of samples in each vector        
 * @return none.        
 *    
 * \par Conditions for optimum performance    
 *  Input and output buffers should be aligned by 32-bit    
 *    
 *        
 * <b>Scaling and Overflow Behavior:</b>        
 * \par        
 * The function uses saturating arithmetic.        
 * The Q7 value -1 (0x80) will be saturated to the maximum allowable positive value 0x7F.        
 */

void arm_abs_q7(
  q7_t * pSrc,
  q7_t * pDst,
  uint32_t blockSize)
{
  uint32_t blkCnt;                               /* loop counter */
  q7_t in;                                       /* Input value1 */

#ifndef ARM_MATH_CM0

  /* Run the below code for Cortex-M4 and Cortex-M3 */
  q31_t in1, in2, in3, in4;                      /* temporary input variables */
  q31_t out1, out2, out3, out4;                  /* temporary output variables */

  /*loop Unrolling */
  blkCnt = blockSize >> 2u;

  /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.    
   ** a second loop below computes the remaining 1 to 3 samples. */
  while(blkCnt > 0u)
  {
    /* C = |A| */
    /* Read inputs */
    in1 = (q31_t) * pSrc;
    in2 = (q31_t) * (pSrc + 1);
    in3 = (q31_t) * (pSrc + 2);

    /* find absolute value */
    out1 = (in1 > 0) ? in1 : __QSUB8(0, in1);

    /* read input */
    in4 = (q31_t) * (pSrc + 3);

    /* find absolute value */
    out2 = (in2 > 0) ? in2 : __QSUB8(0, in2);

    /* store result to destination */
    *pDst = (q7_t) out1;

    /* find absolute value */
    out3 = (in3 > 0) ? in3 : __QSUB8(0, in3);

    /* find absolute value */
    out4 = (in4 > 0) ? in4 : __QSUB8(0, in4);

    /* store result to destination */
    *(pDst + 1) = (q7_t) out2;

    /* store result to destination */
    *(pDst + 2) = (q7_t) out3;

    /* store result to destination */
    *(pDst + 3) = (q7_t) out4;

    /* update pointers to process next samples */
    pSrc += 4u;
    pDst += 4u;

    /* Decrement the loop counter */
    blkCnt--;
  }

  /* If the blockSize is not a multiple of 4, compute any remaining output samples here.    
   ** No loop unrolling is used. */
  blkCnt = blockSize % 0x4u;
#else

  /* Run the below code for Cortex-M0 */
  blkCnt = blockSize;

#endif //      #define ARM_MATH_CM0

  while(blkCnt > 0u)
  {
    /* C = |A| */
    /* Read the input */
    in = *pSrc++;

    /* Store the Absolute result in the destination buffer */
    *pDst++ = (in > 0) ? in : ((in == (q7_t) 0x80) ? 0x7f : -in);

    /* Decrement the loop counter */
    blkCnt--;
  }
}

/**        
 * @} end of BasicAbs group        
 */