arm_offset_q7.c

/* ----------------------------------------------------------------------    
* Copyright (C) 2010 ARM Limited. All rights reserved.    
*    
* $Date:        15. February 2012  
* $Revision: 	V1.1.0  
*    
* Project: 	    CMSIS DSP Library    
* Title:		arm_offset_q7.c    
*    
* Description:	Q7 vector offset.    
*    
* 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 offset    
 * @{    
 */

/**    
 * @brief  Adds a constant offset to a Q7 vector.    
 * @param[in]  *pSrc points to the input vector    
 * @param[in]  offset is the offset to be added    
 * @param[out]  *pDst points to the output vector    
 * @param[in]  blockSize number of samples in the vector    
 * @return none.    
 *    
 * <b>Scaling and Overflow Behavior:</b>    
 * \par    
 * The function uses saturating arithmetic.    
 * Results outside of the allowable Q7 range [0x80 0x7F] are saturated.    
 */

void arm_offset_q7(
  q7_t * pSrc,
  q7_t offset,
  q7_t * pDst,
  uint32_t blockSize)
{
  uint32_t blkCnt;                               /* loop counter */

#ifndef ARM_MATH_CM0

/* Run the below code for Cortex-M4 and Cortex-M3 */
  q31_t offset_packed;                           /* Offset packed to 32 bit */


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

  /* Offset is packed to 32 bit in order to use SIMD32 for addition */
  offset_packed = __PACKq7(offset, offset, offset, offset);

  /* 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 + offset */
    /* Add offset and then store the results in the destination bufferfor 4 samples at a time. */
    *__SIMD32(pDst)++ = __QADD8(*__SIMD32(pSrc)++, offset_packed);

    /* 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;

  while(blkCnt > 0u)
  {
    /* C = A + offset */
    /* Add offset and then store the result in the destination buffer. */
    *pDst++ = (q7_t) __SSAT(*pSrc++ + offset, 8);

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

#else

  /* Run the below code for Cortex-M0 */

  /* Initialize blkCnt with number of samples */
  blkCnt = blockSize;

  while(blkCnt > 0u)
  {
    /* C = A + offset */
    /* Add offset and then store the result in the destination buffer. */
    *pDst++ = (q7_t) __SSAT((q15_t) * pSrc++ + offset, 8);

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

#endif /* #ifndef ARM_MATH_CM0 */

}

/**    
 * @} end of offset group    
 */