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/* ----------------------------------------------------------------------    
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* Copyright (C) 2010-2014 ARM Limited. All rights reserved.    
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*    
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* $Date:        19. March 2015
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* $Revision:    V.1.4.5
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*    
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* Project:          CMSIS DSP Library    
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* Title:            arm_mat_sub_q31.c    
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*    
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* Description:  Q31 matrix subtraction    
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*    
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* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
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*  
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*   - Redistributions of source code must retain the above copyright
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*     notice, this list of conditions and the following disclaimer.
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*   - Redistributions in binary form must reproduce the above copyright
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*     notice, this list of conditions and the following disclaimer in
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*     the documentation and/or other materials provided with the
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*     distribution.
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*   - Neither the name of ARM LIMITED nor the names of its contributors
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*     may be used to endorse or promote products derived from this
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*     software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.    
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* -------------------------------------------------------------------- */
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#include "arm_math.h"
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/**        
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 * @ingroup groupMatrix        
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 */
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/**        
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 * @addtogroup MatrixSub        
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 * @{        
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 */
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/**        
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 * @brief Q31 matrix subtraction.        
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 * @param[in]       *pSrcA points to the first input matrix structure        
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 * @param[in]       *pSrcB points to the second input matrix structure        
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 * @param[out]      *pDst points to output matrix structure        
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 * @return              The function returns either        
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 * <code>ARM_MATH_SIZE_MISMATCH</code> or <code>ARM_MATH_SUCCESS</code> based on the outcome of size checking.        
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 *        
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 * <b>Scaling and Overflow Behavior:</b>        
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 * \par        
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 * The function uses saturating arithmetic.        
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 * Results outside of the allowable Q31 range [0x80000000 0x7FFFFFFF] will be saturated.        
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 */
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arm_status arm_mat_sub_q31(
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  const arm_matrix_instance_q31 * pSrcA,
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  const arm_matrix_instance_q31 * pSrcB,
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  arm_matrix_instance_q31 * pDst)
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{
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  q31_t *pIn1 = pSrcA->pData;                    /* input data matrix pointer A */
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  q31_t *pIn2 = pSrcB->pData;                    /* input data matrix pointer B */
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  q31_t *pOut = pDst->pData;                     /* output data matrix pointer */
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  q31_t inA1, inB1;                              /* temporary variables */
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#ifndef ARM_MATH_CM0_FAMILY
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  q31_t inA2, inB2;                              /* temporary variables */
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  q31_t out1, out2;                              /* temporary variables */
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#endif //      #ifndef ARM_MATH_CM0_FAMILY
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  uint32_t numSamples;                           /* total number of elements in the matrix  */
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  uint32_t blkCnt;                               /* loop counters */
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  arm_status status;                             /* status of matrix subtraction */
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#ifdef ARM_MATH_MATRIX_CHECK
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  /* Check for matrix mismatch condition  */
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  if((pSrcA->numRows != pSrcB->numRows) ||
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     (pSrcA->numCols != pSrcB->numCols) ||
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     (pSrcA->numRows != pDst->numRows) || (pSrcA->numCols != pDst->numCols))
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  {
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    /* Set status as ARM_MATH_SIZE_MISMATCH */
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    status = ARM_MATH_SIZE_MISMATCH;
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  }
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  else
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#endif
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  {
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    /* Total number of samples in the input matrix */
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    numSamples = (uint32_t) pSrcA->numRows * pSrcA->numCols;
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#ifndef ARM_MATH_CM0_FAMILY
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    /* Run the below code for Cortex-M4 and Cortex-M3 */
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    /* Loop Unrolling */
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    blkCnt = numSamples >> 2u;
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    /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.    
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     ** a second loop below computes the remaining 1 to 3 samples. */
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    while(blkCnt > 0u)
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    {
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      /* C(m,n) = A(m,n) - B(m,n) */
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      /* Subtract, saturate and then store the results in the destination buffer. */
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      /* Read values from source A */
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      inA1 = pIn1[0];
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      /* Read values from source B */
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      inB1 = pIn2[0];
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      /* Read values from source A */
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      inA2 = pIn1[1];
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      /* Subtract and saturate */
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      out1 = __QSUB(inA1, inB1);
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      /* Read values from source B */
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      inB2 = pIn2[1];
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      /* Read values from source A */
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      inA1 = pIn1[2];
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      /* Subtract and saturate */
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      out2 = __QSUB(inA2, inB2);
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      /* Read values from source B */
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      inB1 = pIn2[2];
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      /* Store result in destination */
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      pOut[0] = out1;
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      pOut[1] = out2;
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      /* Read values from source A */
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      inA2 = pIn1[3];
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      /* Read values from source B */
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      inB2 = pIn2[3];
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      /* Subtract and saturate */
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      out1 = __QSUB(inA1, inB1);
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      /* Subtract and saturate */
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      out2 = __QSUB(inA2, inB2);
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      /* Store result in destination */
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      pOut[2] = out1;
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      pOut[3] = out2;
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      /* update pointers to process next samples */
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      pIn1 += 4u;
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      pIn2 += 4u;
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      pOut += 4u;
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      /* Decrement the loop counter */
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      blkCnt--;
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    }
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    /* If the numSamples is not a multiple of 4, compute any remaining output samples here.        
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     ** No loop unrolling is used. */
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    blkCnt = numSamples % 0x4u;
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#else
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    /* Run the below code for Cortex-M0 */
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    /* Initialize blkCnt with number of samples */
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    blkCnt = numSamples;
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#endif /* #ifndef ARM_MATH_CM0_FAMILY */
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    while(blkCnt > 0u)
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    {
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      /* C(m,n) = A(m,n) - B(m,n) */
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      /* Subtract, saturate and then store the results in the destination buffer. */
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      inA1 = *pIn1++;
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      inB1 = *pIn2++;
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      inA1 = __QSUB(inA1, inB1);
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      *pOut++ = inA1;
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      /* Decrement the loop counter */
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      blkCnt--;
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    }
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    /* Set status as ARM_MATH_SUCCESS */
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    status = ARM_MATH_SUCCESS;
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  }
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  /* Return to application */
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  return (status);
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}
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/**        
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 * @} end of MatrixSub group        
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 */