arm_mult_q7.c

00001 /* ----------------------------------------------------------------------  
00002 * Copyright (C) 2010 ARM Limited. All rights reserved.  
00003 *  
00004 * $Date:        29. November 2010  
00005 * $Revision:    V1.0.3  
00006 *  
00007 * Project:      CMSIS DSP Library  
00008 * Title:        arm_mult_q7.c  
00009 *  
00010 * Description:  Q7 vector multiplication.  
00011 *  
00012 * Target Processor: Cortex-M4/Cortex-M3
00013 *  
00014 * Version 1.0.3 2010/11/29 
00015 *    Re-organized the CMSIS folders and updated documentation.  
00016 *   
00017 * Version 1.0.2 2010/11/11  
00018 *    Documentation updated.   
00019 *  
00020 * Version 1.0.1 2010/10/05   
00021 *    Production release and review comments incorporated.  
00022 *  
00023 * Version 1.0.0 2010/09/20   
00024 *    Production release and review comments incorporated.  
00025 *  
00026 * Version 0.0.7  2010/06/10   
00027 *    Misra-C changes done  
00028 *  
00029 * Version 0.0.5  2010/04/26   
00030 *    incorporated review comments and updated with latest CMSIS layer  
00031 *  
00032 * Version 0.0.3  2010/03/10 DP  
00033 *    Initial version  
00034 * -------------------------------------------------------------------- */ 
00035  
00036 #include "arm_math.h" 
00037  
00038 /**  
00039  * @ingroup groupMath  
00040  */ 
00041  
00042 /**  
00043  * @addtogroup BasicMult  
00044  * @{  
00045  */ 
00046  
00047 /**  
00048  * @brief           Q7 vector multiplication  
00049  * @param[in]       *pSrcA points to the first input vector  
00050  * @param[in]       *pSrcB points to the second input vector  
00051  * @param[out]      *pDst points to the output vector  
00052  * @param[in]       blockSize number of samples in each vector  
00053  * @return none.  
00054  *  
00055  * <b>Scaling and Overflow Behavior:</b>  
00056  * \par  
00057  * The function uses saturating arithmetic.  
00058  * Results outside of the allowable Q7 range [0x80 0x7F] will be saturated.  
00059  */ 
00060  
00061 void arm_mult_q7( 
00062   q7_t * pSrcA, 
00063   q7_t * pSrcB, 
00064   q7_t * pDst, 
00065   uint32_t blockSize) 
00066 { 
00067   uint32_t blkCnt;                               /* loop counters */ 
00068   q7_t out1, out2, out3, out4;                   /* Temporary variables to store the product */ 
00069  
00070   /* loop Unrolling */ 
00071   blkCnt = blockSize >> 2u; 
00072  
00073   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.  
00074    ** a second loop below computes the remaining 1 to 3 samples. */ 
00075   while(blkCnt > 0u) 
00076   { 
00077     /* C = A * B */ 
00078     /* Multiply the inputs and store the results in temporary variables */ 
00079     out1 = (q7_t) (((q15_t) (*pSrcA++) * (*pSrcB++)) >> 7); 
00080     out2 = (q7_t) (((q15_t) (*pSrcA++) * (*pSrcB++)) >> 7); 
00081     out3 = (q7_t) (((q15_t) (*pSrcA++) * (*pSrcB++)) >> 7); 
00082     out4 = (q7_t) (((q15_t) (*pSrcA++) * (*pSrcB++)) >> 7); 
00083  
00084     /* Store the results of 4 inputs in the destination buffer in single cycle by packing */ 
00085     *__SIMD32(pDst)++ = __PACKq7(out1, out2, out3, out4); 
00086  
00087     /* Decrement the blockSize loop counter */ 
00088     blkCnt--; 
00089   } 
00090  
00091   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.  
00092    ** No loop unrolling is used. */ 
00093   blkCnt = blockSize % 0x4u; 
00094  
00095   while(blkCnt > 0u) 
00096   { 
00097     /* C = A * B */ 
00098     /* Multiply the inputs and store the result in the destination buffer */ 
00099     *pDst++ = (q7_t) (((q15_t) (*pSrcA++) * (*pSrcB++)) >> 7); 
00100  
00101     /* Decrement the blockSize loop counter */ 
00102     blkCnt--; 
00103   } 
00104 } 
00105  
00106 /**  
00107  * @} end of BasicMult group  
00108  */