arm_mult_q7.c

00001 /* ----------------------------------------------------------------------
00002  * Project:      CMSIS DSP Library
00003  * Title:        arm_mult_q7.c
00004  * Description:  Q7 vector multiplication
00005  *
00006  * $Date:        27. January 2017
00007  * $Revision:    V.1.5.1
00008  *
00009  * Target Processor: Cortex-M cores
00010  * -------------------------------------------------------------------- */
00011 /*
00012  * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved.
00013  *
00014  * SPDX-License-Identifier: Apache-2.0
00015  *
00016  * Licensed under the Apache License, Version 2.0 (the License); you may
00017  * not use this file except in compliance with the License.
00018  * You may obtain a copy of the License at
00019  *
00020  * www.apache.org/licenses/LICENSE-2.0
00021  *
00022  * Unless required by applicable law or agreed to in writing, software
00023  * distributed under the License is distributed on an AS IS BASIS, WITHOUT
00024  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00025  * See the License for the specific language governing permissions and
00026  * limitations under the License.
00027  */
00028 
00029 #include "arm_math.h"
00030 
00031 /**
00032  * @ingroup groupMath
00033  */
00034 
00035 /**
00036  * @addtogroup BasicMult
00037  * @{
00038  */
00039 
00040 /**
00041  * @brief           Q7 vector multiplication
00042  * @param[in]       *pSrcA points to the first input vector
00043  * @param[in]       *pSrcB points to the second input vector
00044  * @param[out]      *pDst points to the output vector
00045  * @param[in]       blockSize number of samples in each vector
00046  * @return none.
00047  *
00048  * <b>Scaling and Overflow Behavior:</b>
00049  * \par
00050  * The function uses saturating arithmetic.
00051  * Results outside of the allowable Q7 range [0x80 0x7F] will be saturated.
00052  */
00053 
00054 void arm_mult_q7(
00055   q7_t * pSrcA,
00056   q7_t * pSrcB,
00057   q7_t * pDst,
00058   uint32_t blockSize)
00059 {
00060   uint32_t blkCnt;                               /* loop counters */
00061 
00062 #if defined (ARM_MATH_DSP)
00063 
00064 /* Run the below code for Cortex-M4 and Cortex-M3 */
00065   q7_t out1, out2, out3, out4;                   /* Temporary variables to store the product */
00066 
00067   /* loop Unrolling */
00068   blkCnt = blockSize >> 2U;
00069 
00070   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
00071    ** a second loop below computes the remaining 1 to 3 samples. */
00072   while (blkCnt > 0U)
00073   {
00074     /* C = A * B */
00075     /* Multiply the inputs and store the results in temporary variables */
00076     out1 = (q7_t) __SSAT((((q15_t) (*pSrcA++) * (*pSrcB++)) >> 7), 8);
00077     out2 = (q7_t) __SSAT((((q15_t) (*pSrcA++) * (*pSrcB++)) >> 7), 8);
00078     out3 = (q7_t) __SSAT((((q15_t) (*pSrcA++) * (*pSrcB++)) >> 7), 8);
00079     out4 = (q7_t) __SSAT((((q15_t) (*pSrcA++) * (*pSrcB++)) >> 7), 8);
00080 
00081     /* Store the results of 4 inputs in the destination buffer in single cycle by packing */
00082     *__SIMD32(pDst)++ = __PACKq7(out1, out2, out3, out4);
00083 
00084     /* Decrement the blockSize loop counter */
00085     blkCnt--;
00086   }
00087 
00088   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
00089    ** No loop unrolling is used. */
00090   blkCnt = blockSize % 0x4U;
00091 
00092 #else
00093 
00094   /* Run the below code for Cortex-M0 */
00095 
00096   /* Initialize blkCnt with number of samples */
00097   blkCnt = blockSize;
00098 
00099 #endif /* #if defined (ARM_MATH_DSP) */
00100 
00101 
00102   while (blkCnt > 0U)
00103   {
00104     /* C = A * B */
00105     /* Multiply the inputs and store the result in the destination buffer */
00106     *pDst++ = (q7_t) __SSAT((((q15_t) (*pSrcA++) * (*pSrcB++)) >> 7), 8);
00107 
00108     /* Decrement the blockSize loop counter */
00109     blkCnt--;
00110   }
00111 }
00112 
00113 /**
00114  * @} end of BasicMult group
00115  */
00116