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Rev	Author	Line No.	Line
2	mjames	1	/* ----------------------------------------------------------------------
		2	* Copyright (C) 2010-2014 ARM Limited. All rights reserved.
		3	*
		4	* $Date: 19. March 2015
		5	* $Revision: V.1.4.5
		6	*
		7	* Project: CMSIS DSP Library
		8	* Title: arm_mat_sub_q15.c
		9	*
		10	* Description: Q15 Matrix subtraction
		11	*
		12	* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
		13	*
		14	* Redistribution and use in source and binary forms, with or without
		15	* modification, are permitted provided that the following conditions
		16	* are met:
		17	* - Redistributions of source code must retain the above copyright
		18	* notice, this list of conditions and the following disclaimer.
		19	* - Redistributions in binary form must reproduce the above copyright
		20	* notice, this list of conditions and the following disclaimer in
		21	* the documentation and/or other materials provided with the
		22	* distribution.
		23	* - Neither the name of ARM LIMITED nor the names of its contributors
		24	* may be used to endorse or promote products derived from this
		25	* software without specific prior written permission.
		26	*
		27	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
		28	* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
		29	* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
		30	* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
		31	* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
		32	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
		33	* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
		34	* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
		35	* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
		36	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
		37	* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
		38	* POSSIBILITY OF SUCH DAMAGE.
		39	* -------------------------------------------------------------------- */
		40
		41	#include "arm_math.h"
		42
		43	/**
		44	* @ingroup groupMatrix
		45	*/
		46
		47	/**
		48	* @addtogroup MatrixSub
		49	* @{
		50	*/
		51
		52	/**
		53	* @brief Q15 matrix subtraction.
		54	* @param[in] *pSrcA points to the first input matrix structure
		55	* @param[in] *pSrcB points to the second input matrix structure
		56	* @param[out] *pDst points to output matrix structure
		57	* @return The function returns either
		58	* <code>ARM_MATH_SIZE_MISMATCH</code> or <code>ARM_MATH_SUCCESS</code> based on the outcome of size checking.
		59	*
		60	* <b>Scaling and Overflow Behavior:</b>
		61	* \par
		62	* The function uses saturating arithmetic.
		63	* Results outside of the allowable Q15 range [0x8000 0x7FFF] will be saturated.
		64	*/
		65
		66	arm_status arm_mat_sub_q15(
		67	const arm_matrix_instance_q15 * pSrcA,
		68	const arm_matrix_instance_q15 * pSrcB,
		69	arm_matrix_instance_q15 * pDst)
		70	{
		71	q15_t pInA = pSrcA->pData; / input data matrix pointer A */
		72	q15_t pInB = pSrcB->pData; / input data matrix pointer B */
		73	q15_t pOut = pDst->pData; / output data matrix pointer */
		74	uint32_t numSamples; /* total number of elements in the matrix */
		75	uint32_t blkCnt; /* loop counters */
		76	arm_status status; /* status of matrix subtraction */
		77
		78
		79	#ifdef ARM_MATH_MATRIX_CHECK
		80
		81
		82	/* Check for matrix mismatch condition */
		83	if((pSrcA->numRows != pSrcB->numRows) \|\|
		84	(pSrcA->numCols != pSrcB->numCols) \|\|
		85	(pSrcA->numRows != pDst->numRows) \|\| (pSrcA->numCols != pDst->numCols))
		86	{
		87	/* Set status as ARM_MATH_SIZE_MISMATCH */
		88	status = ARM_MATH_SIZE_MISMATCH;
		89	}
		90	else
		91	#endif /* #ifdef ARM_MATH_MATRIX_CHECK */
		92
		93	{
		94	/* Total number of samples in the input matrix */
		95	numSamples = (uint32_t) pSrcA->numRows * pSrcA->numCols;
		96
		97	#ifndef ARM_MATH_CM0_FAMILY
		98
		99	/* Run the below code for Cortex-M4 and Cortex-M3 */
		100
		101	/* Apply loop unrolling */
		102	blkCnt = numSamples >> 2u;
		103
		104	/* First part of the processing with loop unrolling. Compute 4 outputs at a time.
		105	** a second loop below computes the remaining 1 to 3 samples. */
		106	while(blkCnt > 0u)
		107	{
		108	/* C(m,n) = A(m,n) - B(m,n) */
		109	/* Subtract, Saturate and then store the results in the destination buffer. */
		110	__SIMD32(pOut)++ = __QSUB16(__SIMD32(pInA)++, *__SIMD32(pInB)++);
		111	__SIMD32(pOut)++ = __QSUB16(__SIMD32(pInA)++, *__SIMD32(pInB)++);
		112
		113	/* Decrement the loop counter */
		114	blkCnt--;
		115	}
		116
		117	/* If the blockSize is not a multiple of 4, compute any remaining output samples here.
		118	** No loop unrolling is used. */
		119	blkCnt = numSamples % 0x4u;
		120
		121	while(blkCnt > 0u)
		122	{
		123	/* C(m,n) = A(m,n) - B(m,n) */
		124	/* Subtract and then store the results in the destination buffer. */
		125	pOut++ = (q15_t) __QSUB16(pInA++, *pInB++);
		126
		127	/* Decrement the loop counter */
		128	blkCnt--;
		129	}
		130
		131	#else
		132
		133	/* Run the below code for Cortex-M0 */
		134
		135	/* Initialize blkCnt with number of samples */
		136	blkCnt = numSamples;
		137
		138	while(blkCnt > 0u)
		139	{
		140	/* C(m,n) = A(m,n) - B(m,n) */
		141	/* Subtract and then store the results in the destination buffer. */
		142	pOut++ = (q15_t) __SSAT(((q31_t) pInA++ - *pInB++), 16);
		143
		144	/* Decrement the loop counter */
		145	blkCnt--;
		146	}
		147
		148	#endif /* #ifndef ARM_MATH_CM0_FAMILY */
		149
		150	/* Set status as ARM_MATH_SUCCESS */
		151	status = ARM_MATH_SUCCESS;
		152	}
		153
		154	/* Return to application */
		155	return (status);
		156	}
		157
		158	/**
		159	* @} end of MatrixSub group
		160	*/

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