arm_min_q31.c

00001 /* ----------------------------------------------------------------------
00002  * Project:      CMSIS DSP Library
00003  * Title:        arm_min_q31.c
00004  * Description:  Minimum value of a Q31 vector
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 groupStats
00033  */
00034 
00035 
00036 /**
00037  * @addtogroup Min
00038  * @{
00039  */
00040 
00041 
00042 /**
00043  * @brief Minimum value of a Q31 vector.
00044  * @param[in]       *pSrc points to the input vector
00045  * @param[in]       blockSize length of the input vector
00046  * @param[out]      *pResult minimum value returned here
00047  * @param[out]      *pIndex index of minimum value returned here
00048  * @return none.
00049  */
00050 
00051 void arm_min_q31(
00052   q31_t * pSrc,
00053   uint32_t blockSize,
00054   q31_t * pResult,
00055   uint32_t * pIndex)
00056 {
00057 #if defined (ARM_MATH_DSP)
00058   /* Run the below code for Cortex-M4 and Cortex-M3 */
00059 
00060   q31_t minVal1, minVal2, out;                   /* Temporary variables to store the output value. */
00061   uint32_t blkCnt, outIndex, count;              /* loop counter */
00062 
00063   /* Initialise the count value. */
00064   count = 0U;
00065   /* Initialise the index value to zero. */
00066   outIndex = 0U;
00067   /* Load first input value that act as reference value for comparision */
00068   out = *pSrc++;
00069 
00070   /* Loop unrolling */
00071   blkCnt = (blockSize - 1U) >> 2U;
00072 
00073   while (blkCnt > 0U)
00074   {
00075     /* Initialize minVal to the next consecutive values one by one */
00076     minVal1 = *pSrc++;
00077     minVal2 = *pSrc++;
00078 
00079     /* compare for the minimum value */
00080     if (out > minVal1)
00081     {
00082       /* Update the minimum value and its index */
00083       out = minVal1;
00084       outIndex = count + 1U;
00085     }
00086 
00087     /* compare for the minimum value */
00088     if (out > minVal2)
00089     {
00090       /* Update the minimum value and its index */
00091       out = minVal2;
00092       outIndex = count + 2U;
00093     }
00094 
00095     /* Initialize minVal to the next consecutive values one by one */
00096     minVal1 = *pSrc++;
00097     minVal2 = *pSrc++;
00098 
00099     /* compare for the minimum value */
00100     if (out > minVal1)
00101     {
00102       /* Update the minimum value and its index */
00103       out = minVal1;
00104       outIndex = count + 3U;
00105     }
00106 
00107     /* compare for the minimum value */
00108     if (out > minVal2)
00109     {
00110       /* Update the minimum value and its index */
00111       out = minVal2;
00112       outIndex = count + 4U;
00113     }
00114 
00115     count += 4U;
00116 
00117     /* Decrement the loop counter */
00118     blkCnt--;
00119   }
00120 
00121   /* if (blockSize - 1U) is not multiple of 4 */
00122   blkCnt = (blockSize - 1U) % 4U;
00123 
00124 #else
00125   /* Run the below code for Cortex-M0 */
00126 
00127   q31_t minVal1, out;                            /* Temporary variables to store the output value. */
00128   uint32_t blkCnt, outIndex;                     /* loop counter */
00129 
00130   /* Initialise the index value to zero. */
00131   outIndex = 0U;
00132   /* Load first input value that act as reference value for comparision */
00133   out = *pSrc++;
00134 
00135   blkCnt = (blockSize - 1U);
00136 
00137 #endif /* #if defined (ARM_MATH_DSP) */
00138 
00139   while (blkCnt > 0U)
00140   {
00141     /* Initialize minVal to the next consecutive values one by one */
00142     minVal1 = *pSrc++;
00143 
00144     /* compare for the minimum value */
00145     if (out > minVal1)
00146     {
00147       /* Update the minimum value and it's index */
00148       out = minVal1;
00149       outIndex = blockSize - blkCnt;
00150     }
00151 
00152     /* Decrement the loop counter */
00153     blkCnt--;
00154   }
00155 
00156   /* Store the minimum value and it's index into destination pointers */
00157   *pResult = out;
00158   *pIndex = outIndex;
00159 }
00160 
00161 /**
00162  * @} end of Min group
00163  */
00164