arm_max_f32.c

00001 /* ----------------------------------------------------------------------
00002  * Project:      CMSIS DSP Library
00003  * Title:        arm_max_f32.c
00004  * Description:  Maximum value of a floating-point 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  * @defgroup Max Maximum
00037  *
00038  * Computes the maximum value of an array of data.
00039  * The function returns both the maximum value and its position within the array.
00040  * There are separate functions for floating-point, Q31, Q15, and Q7 data types.
00041  */
00042 
00043 /**
00044  * @addtogroup Max
00045  * @{
00046  */
00047 
00048 
00049 /**
00050  * @brief Maximum value of a floating-point vector.
00051  * @param[in]       *pSrc points to the input vector
00052  * @param[in]       blockSize length of the input vector
00053  * @param[out]      *pResult maximum value returned here
00054  * @param[out]      *pIndex index of maximum value returned here
00055  * @return none.
00056  */
00057 
00058 void arm_max_f32(
00059   float32_t * pSrc,
00060   uint32_t blockSize,
00061   float32_t * pResult,
00062   uint32_t * pIndex)
00063 {
00064 #if defined (ARM_MATH_DSP)
00065   /* Run the below code for Cortex-M4 and Cortex-M3 */
00066 
00067   float32_t maxVal1, maxVal2, out;               /* Temporary variables to store the output value. */
00068   uint32_t blkCnt, outIndex, count;              /* loop counter */
00069 
00070   /* Initialise the count value. */
00071   count = 0U;
00072   /* Initialise the index value to zero. */
00073   outIndex = 0U;
00074   /* Load first input value that act as reference value for comparision */
00075   out = *pSrc++;
00076 
00077   /* Loop unrolling */
00078   blkCnt = (blockSize - 1U) >> 2U;
00079 
00080   while (blkCnt > 0U)
00081   {
00082     /* Initialize maxVal to the next consecutive values one by one */
00083     maxVal1 = *pSrc++;
00084     maxVal2 = *pSrc++;
00085 
00086     /* compare for the maximum value */
00087     if (out < maxVal1)
00088     {
00089       /* Update the maximum value and its index */
00090       out = maxVal1;
00091       outIndex = count + 1U;
00092     }
00093 
00094     /* compare for the maximum value */
00095     if (out < maxVal2)
00096     {
00097       /* Update the maximum value and its index */
00098       out = maxVal2;
00099       outIndex = count + 2U;
00100     }
00101 
00102     /* Initialize maxVal to the next consecutive values one by one */
00103     maxVal1 = *pSrc++;
00104     maxVal2 = *pSrc++;
00105 
00106     /* compare for the maximum value */
00107     if (out < maxVal1)
00108     {
00109       /* Update the maximum value and its index */
00110       out = maxVal1;
00111       outIndex = count + 3U;
00112     }
00113 
00114     /* compare for the maximum value */
00115     if (out < maxVal2)
00116     {
00117       /* Update the maximum value and its index */
00118       out = maxVal2;
00119       outIndex = count + 4U;
00120     }
00121 
00122     count += 4U;
00123 
00124     /* Decrement the loop counter */
00125     blkCnt--;
00126   }
00127 
00128   /* if (blockSize - 1U) is not multiple of 4 */
00129   blkCnt = (blockSize - 1U) % 4U;
00130 
00131 #else
00132   /* Run the below code for Cortex-M0 */
00133 
00134   float32_t maxVal1, out;                        /* Temporary variables to store the output value. */
00135   uint32_t blkCnt, outIndex;                     /* loop counter */
00136 
00137   /* Initialise the index value to zero. */
00138   outIndex = 0U;
00139   /* Load first input value that act as reference value for comparision */
00140   out = *pSrc++;
00141 
00142   blkCnt = (blockSize - 1U);
00143 
00144 #endif /* #if defined (ARM_MATH_DSP) */
00145 
00146   while (blkCnt > 0U)
00147   {
00148     /* Initialize maxVal to the next consecutive values one by one */
00149     maxVal1 = *pSrc++;
00150 
00151     /* compare for the maximum value */
00152     if (out < maxVal1)
00153     {
00154       /* Update the maximum value and it's index */
00155       out = maxVal1;
00156       outIndex = blockSize - blkCnt;
00157     }
00158 
00159     /* Decrement the loop counter */
00160     blkCnt--;
00161   }
00162 
00163   /* Store the maximum value and it's index into destination pointers */
00164   *pResult = out;
00165   *pIndex = outIndex;
00166 }
00167 
00168 /**
00169  * @} end of Max group
00170  */
00171