arm_max_f32.c

00001 /* ----------------------------------------------------------------------    
00002 * Copyright (C) 2010-2014 ARM Limited. All rights reserved.    
00003 *    
00004 * $Date:        19. March 2015
00005 * $Revision:    V.1.4.5  
00006 *    
00007 * Project:      CMSIS DSP Library    
00008 * Title:        arm_max_f32.c    
00009 *    
00010 * Description:  Maximum value of a floating-point vector.    
00011 *    
00012 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
00013 *  
00014 * Redistribution and use in source and binary forms, with or without 
00015 * modification, are permitted provided that the following conditions
00016 * are met:
00017 *   - Redistributions of source code must retain the above copyright
00018 *     notice, this list of conditions and the following disclaimer.
00019 *   - Redistributions in binary form must reproduce the above copyright
00020 *     notice, this list of conditions and the following disclaimer in
00021 *     the documentation and/or other materials provided with the 
00022 *     distribution.
00023 *   - Neither the name of ARM LIMITED nor the names of its contributors
00024 *     may be used to endorse or promote products derived from this
00025 *     software without specific prior written permission.
00026 *
00027 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
00028 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
00029 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
00030 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 
00031 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
00032 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
00033 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
00034 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
00035 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
00036 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
00037 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
00038 * POSSIBILITY OF SUCH DAMAGE.     
00039 * ---------------------------------------------------------------------------- */
00040 
00041 #include "arm_math.h"
00042 
00043 /**    
00044  * @ingroup groupStats    
00045  */
00046 
00047 /**    
00048  * @defgroup Max Maximum    
00049  *    
00050  * Computes the maximum value of an array of data.     
00051  * The function returns both the maximum value and its position within the array.     
00052  * There are separate functions for floating-point, Q31, Q15, and Q7 data types.    
00053  */
00054 
00055 /**    
00056  * @addtogroup Max    
00057  * @{    
00058  */
00059 
00060 
00061 /**    
00062  * @brief Maximum value of a floating-point vector.    
00063  * @param[in]       *pSrc points to the input vector    
00064  * @param[in]       blockSize length of the input vector    
00065  * @param[out]      *pResult maximum value returned here    
00066  * @param[out]      *pIndex index of maximum value returned here    
00067  * @return none.    
00068  */
00069 
00070 void arm_max_f32(
00071   float32_t * pSrc,
00072   uint32_t blockSize,
00073   float32_t * pResult,
00074   uint32_t * pIndex)
00075 {
00076 #ifndef ARM_MATH_CM0_FAMILY
00077 
00078   /* Run the below code for Cortex-M4 and Cortex-M3 */
00079   float32_t maxVal1, maxVal2, out;               /* Temporary variables to store the output value. */
00080   uint32_t blkCnt, outIndex, count;              /* loop counter */
00081 
00082   /* Initialise the count value. */
00083   count = 0u;
00084   /* Initialise the index value to zero. */
00085   outIndex = 0u;
00086   /* Load first input value that act as reference value for comparision */
00087   out = *pSrc++;
00088 
00089   /* Loop unrolling */
00090   blkCnt = (blockSize - 1u) >> 2u;
00091 
00092   /* Run the below code for Cortex-M4 and Cortex-M3 */
00093   while(blkCnt > 0u)
00094   {
00095     /* Initialize maxVal to the next consecutive values one by one */
00096     maxVal1 = *pSrc++;
00097 
00098     maxVal2 = *pSrc++;
00099 
00100     /* compare for the maximum value */
00101     if(out < maxVal1)
00102     {
00103       /* Update the maximum value and its index */
00104       out = maxVal1;
00105       outIndex = count + 1u;
00106     }
00107 
00108     maxVal1 = *pSrc++;
00109 
00110     /* compare for the maximum value */
00111     if(out < maxVal2)
00112     {
00113       /* Update the maximum value and its index */
00114       out = maxVal2;
00115       outIndex = count + 2u;
00116     }
00117 
00118     maxVal2 = *pSrc++;
00119 
00120     /* compare for the maximum value */
00121     if(out < maxVal1)
00122     {
00123       /* Update the maximum value and its index */
00124       out = maxVal1;
00125       outIndex = count + 3u;
00126     }
00127 
00128     /* compare for the maximum value */
00129     if(out < maxVal2)
00130     {
00131       /* Update the maximum value and its index */
00132       out = maxVal2;
00133       outIndex = count + 4u;
00134     }
00135 
00136     count += 4u;
00137 
00138     /* Decrement the loop counter */
00139     blkCnt--;
00140   }
00141 
00142   /* if (blockSize - 1u) is not multiple of 4 */
00143   blkCnt = (blockSize - 1u) % 4u;
00144 
00145 #else
00146 
00147   /* Run the below code for Cortex-M0 */
00148   float32_t maxVal1, out;                        /* Temporary variables to store the output value. */
00149   uint32_t blkCnt, outIndex;                     /* loop counter */
00150 
00151   /* Initialise the index value to zero. */
00152   outIndex = 0u;
00153   /* Load first input value that act as reference value for comparision */
00154   out = *pSrc++;
00155 
00156   blkCnt = (blockSize - 1u);
00157 
00158 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
00159 
00160   while(blkCnt > 0u)
00161   {
00162     /* Initialize maxVal to the next consecutive values one by one */
00163     maxVal1 = *pSrc++;
00164 
00165     /* compare for the maximum value */
00166     if(out < maxVal1)
00167     {
00168       /* Update the maximum value and it's index */
00169       out = maxVal1;
00170       outIndex = blockSize - blkCnt;
00171     }
00172 
00173 
00174     /* Decrement the loop counter */
00175     blkCnt--;
00176 
00177   }
00178 
00179   /* Store the maximum value and it's index into destination pointers */
00180   *pResult = out;
00181   *pIndex = outIndex;
00182 }
00183 
00184 /**    
00185  * @} end of Max group    
00186  */