00001 /* ---------------------------------------------------------------------- 00002 * Copyright (C) 2010 ARM Limited. All rights reserved. 00003 * 00004 * $Date: 15. July 2011 00005 * $Revision: V1.0.10 00006 * 00007 * Project: CMSIS DSP Library 00008 * Title: arm_max_q7.c 00009 * 00010 * Description: Maximum value of a Q7 vector. 00011 * 00012 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0 00013 * 00014 * Version 1.0.10 2011/7/15 00015 * Big Endian support added and Merged M0 and M3/M4 Source code. 00016 * 00017 * Version 1.0.3 2010/11/29 00018 * Re-organized the CMSIS folders and updated documentation. 00019 * 00020 * Version 1.0.2 2010/11/11 00021 * Documentation updated. 00022 * 00023 * Version 1.0.1 2010/10/05 00024 * Production release and review comments incorporated. 00025 * 00026 * Version 1.0.0 2010/09/20 00027 * Production release and review comments incorporated. 00028 * ---------------------------------------------------------------------------- */ 00029 00030 #include "arm_math.h" 00031 00051 void arm_max_q7( 00052 q7_t * pSrc, 00053 uint32_t blockSize, 00054 q7_t * pResult, 00055 uint32_t * pIndex) 00056 { 00057 00058 #ifndef ARM_MATH_CM0 00059 00060 /* Run the below code for Cortex-M4 and Cortex-M3 */ 00061 00062 q7_t res, maxVal, x0, x1, maxVal2, maxVal1; /* Temporary variables to store the output value. */ 00063 uint32_t blkCnt, index1, index2, index3, indx, indxMod; /* loop counter */ 00064 00065 /* Initialise the index value to zero. */ 00066 indx = 0u; 00067 00068 /* Load first input value that act as reference value for comparision */ 00069 res = *pSrc++; 00070 00071 /* Loop unrolling */ 00072 blkCnt = (blockSize - 1u) >> 2u; 00073 00074 /* First part of the processing with loop unrolling. Compute 4 outputs at a time. 00075 ** a second loop below computes the remaining 1 to 3 samples. */ 00076 while(blkCnt > 0u) 00077 { 00078 indxMod = blockSize - (blkCnt * 4u); 00079 00080 /* Load two input values for comparision */ 00081 x0 = *pSrc++; 00082 x1 = *pSrc++; 00083 00084 if(x0 < x1) 00085 { 00086 /* Update the maximum value and its index */ 00087 maxVal1 = x1; 00088 index1 = indxMod + 1u; 00089 } 00090 else 00091 { 00092 /* Update the maximum value and its index */ 00093 maxVal1 = x0; 00094 index1 = indxMod; 00095 } 00096 00097 /* Load two input values for comparision */ 00098 x0 = *pSrc++; 00099 x1 = *pSrc++; 00100 00101 if(x0 < x1) 00102 { 00103 /* Update the maximum value and its index */ 00104 maxVal2 = x1; 00105 index2 = indxMod + 3u; 00106 } 00107 else 00108 { 00109 /* Update the maximum value and its index */ 00110 maxVal2 = x0; 00111 index2 = indxMod + 2u; 00112 } 00113 00114 if(maxVal1 < maxVal2) 00115 { 00116 /* Update the maximum value and its index */ 00117 maxVal = maxVal2; 00118 index3 = index2; 00119 } 00120 else 00121 { 00122 /* Update the maximum value and its index */ 00123 maxVal = maxVal1; 00124 index3 = index1; 00125 } 00126 00127 if(res < maxVal) 00128 { 00129 /* Update the maximum value and its index */ 00130 res = maxVal; 00131 indx = index3; 00132 } 00133 00134 /* Decrement the loop counter */ 00135 blkCnt--; 00136 00137 } 00138 00139 /* If the blockSize - 1 is not a multiple of 4, compute any remaining output samples here. 00140 ** No loop unrolling is used. */ 00141 blkCnt = (blockSize - 1u) % 0x04u; 00142 00143 while(blkCnt > 0u) 00144 { 00145 /* Initialize maxVal to the next consecutive values one by one */ 00146 maxVal = *pSrc++; 00147 00148 /* compare for the maximum value */ 00149 if(res < maxVal) 00150 { 00151 /* Update the maximum value and its index */ 00152 res = maxVal; 00153 indx = blockSize - blkCnt; 00154 } 00155 00156 /* Decrement the loop counter */ 00157 blkCnt--; 00158 } 00159 00160 /* Store the maximum value and its index into destination pointers */ 00161 *pResult = res; 00162 *pIndex = indx; 00163 00164 #else 00165 00166 /* Run the below code for Cortex-M0 */ 00167 00168 q7_t maxVal, out; /* Temporary variables to store the output value. */ 00169 uint32_t blkCnt, outIndex; /* loop counter */ 00170 00171 /* Initialise the index value to zero. */ 00172 outIndex = 0u; 00173 /* Load first input value that act as reference value for comparision */ 00174 out = *pSrc++; 00175 00176 /* Loop over blockSize - 1 number of values */ 00177 blkCnt = (blockSize - 1u); 00178 00179 while(blkCnt > 0u) 00180 { 00181 /* Initialize maxVal to the next consecutive values one by one */ 00182 maxVal = *pSrc++; 00183 00184 /* compare for the maximum value */ 00185 if(out < maxVal) 00186 { 00187 /* Update the maximum value and its index */ 00188 out = maxVal; 00189 outIndex = blockSize - blkCnt; 00190 } 00191 /* Decrement the loop counter */ 00192 blkCnt--; 00193 00194 } 00195 00196 /* Store the maximum value and its index into destination pointers */ 00197 *pResult = out; 00198 *pIndex = outIndex; 00199 00200 #endif /* #ifndef ARM_MATH_CM0 */ 00201 00202 } 00203