arm_min_q7.c

00001 /* ----------------------------------------------------------------------  
00002 * Copyright (C) 2010 ARM Limited. All rights reserved.  
00003 *  
00004 * $Date:        29. November 2010  
00005 * $Revision:    V1.0.3  
00006 *  
00007 * Project:      CMSIS DSP Library  
00008 * Title:        arm_min_q7.c  
00009 *  
00010 * Description:  Processing function for the Q7 Minimum.  
00011 *  
00012 * Target Processor: Cortex-M4/Cortex-M3
00013 *  
00014 * Version 1.0.3 2010/11/29 
00015 *    Re-organized the CMSIS folders and updated documentation.  
00016 *   
00017 * Version 1.0.2 2010/11/11  
00018 *    Documentation updated.   
00019 *  
00020 * Version 1.0.1 2010/10/05   
00021 *    Production release and review comments incorporated.  
00022 *  
00023 * Version 1.0.0 2010/09/20   
00024 *    Production release and review comments incorporated.  
00025 * ---------------------------------------------------------------------------- */ 
00026  
00027 #include "arm_math.h" 
00028  
00029 /**  
00030  * @ingroup groupStats  
00031  */ 
00032  
00033 /**  
00034  * @addtogroup Min  
00035  * @{  
00036  */ 
00037  
00038  
00039 /**  
00040  * @brief Minimum value of a Q7 vector.  
00041  * @param[in]       *pSrc points to the input vector  
00042  * @param[in]       blockSize length of the input vector  
00043  * @param[out]      *pResult minimum value returned here  
00044  * @param[out]      *pIndex index of minimum value returned here  
00045  * @return none.  
00046  *  
00047  */ 
00048  
00049 void arm_min_q7( 
00050   q7_t * pSrc, 
00051   uint32_t blockSize, 
00052   q7_t * pResult, 
00053   uint32_t * pIndex) 
00054 { 
00055   q7_t minVal, minVal1, minVal2, res, x0, x1;    /* Temporary variables to store the output value. */ 
00056   uint32_t blkCnt, indx, index1, index2, index3, indxMod;       /* loop counter */ 
00057  
00058   /* Initialise the index value to zero. */ 
00059   indx = 0u; 
00060  
00061   /* Load first input value that act as reference value for comparision */ 
00062   res = *pSrc++; 
00063  
00064   /* Loop over blockSize number of values */ 
00065   blkCnt = (blockSize - 1u) >> 2u; 
00066  
00067   while(blkCnt > 0u) 
00068   { 
00069     indxMod = blockSize - (blkCnt * 4u); 
00070  
00071     /* Load two input values for comparision */ 
00072     x0 = *pSrc++; 
00073     x1 = *pSrc++; 
00074  
00075     if(x0 > x1) 
00076     { 
00077       /* Update the minimum value and its index */ 
00078       minVal1 = x1; 
00079       index1 = indxMod + 1u; 
00080     } 
00081     else 
00082     { 
00083       /* Update the minimum value and its index */ 
00084       minVal1 = x0; 
00085       index1 = indxMod; 
00086     } 
00087  
00088     /* Load two input values for comparision */ 
00089     x0 = *pSrc++; 
00090     x1 = *pSrc++; 
00091  
00092     if(x0 > x1) 
00093     { 
00094       /* Update the minimum value and its index */ 
00095       minVal2 = x1; 
00096       index2 = indxMod + 3u; 
00097     } 
00098     else 
00099     { 
00100       /* Update the minimum value and its index */ 
00101       minVal2 = x0; 
00102       index2 = indxMod + 2u; 
00103     } 
00104  
00105     if(minVal1 > minVal2) 
00106     { 
00107       /* Update the minimum value and its index */ 
00108       minVal = minVal2; 
00109       index3 = index2; 
00110     } 
00111     else 
00112     { 
00113       /* Update the minimum value and its index */ 
00114       minVal = minVal1; 
00115       index3 = index1; 
00116     } 
00117  
00118     if(res > minVal) 
00119     { 
00120       /* Update the minimum value and its index */ 
00121       res = minVal; 
00122       indx = index3; 
00123     } 
00124  
00125     /* Decrement the loop counter */ 
00126     blkCnt--; 
00127  
00128   } 
00129  
00130   blkCnt = (blockSize - 1u) % 0x04u; 
00131  
00132   while(blkCnt > 0u) 
00133   { 
00134     /* Initialize minVal to the next consecutive values one by one */ 
00135     minVal = *pSrc++; 
00136  
00137     /* compare for the minimum value */ 
00138     if(res > minVal) 
00139     { 
00140       /* Update the minimum value and its index */ 
00141       res = minVal; 
00142       indx = blockSize - blkCnt; 
00143     } 
00144  
00145     /* Decrement the loop counter */ 
00146     blkCnt--; 
00147   } 
00148  
00149   /* Store the minimum value and its index into destination pointers */ 
00150   *pResult = res; 
00151   *pIndex = indx; 
00152 } 
00153  
00154 /**  
00155  * @} end of Min group  
00156  */