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      1 /*
      2  * Copyright (C) 2011 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 /**
     17  ************************************************************************
     18  * @file        M4PSW_Trace.c
     19  * @brief        Trace function for trace macros
     20  * @note        This file gives the implementation of the trace function used
     21  *                in the trace instrumentation macros
     22  ************************************************************************
     23 */
     24 
     25 #include <stdio.h>  /*for printf */
     26 #include <stdarg.h> /* ANSI C macros and defs for variable args */
     27 #include <stdlib.h>
     28 #include <string.h>
     29 #include <time.h>
     30 
     31 #include "M4OSA_Types.h"
     32 #include "M4OSA_Error.h"
     33 #include "M4OSA_Memory.h"
     34 #include "M4OSA_Mutex.h"
     35 /**
     36  ************************************************************************
     37  * @fn         M4OSA_ERR M4OSA_randInit()
     38  * @brief      this function initialize the number generator
     39  *               this function must be called once before any call to M4OSA_rand()
     40  *               need the stdlib and time libraries
     41  * @note
     42  * @param
     43  * @return     M4NO_ERROR
     44  ************************************************************************
     45 */
     46 
     47 M4OSA_ERR M4OSA_randInit()
     48 {
     49     int i;
     50 
     51     srand(time(NULL));
     52 
     53     /* Windows' rand is rotten, the first generated value after the init
     54     above is not random enough, so let's shake things a little... */
     55 
     56     for (i=0; i<100; i++) rand();
     57 
     58     return M4NO_ERROR;
     59 }
     60 /**
     61  ************************************************************************
     62  * @fn           M4OSA_ERR M4OSA_rand(M4OSA_Int32* out_value, M4OSA_UInt32 max_value)
     63  * @brief       This function gives a random number between 1 and max_value
     64  *               (inclusive) with approximately equal probability, and
     65  *               returns this number in out_value. For instance, a max_value
     66  *             of 6 will simulate a fair 6-sided dice roll.
     67  * @note
     68  * @param      out_value (OUT): on return, points to random result
     69  * @param       max_value (IN): max expected value
     70  * @return     M4NO_ERROR
     71  ************************************************************************
     72 */
     73 
     74 M4OSA_ERR M4OSA_rand(M4OSA_Int32* out_value, M4OSA_UInt32 max_value)
     75 {
     76     if( (out_value == M4OSA_NULL) || (max_value < 1) )
     77     {
     78         return M4ERR_PARAMETER;
     79     }
     80 
     81     (*out_value) = rand();
     82     /* notice this algorithm will only work for max_values such that the multiplication
     83     won't overflow, which means that max_value typically shouldn't go over the range of
     84     an Int16. */
     85     (*out_value) = (((*out_value) * max_value) / ((M4OSA_UInt32)RAND_MAX + 1)) + 1;
     86 
     87     return M4NO_ERROR;
     88 }
     89 
     90 
     91