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      1 /****************************************************************************
      2 * Copyright (C) 2014-2015 Intel Corporation.   All Rights Reserved.
      3 *
      4 * Permission is hereby granted, free of charge, to any person obtaining a
      5 * copy of this software and associated documentation files (the "Software"),
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      9 * Software is furnished to do so, subject to the following conditions:
     10 *
     11 * The above copyright notice and this permission notice (including the next
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     13 * Software.
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     21 * IN THE SOFTWARE.
     22 *
     23 * @file knobs_init.h
     24 *
     25 * @brief Dynamic Knobs Initialization for Core.
     26 *
     27 ******************************************************************************/
     28 #pragma once
     29 
     30 #include <core/knobs.h>
     31 #include <stdlib.h>
     32 #include <string.h>
     33 #include <ctype.h>
     34 #include <stdio.h>
     35 
     36 // Assume the type is compatible with a 32-bit integer
     37 template <typename T>
     38 static inline void ConvertEnvToKnob(const char* pOverride, T& knobValue)
     39 {
     40     uint32_t value = 0;
     41     char* pStopped = nullptr;
     42     value = strtoul(pOverride, &pStopped, 0);
     43     if (pStopped != pOverride)
     44     {
     45         knobValue = static_cast<T>(value);
     46     }
     47 }
     48 
     49 static inline void ConvertEnvToKnob(const char* pOverride, bool& knobValue)
     50 {
     51     size_t len = strlen(pOverride);
     52     if (len == 1)
     53     {
     54         auto c = tolower(pOverride[0]);
     55         if (c == 'y' || c == 't' || c == '1')
     56         {
     57             knobValue = true;
     58             return;
     59         }
     60         if (c == 'n' || c == 'f' || c == '0')
     61         {
     62             knobValue = false;
     63             return;
     64         }
     65     }
     66 
     67     // Try converting to a number and casting to bool
     68     uint32_t value = 0;
     69     char* pStopped = nullptr;
     70     value = strtoul(pOverride, &pStopped, 0);
     71     if (pStopped != pOverride)
     72     {
     73         knobValue = value != 0;
     74     }
     75 }
     76 
     77 static inline void ConvertEnvToKnob(const char* pOverride, float& knobValue)
     78 {
     79     float value = knobValue;
     80     if (sscanf(pOverride, "%f", &value))
     81     {
     82         knobValue = value;
     83     }
     84 }
     85 
     86 static inline void ConvertEnvToKnob(const char* pOverride, std::string& knobValue)
     87 {
     88     knobValue = pOverride;
     89 }
     90 
     91 template <typename T>
     92 static inline void InitKnob(T& knob)
     93 {
     94 
     95     // TODO, read registry first
     96 
     97     // Second, read environment variables
     98     const char* pOverride = getenv(knob.Name());
     99 
    100     if (pOverride)
    101     {
    102         auto knobValue = knob.Value();
    103         ConvertEnvToKnob(pOverride, knobValue);
    104         knob.Value(knobValue);
    105     }
    106 }
    107