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 #pragma once
 
 // Copyright (C) 2002-2007 Nikolaus Gebhardt
 // This file is part of the "Irrlicht Engine" and the "irrXML" project.
 // For conditions of distribution and use, see copyright notice in irrlicht.h and irrXML.h
 
 // ------------------------------------------------------------------------------------
 // Original description: (Schrompf)
 // Adapted to the ASSIMP library because the builtin atof indeed takes AGES to parse a
 // float inside a large string. Before parsing, it does a strlen on the given point.
 // Changes:
 //  22nd October 08 (Aramis_acg): Added temporary cast to double, added strtoul10_64
 //     to ensure long numbers are handled correctly
 // ------------------------------------------------------------------------------------
 
 #pragma once
 #ifndef FAST_A_TO_F_H_INCLUDED
 #define FAST_A_TO_F_H_INCLUDED
 
 #ifdef __GNUC__
 #   pragma GCC system_header
 #endif
 
 #include <cmath>
 #include <limits>
 #include <stdint.h>
 #include <assimp/defs.h>
 
 #include "StringComparison.h"
 #include <assimp/DefaultLogger.hpp>
 #include <assimp/Exceptional.h>
 #include <assimp/StringUtils.h>
 
 #ifdef _MSC_VER
 #  include <stdint.h>
 #else
 #  include <assimp/Compiler/pstdint.h>
 #endif
 
 namespace Assimp {
 
 static constexpr size_t NumItems = 16;
 
 constexpr double fast_atof_table[NumItems] =  {  // we write [16] here instead of [] to work around a swig bug
     0.0,
     0.1,
     0.01,
     0.001,
     0.0001,
     0.00001,
     0.000001,
     0.0000001,
     0.00000001,
     0.000000001,
     0.0000000001,
     0.00000000001,
     0.000000000001,
     0.0000000000001,
     0.00000000000001,
     0.000000000000001
 };
 
 // ------------------------------------------------------------------------------------
 // Convert a string in decimal format to a number
 // ------------------------------------------------------------------------------------
 inline unsigned int strtoul10( const char* in, const char** out=0) {
     unsigned int value = 0;
 
     for ( ;; ) {
         if ( *in < '0' || *in > '9' ) {
             break;
         }
 
         value = ( value * 10 ) + ( *in - '0' );
         ++in;
     }
     if ( out ) {
         *out = in;
     }
     return value;
 }
 
 // ------------------------------------------------------------------------------------
 // Convert a string in octal format to a number
 // ------------------------------------------------------------------------------------
 inline unsigned int strtoul8( const char* in, const char** out=0) {
     unsigned int value( 0 );
     for ( ;; ) {
         if ( *in < '0' || *in > '7' ) {
             break;
         }
 
         value = ( value << 3 ) + ( *in - '0' );
         ++in;
     }
     if ( out ) {
         *out = in;
     }
     return value;
 }
 
 // ------------------------------------------------------------------------------------
 // Convert a string in hex format to a number
 // ------------------------------------------------------------------------------------
 inline unsigned int strtoul16( const char* in, const char** out=0) {
     unsigned int value( 0 );
     for ( ;; ) {
         if ( *in >= '0' && *in <= '9' ) {
             value = ( value << 4u ) + ( *in - '0' );
         } else if (*in >= 'A' && *in <= 'F') {
             value = ( value << 4u ) + ( *in - 'A' ) + 10;
         } else if (*in >= 'a' && *in <= 'f') {
             value = ( value << 4u ) + ( *in - 'a' ) + 10;
         } else {
             break;
         }
         ++in;
     }
     if ( out ) {
         *out = in;
     }
     return value;
 }
 
 // ------------------------------------------------------------------------------------
 // Convert just one hex digit
 // Return value is UINT_MAX if the input character is not a hex digit.
 // ------------------------------------------------------------------------------------
 inline unsigned int HexDigitToDecimal(char in) {
     unsigned int out( UINT_MAX );
     if ( in >= '0' && in <= '9' ) {
         out = in - '0';
     } else if ( in >= 'a' && in <= 'f' ) {
         out = 10u + in - 'a';
     } else if ( in >= 'A' && in <= 'F' ) {
         out = 10u + in - 'A';
     }
 
     // return value is UINT_MAX if the input is not a hex digit
     return out;
 }
 
 // ------------------------------------------------------------------------------------
 // Convert a hex-encoded octet (2 characters, i.e. df or 1a).
 // ------------------------------------------------------------------------------------
 inline uint8_t HexOctetToDecimal(const char* in) {
     return ((uint8_t)HexDigitToDecimal(in[0])<<4)+(uint8_t)HexDigitToDecimal(in[1]);
 }
 
 // ------------------------------------------------------------------------------------
 // signed variant of strtoul10
 // ------------------------------------------------------------------------------------
 inline int strtol10( const char* in, const char** out = 0) {
     bool inv = (*in=='-');
     if ( inv || *in == '+' ) {
         ++in;
     }
 
     int value = strtoul10(in,out);
     if (inv) {
         if (value < INT_MAX && value > INT_MIN) {
             value = -value;
         } else {
             ASSIMP_LOG_WARN( "Converting the string \"", in, "\" into an inverted value resulted in overflow." );
         }
     }
     return value;
 }
 
 // ------------------------------------------------------------------------------------
 // Parse a C++-like integer literal - hex and oct prefixes.
 // 0xNNNN - hex
 // 0NNN   - oct
 // NNN    - dec
 // ------------------------------------------------------------------------------------
 inline unsigned int strtoul_cppstyle( const char* in, const char** out=0) {
     if ('0' == in[0]) {
         return 'x' == in[1] ? strtoul16(in+2,out) : strtoul8(in+1,out);
     }
     return strtoul10(in, out);
 }
 
 // ------------------------------------------------------------------------------------
 // Special version of the function, providing higher accuracy and safety
 // It is mainly used by fast_atof to prevent ugly and unwanted integer overflows.
 // ------------------------------------------------------------------------------------
 template<typename ExceptionType = DeadlyImportError>
 inline uint64_t strtoul10_64( const char* in, const char** out=0, unsigned int* max_inout=0) {
     unsigned int cur = 0;
     uint64_t value = 0;
 
     if ( *in < '0' || *in > '9' ) {
         // The string is known to be bad, so don't risk printing the whole thing.
         throw ExceptionType("The string \"", ai_str_toprintable(in, (int)strlen(in)), "\" cannot be converted into a value." );
     }
 
     for ( ;; ) {
         if ( *in < '0' || *in > '9' ) {
             break;
         }
 
         const uint64_t new_value = ( value * (uint64_t) 10 ) + ( (uint64_t) ( *in - '0' ) );
 
         // numeric overflow, we rely on you
         if ( new_value < value ) {
             ASSIMP_LOG_WARN( "Converting the string \"", in, "\" into a value resulted in overflow." );
             return 0;
         }
 
         value = new_value;
 
         ++in;
         ++cur;
 
         if (max_inout && *max_inout == cur) {
             if (out) { /* skip to end */
                 while ( *in >= '0' && *in <= '9' ) {
                     ++in;
                 }
                 *out = in;
             }
 
             return value;
         }
     }
     if ( out ) {
         *out = in;
     }
 
     if ( max_inout ) {
         *max_inout = cur;
     }
 
     return value;
 }
 
 // ------------------------------------------------------------------------------------
 // signed variant of strtoul10_64
 // ------------------------------------------------------------------------------------
 template<typename ExceptionType = DeadlyImportError>
 inline int64_t strtol10_64(const char* in, const char** out = 0, unsigned int* max_inout = 0) {
     bool inv = (*in == '-');
     if ( inv || *in == '+' ) {
         ++in;
     }
 
     int64_t value = strtoul10_64<ExceptionType>(in, out, max_inout);
     if (inv) {
         value = -value;
     }
     return value;
 }
 
 // Number of relevant decimals for floating-point parsing.
 #define AI_FAST_ATOF_RELAVANT_DECIMALS 15
 
 // ------------------------------------------------------------------------------------
 //! Provides a fast function for converting a string into a float,
 //! about 6 times faster than atof in win32.
 // If you find any bugs, please send them to me, niko (at) irrlicht3d.org.
 // ------------------------------------------------------------------------------------
 template<typename Real, typename ExceptionType = DeadlyImportError>
 inline const char* fast_atoreal_move(const char* c, Real& out, bool check_comma = true) {
     Real f = 0;
 
     bool inv = (*c == '-');
     if (inv || *c == '+') {
         ++c;
     }
 
     if ((c[0] == 'N' || c[0] == 'n') && ASSIMP_strincmp(c, "nan", 3) == 0) {
         out = std::numeric_limits<Real>::quiet_NaN();
         c += 3;
         return c;
     }
 
     if ((c[0] == 'I' || c[0] == 'i') && ASSIMP_strincmp(c, "inf", 3) == 0) {
         out = std::numeric_limits<Real>::infinity();
         if (inv) {
             out = -out;
         }
         c += 3;
         if ((c[0] == 'I' || c[0] == 'i') && ASSIMP_strincmp(c, "inity", 5) == 0) {
             c += 5;
         }
         return c;
      }
 
     if (!(c[0] >= '0' && c[0] <= '9') &&
             !((c[0] == '.' || (check_comma && c[0] == ',')) && c[1] >= '0' && c[1] <= '9')) {
         // The string is known to be bad, so don't risk printing the whole thing.
         throw ExceptionType("Cannot parse string \"", ai_str_toprintable(c, (int)strlen(c)),
                                     "\" as a real number: does not start with digit "
                                     "or decimal point followed by digit.");
     }
 
     if (*c != '.' && (! check_comma || c[0] != ',')) {
         f = static_cast<Real>( strtoul10_64<ExceptionType> ( c, &c) );
     }
 
     if ((*c == '.' || (check_comma && c[0] == ',')) && c[1] >= '0' && c[1] <= '9') {
         ++c;
 
         // NOTE: The original implementation is highly inaccurate here. The precision of a single
         // IEEE 754 float is not high enough, everything behind the 6th digit tends to be more
         // inaccurate than it would need to be. Casting to double seems to solve the problem.
         // strtol_64 is used to prevent integer overflow.
 
         // Another fix: this tends to become 0 for long numbers if we don't limit the maximum
         // number of digits to be read. AI_FAST_ATOF_RELAVANT_DECIMALS can be a value between
         // 1 and 15.
         unsigned int diff = AI_FAST_ATOF_RELAVANT_DECIMALS;
         double pl = static_cast<double>( strtoul10_64<ExceptionType> ( c, &c, &diff ));
 
         pl *= fast_atof_table[diff];
         f += static_cast<Real>( pl );
     }
     // For backwards compatibility: eat trailing dots, but not trailing commas.
     else if (*c == '.') {
         ++c;
     }
 
     // A major 'E' must be allowed. Necessary for proper reading of some DXF files.
     // Thanks to Zhao Lei to point out that this if() must be outside the if (*c == '.' ..)
     if (*c == 'e' || *c == 'E') {
         ++c;
         const bool einv = (*c=='-');
         if (einv || *c=='+') {
             ++c;
         }
 
         // The reason float constants are used here is that we've seen cases where compilers
         // would perform such casts on compile-time constants at runtime, which would be
         // bad considering how frequently fast_atoreal_move<float> is called in Assimp.
         Real exp = static_cast<Real>( strtoul10_64<ExceptionType>(c, &c) );
         if (einv) {
             exp = -exp;
         }
         f *= std::pow(static_cast<Real>(10.0), exp);
     }
 
     if (inv) {
         f = -f;
     }
     out = f;
     return c;
 }
 
 // ------------------------------------------------------------------------------------
 // The same but more human.
 template<typename ExceptionType = DeadlyImportError>
 inline ai_real fast_atof(const char* c) {
     ai_real ret(0.0);
     fast_atoreal_move<ai_real, ExceptionType>(c, ret);
 
     return ret;
 }
 
 template<typename ExceptionType = DeadlyImportError>
 inline
 ai_real fast_atof( const char* c, const char** cout) {
     ai_real ret(0.0);
     *cout = fast_atoreal_move<ai_real, ExceptionType>(c, ret);
 
     return ret;
 }
 
 template<typename ExceptionType = DeadlyImportError>
 inline ai_real fast_atof( const char** inout) {
     ai_real ret(0.0);
     *inout = fast_atoreal_move<ai_real, ExceptionType>(*inout, ret);
 
     return ret;
 }
 
 } //! namespace Assimp
 
 #endif // FAST_A_TO_F_H_INCLUDED

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