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CRC.h
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CRC.h
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#pragma once
#include <ASMMacros.h>
#include <Helpers/CompileTime.h>
class CRCEngine
{
public:
int operator()() const
{
return Value();
}
// Commented out because Ares reimplemented it already!
//
// void operator()(char datum)
// {
// StagingBuffer.Buffer[Index++] = datum;
//
// if (Index == sizeof(int))
// {
// CRC = Value();
// StagingBuffer.Composite = 0;
// Index = 0;
// }
// }
//
// int operator()(void* buffer, int length)
// {
// return (*this)((const void*)buffer, length);
// }
//
// int operator()(const void* buffer, int length)
// {
// if (buffer != nullptr && length > 0)
// {
// const char* dataptr = (char const*)buffer;
// int bytes_left = length;
//
// while (bytes_left && Buffer_Needs_Data())
// {
// operator()(*dataptr);
// ++dataptr;
// --bytes_left;
// }
//
// const int* intptr = (const int*)dataptr;
// int intcount = bytes_left / sizeof(int);
// while (intcount--)
// {
// CRC = Memory(intptr, 4, CRC);
// ++intptr;
// bytes_left -= sizeof(int);
// }
//
// dataptr = (char const*)intptr;
// while (bytes_left)
// {
// operator()(*dataptr);
// ++dataptr;
// --bytes_left;
// }
// }
//
// return Value();
// }
template<typename T>
int operator()(const T& data)
{
return (*this)((const void*)&data, static_cast<int>(sizeof(data)));
}
operator int() const
{
return Value();
}
void operator()(char datum)
{
JMP_THIS(0x4A1C10);
}
void operator()(bool datum)
{
JMP_THIS(0x4A1CA0);
}
void operator()(short datum)
{
JMP_THIS(0x4A1D30);
}
void operator()(int datum)
{
JMP_THIS(0x4A1D50);
}
void operator()(float datum)
{
JMP_THIS(0x4A1D70);
}
void operator()(double datum)
{
JMP_THIS(0x4A1D90);
}
int operator()(const void* buffer, int length)
{
JMP_THIS(0x4A1DE0);
}
static constexpr reference<unsigned int, 0x81F7B4, 256> const Table {};
static int Memory(const void* data, int bytes, int crc)
{
auto buffer = reinterpret_cast<const unsigned char*>(data);
unsigned int ret = ~crc;
for (int i = 0; i < bytes; ++i)
ret = (ret >> 8) ^ Table[*buffer++ ^ (ret & 0xFF)];
return ~ret;
}
static int String(const char* buffer, int crc)
{
unsigned int ret = ~crc;
while (*buffer)
ret = (ret >> 8) ^ Table[*buffer++ ^ (ret & 0xFF)];
return ~ret;
}
protected:
bool Buffer_Needs_Data() const
{
return Index != 0;
}
int Value() const
{
if (!Buffer_Needs_Data())
return CRC;
(char&)StagingBuffer.Buffer[Index] = (char)Index;
for (int i = Index + 1; i < 4; ++i)
(char&)StagingBuffer.Buffer[i] = this->StagingBuffer.Buffer[0];
return Memory(StagingBuffer.Buffer, 4, CRC);
}
public:
int CRC;
int Index;
union
{
int Composite;
char Buffer[sizeof(int)];
} StagingBuffer;
};