enderalse/source/fs.dll/common/IFIFO.cpp

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2021-10-06 00:45:46 +00:00
#include "IFIFO.h"
IFIFO::IFIFO(UInt32 length)
{
fifoBuf = new UInt8[length];
fifoBufSize = length;
fifoBase = 0;
fifoDataLength = 0;
}
IFIFO::~IFIFO()
{
delete fifoBuf;
}
bool IFIFO::Push(UInt8 * buf, UInt32 length)
{
// would that overflow the buffer?
if(length > GetBufferRemain())
return false;
UInt32 writeOffset = GetWriteOffset();
// will this cross the end of the buffer?
if(writeOffset + length > fifoBufSize)
{
UInt32 segmentLength = fifoBufSize - writeOffset;
std::memcpy(&fifoBuf[writeOffset], buf, segmentLength);
std::memcpy(fifoBuf, &buf[segmentLength], length - segmentLength);
}
else
{
std::memcpy(&fifoBuf[writeOffset], buf, length);
}
// update pointers
fifoDataLength += length;
return true;
}
bool IFIFO::Pop(UInt8 * buf, UInt32 length)
{
bool result = Peek(buf, length);
// update pointers if we were successful
if(result)
{
fifoDataLength -= length;
fifoBase = ToRawOffset(fifoBase + length);
}
return result;
}
bool IFIFO::Peek(UInt8 * buf, UInt32 length)
{
// would that underflow the buffer?
if(length > fifoDataLength)
return false;
// will this cross the end of the buffer?
if(fifoBase + length > fifoBufSize)
{
UInt32 segmentLength = fifoBufSize - fifoBase;
std::memcpy(buf, &fifoBuf[fifoBase], segmentLength);
std::memcpy(&buf[segmentLength], fifoBuf, length - segmentLength);
}
else
{
std::memcpy(buf, &fifoBuf[fifoBase], length);
}
return true;
}
void IFIFO::Clear(void)
{
fifoDataLength = 0;
// this isn't needed, but staying away from the buffer end is always good
fifoBase = 0;
}