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/*
Copyright 2016-2021 Arisotura
This file is part of melonDS.
melonDS is free software: you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation, either version 3 of the License, or (at your option)
any later version.
melonDS is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along
with melonDS. If not, see http://www.gnu.org/licenses/.
*/
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <time.h>
#include <atomic>
#include "NDSCart_SRAMManager.h"
#include "Platform.h"
namespace NDSCart_SRAMManager
{
Platform::Thread* FlushThread;
std::atomic_bool FlushThreadRunning;
Platform::Mutex* SecondaryBufferLock;
char Path[1024];
u8* Buffer;
u32 Length;
u8* SecondaryBuffer;
u32 SecondaryBufferLength;
time_t TimeAtLastFlushRequest;
// We keep versions in case the user closes the application before
// a flush cycle is finished.
u32 PreviousFlushVersion;
u32 FlushVersion;
void FlushThreadFunc();
bool Init()
{
SecondaryBufferLock = Platform::Mutex_Create();
return true;
}
void DeInit()
{
if (FlushThreadRunning)
{
FlushThreadRunning = false;
Platform::Thread_Wait(FlushThread);
Platform::Thread_Free(FlushThread);
FlushSecondaryBuffer();
}
if (SecondaryBuffer) delete[] SecondaryBuffer;
SecondaryBuffer = NULL;
Platform::Mutex_Free(SecondaryBufferLock);
}
void Setup(const char* path, u8* buffer, u32 length)
{
// Flush SRAM in case there is unflushed data from previous state.
FlushSecondaryBuffer();
Platform::Mutex_Lock(SecondaryBufferLock);
strncpy(Path, path, 1023);
Path[1023] = '\0';
Buffer = buffer;
Length = length;
if(SecondaryBuffer) delete[] SecondaryBuffer; // Delete secondary buffer, there might be previous state.
SecondaryBuffer = new u8[length];
SecondaryBufferLength = length;
FlushVersion = 0;
PreviousFlushVersion = 0;
TimeAtLastFlushRequest = 0;
Platform::Mutex_Unlock(SecondaryBufferLock);
if (path[0] != '\0' && !FlushThreadRunning)
{
FlushThread = Platform::Thread_Create(FlushThreadFunc);
FlushThreadRunning = true;
}
else if (path[0] == '\0' && FlushThreadRunning)
{
FlushThreadRunning = false;
Platform::Thread_Wait(FlushThread);
Platform::Thread_Free(FlushThread);
}
}
void RequestFlush()
{
Platform::Mutex_Lock(SecondaryBufferLock);
printf("NDS SRAM: Flush requested\n");
memcpy(SecondaryBuffer, Buffer, Length);
FlushVersion++;
TimeAtLastFlushRequest = time(NULL);
Platform::Mutex_Unlock(SecondaryBufferLock);
}
void FlushThreadFunc()
{
for (;;)
{
Platform::Sleep(100 * 1000); // 100ms
if (!FlushThreadRunning) return;
// We debounce for two seconds after last flush request to ensure that writing has finished.
if (TimeAtLastFlushRequest == 0 || difftime(time(NULL), TimeAtLastFlushRequest) < 2)
{
continue;
}
FlushSecondaryBuffer();
}
}
void FlushSecondaryBuffer(u8* dst, s32 dstLength)
{
// When flushing to a file, there's no point in re-writing the exact same data.
if (!dst && !NeedsFlush()) return;
// When flushing to memory, we don't know if dst already has any data so we only check that we CAN flush.
if (dst && dstLength < SecondaryBufferLength) return;
Platform::Mutex_Lock(SecondaryBufferLock);
if (dst)
{
memcpy(dst, SecondaryBuffer, SecondaryBufferLength);
}
else
{
FILE* f = Platform::OpenFile(Path, "wb");
if (f)
{
printf("NDS SRAM: Written\n");
fwrite(SecondaryBuffer, SecondaryBufferLength, 1, f);
fclose(f);
}
}
PreviousFlushVersion = FlushVersion;
TimeAtLastFlushRequest = 0;
Platform::Mutex_Unlock(SecondaryBufferLock);
}
bool NeedsFlush()
{
return FlushVersion != PreviousFlushVersion;
}
void UpdateBuffer(u8* src, s32 srcLength)
{
if (!src || srcLength != Length) return;
// should we create a lock for the primary buffer? this method is not intended to be called from a secondary thread in the way Flush is
memcpy(Buffer, src, srcLength);
Platform::Mutex_Lock(SecondaryBufferLock);
memcpy(SecondaryBuffer, src, srcLength);
Platform::Mutex_Unlock(SecondaryBufferLock);
PreviousFlushVersion = FlushVersion;
}
}
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