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linux munmap: fix comment and simplify memory free. (PR #1293)

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Andrea 2024-04-26 21:53:09 +01:00 committed by GitHub
parent 664d7c2d86
commit c0bfb0b0fe
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1 changed files with 16 additions and 16 deletions
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32
source/Memory.cpp
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@ -243,6 +243,7 @@ static LPBYTE RWpages[kMaxExMemoryBanks]; // pointers to RW memory banks
static const UINT kNumAnnunciators = 4; static const UINT kNumAnnunciators = 4;
static bool g_Annunciator[kNumAnnunciators] = {}; static bool g_Annunciator[kNumAnnunciators] = {};
static const UINT num64KPages = 2; // number of 64K pages used to create hardware circular buffer
#ifdef _MSC_VER #ifdef _MSC_VER
static HANDLE g_hMemImage = NULL; // NB. When not initialised, this handle is NULL (not INVALID_HANDLE_VALUE) static HANDLE g_hMemImage = NULL; // NB. When not initialised, this handle is NULL (not INVALID_HANDLE_VALUE)
#else #else
@ -1522,7 +1523,6 @@ static void FreeMemImage(void)
#ifdef _MSC_VER #ifdef _MSC_VER
if (g_hMemImage) if (g_hMemImage)
{ {
const UINT num64KPages = 2;
for (UINT i = 0; i < num64KPages; i++) for (UINT i = 0; i < num64KPages; i++)
UnmapViewOfFile(memimage + i * _6502_MEM_LEN); UnmapViewOfFile(memimage + i * _6502_MEM_LEN);
@ -1536,13 +1536,8 @@ static void FreeMemImage(void)
#else #else
if (g_hMemTempFile) if (g_hMemTempFile)
{ {
const UINT num64KPages = 2; // unmap the whole region, everything inside will be unmapped too
for (UINT i = 0; i < num64KPages; i++) munmap(memimage, num64KPages * _6502_MEM_LEN);
{
munmap(memimage + i * _6502_MEM_LEN, _6502_MEM_LEN);
}
// with the following line, SDL_Quit() segfaults ????
// munmap(memimage + num64KPages * _6502_MEM_LEN, _6502_MEM_LEN);
fclose(g_hMemTempFile); fclose(g_hMemTempFile);
g_hMemTempFile = NULL; g_hMemTempFile = NULL;
@ -1572,8 +1567,7 @@ static LPBYTE AllocMemImage(void)
do do
{ {
res = false; res = false;
const UINT num64KRegions = 2; const SIZE_T totalVirtualSize = _6502_MEM_LEN * num64KPages;
const SIZE_T totalVirtualSize = _6502_MEM_LEN * num64KRegions;
baseAddr = (LPBYTE)VirtualAlloc(0, totalVirtualSize, MEM_RESERVE, PAGE_NOACCESS); baseAddr = (LPBYTE)VirtualAlloc(0, totalVirtualSize, MEM_RESERVE, PAGE_NOACCESS);
if (baseAddr == NULL) if (baseAddr == NULL)
break; break;
@ -1586,7 +1580,7 @@ static LPBYTE AllocMemImage(void)
break; break;
UINT count = 0; UINT count = 0;
while (count < num64KRegions) while (count < num64KPages)
{ {
// MSDN: "To specify a suggested base address for the view, use the MapViewOfFileEx function. However, this practice is not recommended." // MSDN: "To specify a suggested base address for the view, use the MapViewOfFileEx function. However, this practice is not recommended."
// The OS (ie. another process) may've beaten us to this suggested baseAddr. This is why we retry multiple times. // The OS (ie. another process) may've beaten us to this suggested baseAddr. This is why we retry multiple times.
@ -1595,7 +1589,7 @@ static LPBYTE AllocMemImage(void)
count++; count++;
} }
res = (count == num64KRegions); res = (count == num64KPages);
if (res) if (res)
break; break;
@ -1633,18 +1627,24 @@ static LPBYTE AllocMemImage(void)
const int fd = fileno(g_hMemTempFile); const int fd = fileno(g_hMemTempFile);
if (!ftruncate(fd, _6502_MEM_LEN)) if (!ftruncate(fd, _6502_MEM_LEN))
{ {
const UINT num64KPages = 2;
LPBYTE baseAddr = static_cast<LPBYTE>(mmap(NULL, num64KPages * _6502_MEM_LEN, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0)); LPBYTE baseAddr = static_cast<LPBYTE>(mmap(NULL, num64KPages * _6502_MEM_LEN, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0));
if (baseAddr) if (baseAddr)
{ {
bool ok = true;
for (UINT i = 0; i < num64KPages; i++) for (UINT i = 0; i < num64KPages; i++)
{ {
// can this ever fail? void * target = baseAddr + i * _6502_MEM_LEN;
mmap(baseAddr + i * _6502_MEM_LEN , _6502_MEM_LEN, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_FIXED, fd, 0); void * addr = mmap(target, _6502_MEM_LEN, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_FIXED, fd, 0);
ok = ok && (target == addr);
} }
// we could fclose the file here // we could fclose the file here
// but we keep it as a reminder of how to free the memory later // but we keep it as a reminder of how to free the memory later
return baseAddr; if (ok)
{
return baseAddr;
}
// revert to ALIGNED_ALLOC
munmap(baseAddr, num64KPages * _6502_MEM_LEN);
} }
} }