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[UDFS] Remove legacy x86 asm string-length paths in favor of shared C/C++ implementation #277

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[UDFS] Remove legacy x86 asm string-length paths in favor of shared C/C++ implementation #277

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b9d68f3
refactoring
assorted Nov 1, 2025
a3a7243
try-fix-write
assorted Dec 25, 2025
cffe655
refactoring
assorted Feb 2, 2026
a3305a9
UDFInsertPrefix
assorted Feb 14, 2026
b1c40c0
Initial plan
Copilot Apr 19, 2026
e1ee3b3
[UDFS] remove legacy x86 asm string-length micro-optimizations
Copilot Apr 19, 2026
6614940
[UDFS] Remove all inline assembly from the driver
Copilot Apr 19, 2026
66f773c
fix: address review feedback - volatile touch reads, USHORT wraparoun…
Copilot Apr 19, 2026
a68deb7
fix: correct USHORT cast precedence in MaximumLength assignments
Copilot Apr 19, 2026
991f517
Merge branch 'udf-dev' of https://github.com/zero3k20/reactos into ud…
Zero3K20 Apr 27, 2026
4059a00
Merge origin/udf-dev into copilot/udfs-compare-assembly-c-code-perfor…
Copilot Apr 27, 2026
980106d
rebase: add trailing newline (sync tree state with rebased branch)
Copilot Apr 28, 2026
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17 changes: 2 additions & 15 deletions drivers/filesystems/udfs/Include/mem_tools.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -6,25 +6,12 @@

#ifdef MY_USE_INTERNAL_MEMMANAGER

#ifdef _X86_

__inline VOID DbgTouch(IN PVOID addr)
{
__asm {
mov eax,addr
mov al,[byte ptr eax]
}
}

#else // NO X86 optimization , use generic C/C++

__inline VOID DbgTouch(IN PVOID addr)
{
UCHAR a = ((PUCHAR)addr)[0];
volatile UCHAR a = ((volatile UCHAR*)addr)[0];
(void)a;
}

#endif // _X86_

//MEM_ALLOC_DESC Allocs[MY_HEAP_MAX_BLOCKS];

MEM_FRAME_ALLOC_DESC FrameList[MY_HEAP_MAX_FRAMES];
Expand Down
8 changes: 4 additions & 4 deletions drivers/filesystems/udfs/Include/mem_tools.h
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Original file line number Diff line number Diff line change
Expand Up @@ -198,13 +198,13 @@ VOID inline MyFreePool__(PVOID addr) {
// ULONG i;
newaddr = (PCHAR)addr;
if (!newaddr) {
__asm int 3;
__debugbreak();
return;
}
/*
for(i=0; i<MY_HEAP_ALIGN+1; i++) {
if (newaddr[len+i] != (UCHAR)('A'+i)) {
__asm int 3;
__debugbreak();
break;
}
}
Expand Down Expand Up @@ -233,7 +233,7 @@ ULONG inline MyReallocPool__(PCHAR addr, ULONG len, PCHAR *pnewaddr, ULONG newle

for(i=0; i<MY_HEAP_ALIGN+1; i++) {
if ((UCHAR)(addr[len+i]) != (UCHAR)('A'+i)) {
__asm int 3;
__debugbreak();
break;
}
}
Expand Down Expand Up @@ -269,7 +269,7 @@ ULONG inline MyReallocPool__(PCHAR addr, ULONG len, PCHAR *pnewaddr, ULONG newle
#ifdef MY_MEM_BOUNDS_CHECK
for(i=0; i<MY_HEAP_ALIGN+1; i++) {
if ((UCHAR)(newaddr[newlen+i]) != (UCHAR)('A'+i)) {
__asm int 3;
__debugbreak();
break;
}
}
Expand Down
55 changes: 8 additions & 47 deletions drivers/filesystems/udfs/Include/string_lib.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -65,34 +65,14 @@ RtlAppendUnicodeToString(
)
{
PWCHAR tmp;
USHORT i;

#ifdef _X86_

__asm push ebx
__asm push esi
__asm xor ebx,ebx
__asm mov esi,Str2
Scan_1:
__asm cmp [word ptr esi+ebx],0
__asm je EO_Scan
__asm add ebx,2
__asm jmp Scan_1
EO_Scan:
__asm mov i,bx
__asm pop esi
__asm pop ebx

#else // NO X86 optimization, use generic C/C++
ULONG i;

i=0;
while(Str2[i]) {
while(Str2[i] && i < (MAXUSHORT / sizeof(WCHAR))) {
i++;
}
i *= sizeof(WCHAR);

#endif // _X86_

tmp = Str1->Buffer;
ASSERT(Str1->MaximumLength);
if ((Str1->Length+i+sizeof(WCHAR)) > Str1->MaximumLength) {
Expand All @@ -102,13 +82,13 @@ RtlAppendUnicodeToString(
memcpy(tmp2, tmp, Str1->MaximumLength);
ExFreePool(tmp);
tmp = tmp2;
Str1->MaximumLength = STRING_BUFFER_ALIGN(i + sizeof(WCHAR))*2;
Str1->MaximumLength = (USHORT)(STRING_BUFFER_ALIGN(i + sizeof(WCHAR))*2);
Str1->Buffer = tmp;
}
RtlCopyMemory(((PCHAR)tmp)+Str1->Length, Str2, i);
i+=Str1->Length;
tmp[(i / sizeof(WCHAR))] = 0;
Str1->Length = i;
Str1->Length = (USHORT)i;

return STATUS_SUCCESS;

Expand All @@ -126,35 +106,16 @@ MyInitUnicodeString(
)
{

USHORT i;

#ifdef _X86_

__asm push ebx
__asm push esi
__asm xor ebx,ebx
__asm mov esi,Str2
Scan_1:
__asm cmp [word ptr esi+ebx],0
__asm je EO_Scan
__asm add ebx,2
__asm jmp Scan_1
EO_Scan:
__asm mov i,bx
__asm pop esi
__asm pop ebx

#else // NO X86 optimization, use generic C/C++
ULONG i;

i=0;
while(Str2[i]) {
while(Str2[i] && i < (MAXUSHORT / sizeof(WCHAR))) {
i++;
}
i *= sizeof(WCHAR);

#endif // _X86_

Str1->MaximumLength = STRING_BUFFER_ALIGN((Str1->Length = i) + sizeof(WCHAR));
Str1->Length = (USHORT)i;
Str1->MaximumLength = (USHORT)STRING_BUFFER_ALIGN(i + sizeof(WCHAR));
Str1->Buffer = (PWCHAR)MyAllocatePool__(NonPagedPool, Str1->MaximumLength);
if (!Str1->Buffer)
return STATUS_INSUFFICIENT_RESOURCES;
Expand Down
26 changes: 3 additions & 23 deletions drivers/filesystems/udfs/udf_dbg.h
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Expand Up @@ -120,13 +120,7 @@ DbgWaitForSingleObject_(

#ifdef UDF_DBG

#ifdef _X86_
// This is an illegal use of INT3
#define UDFBreakPoint() { __asm int 3 }
#else // _X86_

#define UDFBreakPoint() DbgBreakPoint()
#endif // _X86_
#define UDFBreakPoint() __debugbreak()

#ifdef BRUTE
#define BrutePoint() UDFBreakPoint()
Expand Down Expand Up @@ -189,26 +183,12 @@ VOID DebugFreePool(PVOID addr);
#define ValidateFileInfo(fi) {}
#endif

#if defined (_X86_) && defined (_MSC_VER)

__inline VOID UDFTouch(IN PVOID addr)
{
__asm {
mov eax,addr
mov al,[byte ptr eax]
}
}

#else // NO X86 optimization , use generic C/C++

__inline VOID UDFTouch(IN PVOID addr)
{
UCHAR a = ((PUCHAR)addr)[0];
a = a;
UCHAR a = *((volatile UCHAR*)addr);
UNREFERENCED_PARAMETER(a);
}

#endif // _X86_

#else // UDF_DBG

#define DbgAllocatePool(x,y) ExAllocatePoolWithTag(x,y,'Fnwd')
Expand Down