🚀 go-pugleaf

> I would also be tempted to turn off stack frames for this function.

In that case you would be jumping out of a plane without your parachute. 
Better to use
__declspec(naked)
and write every byte of the assembly code yourself.

>>void __fastcall GetCPUID_1(unsigned int cmd, TRegisters & regs)
>>  {
>>  _EBX = _ECX = _EDX = 0;
>
> Premature clearing of passed variables.
> _fastcall Order( EAX, EDX, ECX, SP[4], SP[8].... )
> ...
> EDI and EBX not preserved as required

Not so.

Compile the source from the command line with the -S option to see the 
generated code in a *.asm file.

SOP for since at least TC 2 is to push registers that are explicitly used. 
Between the possiblity of fancy code masking its detection and paranoia, it 
is an implicit requirement for a programmer to check the generated code for 
any source using inline assembly or pseudo-registers to insure that what is 
required has been saved and restored.

---------------------
 ; void __fastcall GetCPUID_1(unsigned int cmd, TRegisters & regs)
 ;
 push ebp
 mov ebp,esp
 push ecx
 push ebx
 push esi
 push edi
 mov esi,edx
 mov dword ptr [ebp-4],eax
 ;
 ;   {
 ;   _EBX = _ECX = _EDX = 0;
 ;

---------------------

>>    mov edi,esi /* _EDI = (unsigned long) & regs; */
>
> Same issues, plus new one:
> Where did esi come from?

GetCPUID_1's generated code shows esi contains &regs

---------------------
 ;   _EDI = reinterpret_cast<unsigned long>(& regs);
 ;
 ;
 mov edi,esi

---------------------

> Does the compiler "know" that you trounced edx (regs)?

It does not use the value so does not need to know.

.  Ed

> Bob Gonder wrote in message
> news:37l6a3dnmrn3m9blstu4dqvmmjah97nbif@4ax.com...
>
>>Either of these should be close.  I say 'close' because I have not tested
>
> Definately untested <G>
>
> I would also be tempted to turn off stack frames for this function.
>
>>void __fastcall GetCPUID_1(unsigned int cmd, TRegisters & regs)
>>  {
>>  _EBX = _ECX = _EDX = 0;
>
> Premature clearing of passed variables.
> _fastcall Order( EAX, EDX, ECX, SP[4], SP[8].... )
>
>>  _EDI = reinterpret_cast<unsigned long>(& regs);
>
> _EDI = _EDX
> EDI and EBX not preserved as required
> (unless compiler is doing hidden magic)
>
>>  _EAX = cmd;
>
> NOP, cmd is passed in eax
>
>>  __emit__(0x0F, 0xA2); // insert opcode for GetCpuId
>>  regs.EDX = _EDX;
>>  regs.ECX = _ECX;
>>  regs.EBX = _EBX;
>>  regs.EAX = _EAX;
>>  }
>>
>>void __fastcall GetCPUID_2(unsigned int cmd, TRegisters & regs)
>>  {
>>  __asm {
>>    xor edx,edx
>>    mov ebx,edx
>>    mov ecx,edx
>>    mov eax,[cmd]
>>    mov edi,esi /* _EDI = (unsigned long) & regs; */
>
> Same issues, plus new one:
> Where did esi come from?
>
>>    db 0FH, 0A2H /* opcode for GetCpuId */
>>    }
>>
>>  regs.EDX = _EDX;
>
> Does the compiler "know" that you trounced edx (regs)?
>
>>  regs.ECX = _ECX;
>>  regs.EBX = _EBX;
>>  regs.EAX = _EAX;
>>  }
>
>