Convert ASM to MASM

[giraffe393]

Hey, could someone help me convert this inline ASM code to MASM ? I am not that good at it so it would help a lot. I have been trying and searching on Google but nothing can help me do it. Thanks you.

__asm
{
     mov rcx, [VarOne]
     mov rdx, [VarTwo]
     mov rax, [VarThree]
     call[VarFour]
     mov[VarFive], rax
}

VarOne = UINT64
VarTwo = UINT64
VarThree = DWORD64
VarFour = const BYTE*
VarFive = DWORD64

[Mikl__]

Code Select Expand

     mov rcx,VarOne
     mov rdx,VarTwo
     mov rax,VarThree
     call   VarFour
     mov VarFive, rax

[giraffe393]

Thanks ! But I don't understand how to do the parameters. It's like this :

Code Select Expand


.code

PROC func ???
     mov rcx,VarOne
     mov rdx,VarTwo
     mov rax,VarThree
     call   VarFour
     mov VarFive, rax
ENDP

END


[giraffe393]

I have got this:

Code Select Expand


.code

myfunc PROC varone:UINT64, vartwo:UINT64, varthree:DWORD64, varfour:const BYTE*, varfive:DWORD64
mov rcx, varone
mov rdx, vartwo
mov rax, varthree
call varfour
mov varfive, rax
myfunc ENDP
END


I get syntax error : byte on line 3 and unmatched block nesting : myfunc on line 9

[TimoVJL]

Code Select Expand

myfunc PROC varone:QWORD, vartwo:QWORD, varthree:QWORD, varfour:PTR, varfive:QWORD


[aw27]

@giraffe,
Things do not work like that. You must read an introductory text first.
Try this:
https://software.intel.com/en-us/articles/introduction-to-x64-assembly

[hutch--]

No RET in source.

[Mikl__]

Code Select Expand

.code
myfunc PROC varone:QWORD, vartwo:QWORD, varthree:QWORD
local varfive:QWORD

mov varone,rcx
mov vartwo,rdx
mov varthree,r8
call varfour
mov rax,varfive
        leave
        retn
myfunc endp

[aw27]

MASM makes an RBP stack frame whenever there are either LOCAL variables or function arguments. When it does that it will automatically insert LEAVE at the end of the function before a RET.

This means that:

Code Select Expand


myFunc2 proc varOne:qword, varTwo:qword
ret
myFunc2 endp

myFunc1 proc varOne:qword, varTwo:qword, varThree:qword, varFour:ptr, varFive:qword
mov varOne, rcx
mov varTwo, rdx
mov varThree, r8
mov varFour, r9
sub rsp, 20h
call r9
mov rax, varFive
ret
myFunc1 endp


will be coded as:

Code Select Expand


00000000 myFunc2 proc varOne:qword, varTwo:qword
00000000  55    *     push   rbp
00000001  48/ 8B EC    *     mov    rbp, rsp
ret
00000004  C9    *     leave 
00000005  C3    *     ret    00000h
00000006 myFunc2 endp

00000006 myFunc1 proc varOne:qword, varTwo:qword, varThree:qword, varFour:ptr, varFive:qword
00000006  55    *     push   rbp
00000007  48/ 8B EC    *     mov    rbp, rsp
0000000A  48/ 89 4D 10 mov varOne, rcx
0000000E  48/ 89 55 18 mov varTwo, rdx
00000012  4C/ 89 45 20 mov varThree, r8
00000016  4C/ 89 4D 28 mov varFour, r9
0000001A  48/ 83 EC 20 sub rsp, 20h
0000001E  41/ FF D1 call r9
00000021  48/ 8B 45 30 mov rax, varFive
ret
00000025  C9    *     leave 
00000026  C3    *     ret    00000h
00000027 myFunc1 endp


Instructions with an asterisc are produced by the MASM engine by its own initiative.