No XMM register changes

[Orzel94]

Hi
I have problem with XMM register. I can't change value inside them even by using MOSD or MOVLDP
I have code in C and in ASM which should do exactly the same (school project).

Could you help mi with it?

http://pastebin.com/q4Z9UzTD
http://pastebin.com/vHVp0RwE

[jj2007]

Hi Orzel,
1. your code assembles only if the last line is END aproxASM
2. then, it starts as follows:

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CPU Disasm
Address         Hex dump            Command                           Comments
<ModuleEntryPoi Ú$  55              push ebp
00401001        ³.  8BEC            mov ebp, esp
00401003        ³.  BB 00000000     mov ebx, 0
00401008        ³.  660F1265 28     movlpd xmm4, [ebp+28]
0040100D        ³.  660F1245 08     movlpd xmm0, [ebp+8]
00401012        ³.  660F124D 10     movlpd xmm1, [ebp+10]
... and all instructions work as expected. My advice: install Olly and debug your executable.

Welcome to the Forum :icon14:

[Orzel94]

thanks for answer
I'm using MS VS 2015 for dubbuging (Windows forms C# app with C++ & ASM .dll's)

When I add aproxASM at the end there is no changes, but when I replace my code with yours (don't know if I should actually) Ive got some errors

screenshots: https://1drv.ms/f/s!AhFXsdGfJyB21F2tZSEVSKwjDf_n

by the way: you mean

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MOV eax,ebx
ret
aproxASM endp
END aproxASM

or just

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MOV eax,ebx

END aproxASM

[jj2007]

What I showed you is the disassembly, not the source. I have used your source with one single change: the last line, which is END in your code, becomes END aproxASM

Thus, the assembler (MASM = ML.exe) knows that aproxASM is the entry point. I do not use Visual S. for assembly, it's an overkill, so I don't know what VS actually does under the hood. Try \masm32\qEditor.exe, it's a better tool.

[Orzel94]

When I've tried to assembly my code in QEditor I get "syntax error : xmm"

When I open .dll in Ollydbg the code is completly different...   https://1drv.ms/i/s!AhFXsdGfJyB21GAiSPipxuAKmU1o

[jj2007]

Mateusz,
You get the "syntax error : xmm" because Masm32 ships with a very old version of MASM. RichMasm would detect this and install automatically a new one when you hit F6, but with qEditor you will have to do it manually:
- download HJWasm32
- extract HJWasm32.exe to \Masm32\bin
- rename \Masm32\bin\ml.exe to mlv614.exe
- rename \Masm32\bin\HJWasm32.exe to ml.exe
- retry console assembly and link in qEditor

Btw you don't need screenshots to show disassemblies. Just select the lines in Olly that are interesting in Olly and hit CtrlC; then paste them here inside code tags (the # icon).

Btw in your screenshot, you show the point after LoadLibrary. The interesting part is when you call the address received by GetProcAddress.

[TWell]

tested with ml.exe 10

Code Select Expand

DllEntry proc
MOV EAX, 1
RET
DllEntry endp
...
...
END DllEntryor

Code Select Expand

_DllMainCRTStartup proc
MOV EAX, 1
RET
_DllMainCRTStartup endp
...
...
END _DllMainCRTStartupand use def-file for dlls.

[hutch--]

Just get a later version of ML.EXE.

[Orzel94]

debuging is ok now and it compiles to .exe but after "create new .dll" in qEditor a pasting my code (by replacing all) I get sth like that:

Code Select Expand

ASM.asm: 50 lines, 2 passes, 69 ms, 0 warnings, 0 errors
Microsoft (R) Incremental Linker Version 5.12.8078
Copyright (C) Microsoft Corp 1992-1998. All rights reserved.
ASM.def : error LNK2001: unresolved external symbol aproxASM
ASM.lib : fatal error LNK1120: 1 unresolved externals
LINK : fatal error LNK1141: failure during build of exports file
Could Not Find C:\Users\Mateusz\Documents\Visual Studio 2015\Projects\Generator fraktali 2D\ASM\masmdll\ASM.exp
Volume in drive C is OS
Volume Serial Number is 8482-C98C

Directory of C:\Users\Mateusz\Documents\Visual Studio 2015\Projects\Generator fraktali 2D\ASM\masmdll

21.01.2017  10:34             1 662 ASM.asm
21.01.2017  10:36                31 ASM.def
               2 File(s)          1 693 bytes
               0 Dir(s)  35 056 488 448 bytes free

ASM.def is:

Code Select Expand

LIBRARY ASM
EXPORTS aproxASM


[TWell]

Code Select Expand

LIBRARY ASM
EXPORTS aproxASM=_aproxASM@40

[Orzel94]

Code Select Expand

Creating library ASM.lib and object ASM.exp
ASM.exp : error LNK2001: unresolved external symbol _aproxASM@40
ASM.dll : fatal error LNK1120: 1 unresolved externals

[jj2007]

Your ASM.def file is OK. I would choose another file name, though ;-)

The normal structure of a DLL source is like this:

Code Select Expand

.code
LibMain proc instance:DWORD, reason:DWORD, unused:DWORD
  mov eax, 1
  ret
LibMain endp

aproxASM proc p_real: REAL8, p_imaginary: REAL8, c_real:REAL8, c_imaginary:REAL8, four:REAL8
MOV ebx,0
...
ret
aproxASM endp

end LibMain

[Orzel94]

its ok know, I have some errors (exception at the exit of procedure) but I hope (or not XD) it's logic issue (I don't know yet :/ )

last thing to make sure
1) to return integer value i must put it into EAX? Is this enought or shall I do sth more with it?
2)to load library from C# app I need

Code Select Expand

[DllImport("ASM.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.Cdecl)]
        static extern int aproxASM(double p_real, double p_imaginary, double c_real, double c_imaginary, double four);

or just

Code Select Expand

[DllImport("ASM.dll")]
        static extern int aproxASM(double p_real, double p_imaginary, double c_real, double c_imaginary, double four);


[TWell]

A small test:

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using System;
using System.Runtime.InteropServices;
// c:\Windows\Microsoft.NET\Framework\v2.0.50727\csc.exe aproxTestCc.cs /platform:x86
class aproxTestCs
{
[DllImport("aproxC.dll")]
static extern int aproxC(double p_real, double p_imaginary, double c_real, double c_imaginary);
[DllImport("aproxASM.dll")]
static extern int aproxASM(double p_real, double p_imaginary, double c_real, double c_imaginary, double four);

static void Main()
{
double p_real = -1.5;
double p_imaginary = -1.5;
double c_real = 0.65;
double c_imaginary = -0.03;
double four = 4.0;

int ac = aproxC(p_real, p_imaginary, c_real, c_imaginary);
Console.WriteLine("ac={0}", ac);
int aa = aproxASM(p_real, p_imaginary, c_real, c_imaginary, four);
Console.WriteLine("aa={0}", aa);
}
}C version works, but ASM version crash.

But this outputs
ac=1
aa=360

Code Select Expand

#include <stdio.h>

int __stdcall aproxC(double p_real, double p_imaginary, double c_real, double c_imaginary);
#pragma comment(lib, "aproxC.lib")
int __stdcall aproxASM(double p_real, double p_imaginary, double c_real, double c_imaginary, double four);
#pragma comment(lib, "aproxASM.lib")

int __cdecl main(void)
{
double p_real = -1.5;
double p_imaginary = -1.5;
double c_real = 0.65;
double c_imaginary = -0.03;
double four = 4.0;

int ac = aproxC(p_real, p_imaginary, c_real, c_imaginary);
printf("ac=%d\n", ac);
int aa = aproxASM(p_real, p_imaginary, c_real, c_imaginary, four);
printf("aa=%d\n", aa);

return 0;
}BTW ebx is reserved register, use ecx instead or push/pop ebx

[Orzel94]

I changed to ECX, create project with your code and add .lib files by properties -> linker -> Additional Library Directories
and I got:

Code Select Expand

LNK2028 unresolved token (0A00003C) "int __stdcall aproxC(double,double,double,double)" (?aproxC@@$$FYGHNNNN@Z) referenced in function "int __cdecl main(void)" (?main@@$$HYAHXZ) test 2 C:\Users\Mateusz\documents\visual studio 2015\Projects\test 2\test 2\Source.obj 1
LNK2028 unresolved token (0A000045) "int __stdcall aproxASM(double,double,double,double,double)" (?aproxASM@@$$FYGHNNNNN@Z) referenced in function "int __cdecl main(void)" (?main@@$$HYAHXZ) test 2 C:\Users\Mateusz\documents\visual studio 2015\Projects\test 2\test 2\Source.obj 1
LNK2019 unresolved external symbol "int __stdcall aproxC(double,double,double,double)" (?aproxC@@$$FYGHNNNN@Z) referenced in function "int __cdecl main(void)" (?main@@$$HYAHXZ) test 2 C:\Users\Mateusz\documents\visual studio 2015\Projects\test 2\test 2\Source.obj 1
LNK2019 unresolved external symbol "int __stdcall aproxASM(double,double,double,double,double)" (?aproxASM@@$$FYGHNNNNN@Z) referenced in function "int __cdecl main(void)" (?main@@$$HYAHXZ) test 2 C:\Users\Mateusz\documents\visual studio 2015\Projects\test 2\test 2\Source.obj 1
LNK1120 4 unresolved externals test 2 C:\Users\Mateusz\documents\visual studio 2015\Projects\test 2\Debug\test 2.exe 1


edit: sory for such trivial (I think) things but it's my first touch to DLLs and Assembler (semester must be passed XD but its quite interesting)