[RESOLVED] File Extension ".S"

[John E]

I'm trying to build a 64-bit library called libffi using MSVC. It contains a bunch of 'C' files and another file with the extension .S whose file contents seem to be mostly assembler - but with certain 'C' traits, such as #defines / #includes etc. The file contents look something like this:-

#define LIBFFI_ASM
#include <fficonfig.h>
#include <ffi.h>
	
/* Constants for ffi_call_win64 */	
#define STACK 0
#define PREP_ARGS_FN 32
#define ECIF 40
#define CIF_BYTES 48
#define CIF_FLAGS 56
#define RVALUE 64
#define FN 72

/* ffi_call_win64 (void (*prep_args_fn)(char *, extended_cif *),
                   extended_cif *ecif, unsigned bytes, unsigned flags,
                   unsigned *rvalue, void (*fn)());
 */

#ifdef _MSC_VER
PUBLIC	ffi_call_win64

EXTRN	__chkstk:NEAR
EXTRN	ffi_closure_win64_inner:NEAR

_TEXT	SEGMENT

;;; ffi_closure_win64 will be called with these registers set:
;;;    rax points to 'closure'
;;;    r11 contains a bit mask that specifies which of the
;;;    first four parameters are float or double
;;;
;;; It must move the parameters passed in registers to their stack location,
;;; call ffi_closure_win64_inner for the actual work, then return the result.
;;; 
ffi_closure_win64 PROC FRAME
	;; copy register arguments onto stack
	test	r11, 1
	jne	first_is_float	
	mov	QWORD PTR [rsp+8], rcx
	jmp	second
first_is_float:
	movlpd	QWORD PTR [rsp+8], xmm0

second:
	test	r11, 2
	jne	second_is_float	
	mov	QWORD PTR [rsp+16], rdx
	jmp	third
second_is_float:
	movlpd	QWORD PTR [rsp+16], xmm1

third:
	test	r11, 4
	jne	third_is_float	
	mov	QWORD PTR [rsp+24], r8
	jmp	fourth
third_is_float:
	movlpd	QWORD PTR [rsp+24], xmm2

// tons of other stuff

#endif

As you can see, the presence of #ifdef _MSC_VER creates the impression that it should be buildable with MSVC - but if I add it to a VS2015 project, VS2015 doesn't even seem to recognise it (clicking 'Properties' for the file simply says Does not participate in build).

I tried changing the file extension to .c but that didn't help either. I just got loads of compiler errors - starting with error C2061: syntax error: identifier 'ffi_call_win64' which occurs at the line I've indicated in blue.

What am I doing wrong

[Edit...] I think I'm starting to understand what's wrong... where I see the text:- Does not participate in build, I realised later that it's an entry in a drop-down list. If I go back to my previous compiler (VS2005) the relevant entry in that list box says:- Microsoft Macro Assembler. However, that option isn't present with VS2015 (Community Edition). Is the Macro Assembler an additional tool that I need to install separately? Or is assembly language just not supported in the Community Edition?

[Richard.J]

Does this link help?
https://msdn.microsoft.com/de-de/library/afzk3475.aspx

[2kaud]

Is the Macro Assembler an additional tool that I need to install separately? Or is assembly language just not supported in the Community Edition?

The macro assembler is part of VS2015 community and is installed. To find it from a command line prompt

cd \
dir ml*.exe /s/a/o/p

ml.exe is the 32 bit assembler
ml64.exe is the 64 bit assembler

[John E]

Thanks guys,

ml64.exe is pre-installed but it's in 2 x folders:- VC\bin\amd64 and \VC\bin\x86_amd64 (whereas my CPU is an Intel).

So as an experiment I decided to surround all the assembler with __asm{} and build as a 'C' file. But when I tried that, it gave me:- error C4235: nonstandard extension used: '__asm' keyword not supported on this architecture

I'm a bit baffled at the moment...

[2kaud]

In-line assembler is not support for 64bit

[John E]

In-line assembler is not support for 64bit

Okay, that explains one problem but I'm still puzzled about why I've no entry for Microsoft Macro Assembler.

2kaud - could you select a source file in your Solution Explorer and then select its Properties. Under General->Item Type can you see if any of the items refers to MASM? On my system it simply doesn't appear in the list of build tools.

ml64.exe is pre-installed but it's in 2 x folders:- VC\bin\amd64 and \VC\bin\x86_amd64 (whereas my CPU is an Intel)

Maybe I need to add those folders to my system path or something??

[2kaud]

could you select a source file in your Solution Explorer and then select its Properties. Under General->Item Type can you see if any of the items refers to MASM?

Nothing on my VS2015 either that refers to assembler.

[2kaud]

ml64.exe is pre-installed but it's in 2 x folders:- VC\bin\amd64 and \VC\bin\x86_amd64 (whereas my CPU is an Intel).

I think it's the amd64 one but I'm not an assembler expert. You might want to consider asking in the assembler forum?

[John E]

Will do, thanks.

[2kaud]

You might find this article and its links of help

https://social.msdn.microsoft.com/Fo...lstudiogeneral

[2kaud]

I think you need to specify a custom build for the .s files. See
https://msdn.microsoft.com/en-us/library/hefydhhy.aspx

You can then specify the required command line for ml64.exe to compile the .s file

PS Try renaming the .s file(s) to .asm as .asm is the extension for Microsoft assembler files.

[John E]

Actually I think I found it eventually...

1) Right click on the project file (in Solution Explorer)
2) Select Build Dependencies->Build Customizations
3) Tick the option for "masm"

Microsoft Macro Assembler will now be listed as one of the available build tools when you select Properties->General->Item Type for a given source file.

Not exactly intuitive - but it seems to be working...

[2kaud]

Yes, I agree not very intuitive. It uses ml or ml64 based upon what is specified as active in the configuration manager.

You can now alter the masm properties for the build similar to changing c++ build properties.