Calling C function from asm prog

Which compiler are you using?

NC100 compiler with HEW IDE

That makes sense - some assemblers require symbol references, some don't, and some have options to ignore undefined symbols.  One could also potentially get the C-compiler to generate such a reference by doing something like this:

extern int pff; int GetPFF(void) { return pff; }

Thanks NGE, you were right !

I did have a '.glb' declaration but I forgot the underscore character (shame on me...)

Now the compilation process is completed without any error (see below)

assembler processing now

C:\0DATA\32C\32C Projects\R32C_GFORCE_GRAPHIC\R32C_GFORCE_3\main.a30
R32C/100 Series Assembler system V.1.02.01
Copyright (C) 2006 (2007 - 2010) Renesas Electronics Corporation.
and Renesas Solutions Corporation. All rights reserved.
macro processing now
assembler processing now
----*----*----*----*----*----*----*----*----*----*----
TOTAL ERROR(S) 00000
TOTAL WARNING(S) 00000
TOTAL LINE(S) 05416 LINES
CODE 00000629(000275H) program
( C:\0DATA\32C\32C Projects\R32C_GFORCE_GRAPHIC\R32C_GFORCE_3\main.a30 )
----*----*--
Phase R32C/100 Assembler finished

But now linkage pass 2 is faulty, see result below:

Phase R32C/100 Linker starting

Linkage Editor (ln100) for R32C/100 Series V.1.02.00.001

Copyright (C) 2006 (2007 - 2010) Renesas Electronics Corporation.

and Renesas Solutions Corporation. All rights reserved.

SentinelRMS (C) 1989-2006 SafeNet, Inc. All rights reserved.

now processing pass 2

Projects\R32C_GFORCE_GRAPHIC\R32C_GFORCE_3\Debug\main.r30"

C:\0DATA\32C\32C Projects\R32C_GFORCE_GRAPHIC\R32C_GFORCE_3\main.a30(461) : '_pff' value is undefined

Any clue ?

I dived in an old project with a R32C/111 where in the C file I have the following:

void initSystem(void);

void initSystem(void){

}

The declaration of the function can also done in an include. Maybe this declaration is needed for the linker.

And in the assembly:

.glb		_initSystem
jsr.a		_initSystem

It's now working fine !

I used the following:

jsr _pff to call a simple C function and

jsr $open when parameters have to be transmitted

Many thanks NGE for your kind help !!

Following successfully calling C functions from asm, I am now facing a new issue:

My data are defined as follows in asm project

;********************************************************
; RAM area allocation
;********************************************************

.section data_SB8, data

record_size: .blkl 1

but I don't know how to include variable and structure defined in C language functions to my data section

defined in asm

Here is an example of a structure defined in H file

/* Directory object structure */

typedef struct {
WORD index; /* Current read/write index number */
BYTE* fn; /* Pointer to the SFN (in/out) {file[8],ext[3],status[1]} */
CLUST sclust; /* Table start cluster (0:Static table) */
CLUST clust; /* Current cluster */
DWORD sect; /* Current sector */
} DIR;

and variable defined in C file like:

BYTE i, c;

Thks for your help

There is no good way to define a c structure in asm. You can manually define offsets in asm for the variables in the c structure. But when you change the structure you need to redefine your asm offsets.

A better way to use c structures in asm is to make use of the asm function also known as inline assembly. With this you can imbed asm in a c function. A small example from the NC100 compiler manual (chapter B2):

void func(void) 
{ 
    short idata; 
    short a[3]; 
    struct TAG{ 
        short i; 
        short k; 
    } s; 
    : 
    asm(" MOV.W R0, $$[FB]", idata); 
    : 
    asm(" MOV.W R0, $$[FB]", a[2]); 
    : 
    asm(" MOV.W R0, $$[FB]", s.i); 
    (Remainder omitted) 
    : 
    asm(" MOV.W $$[FB], $$[FB]", s.i, a[2]); 
}

And:

short idata; 
short a[3]; 
struct TAG{ 
    short i; 
    short k; 
} s; 
void func(void) 
{ 
    : 
    asm(" MOV.W R0, $$", idata); 
    : 
    asm(" MOV.W R0, $$", a[2]); 
    : 
    asm(" MOV.W R0, $$", s.i); 
    (remainder omitted) 
    : 
} 

Thks NGE for your quick answer but my purpose is to call C from asm and not the opposite.

My main project is in assembly and I just wanted to access a driver for sd card written in C

The question is how to define an @ in RAM for the C structure not to define it in asm

I would approach this by having the C-code do all structure references using function calls from the assembly side read / write individual structure data:

struct {
    int Member1;
    int Member2;
    int Member3:
} Struct;

int Get1(void) { return Struct.Member1; }
int Get2(void) { return Struct.Member2; }
int Get3(void) { return Struct.Member3; }
void Put1(int Arg) { Struct.Member1 = Arg: }
void Put2(int Arg) { Struct.Member2 = Arg; }
void Put3(int Arg) { Struct Member3 = Arg: }

I do not understand: where are the function calls from the assembly side read / write individual structure data in your example ?

From assembly when you need to access the structure from the C-code, call the "Get" for a read and "Put" for a write.

From assembly when you need to access the structure from the C-code, call the "Get" for a read and "Put" for a write.