hello friends,
i want to use c function in my assembly program,after reading keil c51 user i came to know about calling conventions
used to interface c and assembly but i am unable to do it properly due to some doubts can please clearify it to me.

i have assembled following c file to src

#pragma SRC
#pragma SMALL
#pragma NOREGPARMS
int function(int v_a, char v_b, bit v_c,long v_d,bit v_e)
{
v_d=v_a+v_b;
}


below is the src file


; .\CSAMPLE1.SRC generated from: .\CSAMPLE1.C


NAME CSAMPLE1

?PR?function?CSAMPLE1 SEGMENT CODE
?DT?function?CSAMPLE1 SEGMENT DATA OVERLAYABLE
?BI?function?CSAMPLE1 SEGMENT BIT OVERLAYABLE
PUBLIC ?function?BIT
PUBLIC ?function?BYTE
PUBLIC function

RSEG ?DT?function?CSAMPLE1
?function?BYTE:
v_a?040: DS 2
v_b?041: DS 1
v_d?043: DS 4

RSEG ?BI?function?CSAMPLE1
?function?BIT:
v_c?042: DBIT 1
v_e?044: DBIT 1
; /*------------------------------------------------------------------------------
; CSAMPLE1.C
;
; Copyright 1995-1999 Keil Software, Inc.
; ------------------------------------------------------------------------------*/
;
;
; #pragma SRC
; #pragma SMALL
; #pragma NOREGPARMS
; //unsigned int asmfunc1(unsigned int arg);
; int function(int v_a, char v_b, bit v_c,long v_d,bit v_e)

RSEG ?PR?function?CSAMPLE1
USING 0
function:
; SOURCE LINE # 12
; {
; SOURCE LINE # 13
; v_d=v_a+v_b;
; SOURCE LINE # 14
MOV R7,v_b?041
MOV A,R7
RLC A
SUBB A,ACC
MOV R6,A
MOV A,v_a?040+01H
ADD A,R7
MOV R7,A
MOV A,v_a?040
ADDC A,R6
MOV R6,A
RLC A
SUBB A,ACC
MOV v_d?043+03H,R7
MOV v_d?043+02H,R6
MOV v_d?043+01H,A
MOV v_d?043,A
; }
; SOURCE LINE # 15
RET
; END OF function

END


please tell me the meaning of following assembler output in above code
MOV R7,v_b?041
MOV v_d?043+03H,R7
MOV v_d?043+02H,R6
MOV v_d?043+01H,A
MOV v_d?043,A
what are these numbers 40,41,43?

folowing is the code used to call function "function" from assembly but it gives error of undefined varibales

EXTRN CODE (function)
EXTRN DATA (?function?BYTE)
EXTRN BIT (?function?BIT)

MOV R6,#HIGH intval
MOV R7,#LOW intval
MOV R7,#charconst
SETB ?function?BIT+0
MOV ?function?BYTE+3,longval+0
MOV ?function?BYTE+4,longval+1
MOV ?function?BYTE+5,longval+2
MOV ?function?BYTE+6,longval+3
MOV C,bitvalue
MOV ?function?BIT+1,C
LCALL function
MOV intresult+0,R6
MOV intresult+1,R7

thanks
kuldeep