asmcode->c-fkt

Hello
I have this code:

Code:

proc	_gegeben1_171202asm
;Dies ist die gegebene ASM Prozedur fuer die 1.Aufgabe im Modul 1A171202.C.
;Dort ist der C   Aufruf dieser gegebenen ASM Prozedur zu programmieren.
;Die Prozedur hat einen Rueckgabewert.
push bp
mov	 bp,sp
push di
	mov	al,[bp+6]	;signed char
	cbw			;ax=signed int
	cwd			;dx,ax=signed long int

	push	ax
	call	[word ptr bp+8]
	add	sp,2

	mov  di,[bp+4]
	fstp [qword ptr di]     ;store and pop
pop	di
mov	sp,bp
pop	bp
ret
endp	_gegeben1_171202asm

I have to program a call in c of this asm-code.
The solution is:

Code:

//variables i have got
signed char s_c1;
double d1;
(*proz)(int)
signed long int s_l1;

//call
s_l1 = gegeben1_171202asm (&d1,s_c1,proz);

I unterstand the order of the parameters, s_c1 and proz, but i don`t understand, why i have a "*d1" instead of "d1" and why the surrender value is from type "long int" instead of "double"(qword is the lenght of a double)
I hope somebody can helps me.

many thanks in advance.

regards
sphreak

today, i got the explanation.
if somebody is interest in that:
1) i can only intepret the surrender value. In this example you can read it by this line: "cwd ;dx,ax=signed long int"
2) double has a length of two words. a pointer has a length of one word.
my mistake: i thought that my double is from bp+2 up to bp+6. but thats wrong. bp+4 means from bp+2 up to bp+4 (one word). because of fstp(it`s only for double and float) and qword(length of double) it`s a pointer of a double

regards