cc65/libsrc/common/sscanf.s

;
; int sscanf (const char* str, const char* format, ...);
;
; Ullrich von Bassewitz, 2004-11-28
;

	.export	      	_sscanf
	.import		addysp, decsp4, _vsscanf
	.importzp	sp, ptr1

	.macpack     	generic

; ----------------------------------------------------------------------------
; Data

.bss

ParamSize: 	.res  	1 		; Number of parameter bytes

; ----------------------------------------------------------------------------
; Code
; int sscanf (const char* str, const char* format, ...)
; /* Standard C function */
; {
;     va_list ap;
;
;     /* Setup for variable arguments */
;     va_start (ap, format);
;
;     /* Call vsscanf(). Since we know that va_end won't do anything, we will
;      * save the call and return the value directly.
;      */
;     return vsscanf (str, format, ap);
; }
;

.code

_sscanf:
  	sty	ParamSize 		; Number of param bytes passed in Y

; We have to push buf and format, both in the order they already have on stack.
; To make this somewhat more efficient, we will create space on the stack and
; then do a copy of the complete block instead of pushing each parameter
; separately. Since the size of the arguments passed is the same as the size
; of the fixed arguments, this will allow us to calculate the pointer to the
; fixed size arguments easier (they're just ParamSize bytes away).

	jsr	decsp4

; Calculate a pointer to the fixed parameters

	lda	ParamSize
	add	sp
	sta	ptr1
	ldx	sp+1
	bcc	@L1
	inx
@L1:	stx	ptr1+1

; Now copy both, str and format

	ldy	#4-1
@L2:	lda	(ptr1),y
	sta	(sp),y
	dey
	bpl	@L2

; Load va_list (last and __fastcall__ parameter to vsscanf)

 	lda    	ptr1
 	ldx    	ptr1+1

; Call vsscanf

	jsr   	_vsscanf

; Cleanup the stack. We will return what we got from vsscanf

	ldy	ParamSize
	jmp	addysp