cc65/libsrc/common/fscanf.s

82 lines
1.9 KiB
ArmAsm

;
; int fscanf (FILE* f, const char* format, ...);
;
; Ullrich von Bassewitz, 2004-11-28
;
.export _fscanf
.import addysp, decsp4, _vfscanf
.importzp sp, ptr1
.macpack generic
; ----------------------------------------------------------------------------
; Data
.bss
ParamSize: .res 1 ; Number of parameter bytes
; ----------------------------------------------------------------------------
; int fscanf (FILE* f, const char* format, ...)
; /* Standard C function */
; {
; va_list ap;
;
; /* Setup for variable arguments */
; va_start (ap, format);
;
; /* Call vfscanf(). Since we know that va_end won't do anything, we will
; ** save the call and return the value directly.
; */
; return vfscanf (f, format, ap);
; }
;
.code
_fscanf:
sty ParamSize ; Number of param bytes passed in Y
; We have to push f 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 Format argument
lda ParamSize
add sp
sta ptr1
ldx sp+1
bcc @L1
inx
@L1: stx ptr1+1
; Now copy both, f and format
ldy #4-1
@L2: lda (ptr1),y
sta (sp),y
dey
bpl @L2
; Load va_list (last and __fastcall__ parameter to vfscanf)
lda ptr1
ldx ptr1+1
; Call vfscanf
jsr _vfscanf
; Cleanup the stack. We will return what we got from vfscanf
ldy ParamSize
jmp addysp