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cc65/libsrc/common/sscanf.s
cuz 501cc4c6c8 Replace sscanf by an assembler version
git-svn-id: svn://svn.cc65.org/cc65/trunk@3314 b7a2c559-68d2-44c3-8de9-860c34a00d81
2004-11-28 18:23:16 +00:00

83 lines
1.7 KiB
ArmAsm

;
; 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