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cc65/libsrc/common/_sys.s
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73 lines
828 B
ArmAsm

;
; void __fastcall__ _sys (struct regs* r);
;
; Ullrich von Bassewitz, 16.12.1998
;
.export __sys
.import jmpvec
.importzp ptr1
__sys: sta ptr1
stx ptr1+1 ; Save the pointer to r
; Fetch the PC and store it into the jump vector
ldy #5
lda (ptr1),y
sta jmpvec+2
dey
lda (ptr1),y
sta jmpvec+1
; Get the flags, mask unnecessary bits and push them. Push a
dey
lda (ptr1),y
and #%11001011
pha
ldy #0
lda (ptr1),y
pha
; Get and assign X and Y
iny
lda (ptr1),y
tay
iny
lda (ptr1),y
tay
; Set a and the flags, call the machine code routine
pla
plp
jsr jmpvec
; Back from the routine. Save the flags and a
php
pha
; Put the register values into the regs structure
tya
ldy #2
sta (ptr1),y
dey
txa
sta (ptr1),y
dey
pla
sta (ptr1),y
ldy #3
pla
sta (ptr1),y
; Done
rts