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cc65/libsrc/cbm/rwcommon.s
2018-05-22 11:25:26 +02:00

45 lines
1.1 KiB
ArmAsm

;
; Ullrich von Bassewitz, 17.11.2002
;
; Common stuff for the read/write routines
;
.export rwcommon
.import popax, popptr1
.importzp ptr1, ptr2, ptr3, tmp2
.include "errno.inc"
.include "filedes.inc"
;--------------------------------------------------------------------------
; rwcommon: Pop the parameters from stack, preprocess them and place them
; into zero page locations. Return carry set if the handle is invalid,
; return carry clear if it is ok. If the carry is clear, the handle is
; returned in A.
.proc rwcommon
eor #$FF
sta ptr2
txa
eor #$FF
sta ptr2+1 ; Remember -count-1
jsr popptr1 ; Get buf to ptr1, Y=0 by call
sty ptr3
sty ptr3+1 ; Clear ptr3
jsr popax ; Get the handle
cpx #$01
bcs @L9
cmp #MAX_FDS ; Set carry if fd too large
sta tmp2
@L9: rts ; Return with result in carry
.endproc