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cc65/libsrc/cbm/rwcommon.s
cuz 544ff5b900 Working on the CBM file functions
git-svn-id: svn://svn.cc65.org/cc65/trunk@1533 b7a2c559-68d2-44c3-8de9-860c34a00d81
2002-11-17 22:45:55 +00:00

48 lines
1.0 KiB
ArmAsm

;
; Ullrich von Bassewitz, 17.11.2002
;
; Common stuff for the read/write routines
;
.export rwcommon
.import popax
.importzp ptr1, ptr2, ptr3, tmp2
.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
jsr popax ; Get count
eor #$FF
sta ptr1
txa
eor #$FF
sta ptr1+1 ; Remember -count-1
jsr popax ; Get buf
sta ptr2
stx ptr2+1
lda #$00
sta ptr3
sta ptr3+1 ; Clear ptr3
jsr popax ; Get the handle
sta tmp2
cpx #$01
bcs inv
cmp #MAX_FDS
inv: rts
.endproc