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cc65/libsrc/apple2/lseek.s

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2014-11-22 00:04:11 +00:00
;
; Peter Ferrie, 21.11.2014
;
; off_t __fastcall__ lseek(int fd, off_t offset, int whence);
;
.export _lseek
.import popax
.include "zeropage.inc"
.include "errno.inc"
.include "mli.inc"
.include "filedes.inc"
_lseek:
; Save whence
sta tmp1
stx tmp2
; Get and save offset
jsr popax
sta ptr1
stx ptr1+1
jsr popax
sta ptr2
; Get and process fd
jsr popax
jsr getfd ; Returns A, Y and C
bcs errno
; Check for device
cmp #$80
bcs einval
; Valid whence values are 0..2
ldx tmp2
bne einval
ldx tmp1
cpx #3
bcs einval
; Set fd
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sta mliparam + MLI::MARK::REF_NUM
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txa
beq cur
lda #GET_EOF_CALL
dex
beq end
; SEEK_SET
dex
txa
tay
beq seek_common
; SEEK_CUR
cur:
lda #GET_MARK_CALL
; SEEK_END
end:
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; MARK_COUNT must == EOF_COUNT, otherwise unexpected behaviour
.assert MARK_COUNT = EOF_COUNT, error
ldx #MARK_COUNT
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jsr callmli
bcs oserr
lda mliparam + MLI::MARK::POSITION
ldx mliparam + MLI::MARK::POSITION+1
ldy mliparam + MLI::MARK::POSITION+2
seek_common:
adc ptr1
sta mliparam + MLI::MARK::POSITION
txa
adc ptr1+1
sta mliparam + MLI::MARK::POSITION+1
tya
adc ptr2
sta mliparam + MLI::MARK::POSITION+2
; Set file pointer
lda #SET_MARK_CALL
ldx #MARK_COUNT
jsr callmli
bcs oserr
rts
; Load errno code
einval: lda #EINVAL
; Set __errno
errno: jmp __directerrno
; Set __oserror
oserr: jmp __mappederrno