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cc65/libsrc/atari/open.s
cpg 62d883157a added support for fd indirection
git-svn-id: svn://svn.cc65.org/cc65/trunk@9 b7a2c559-68d2-44c3-8de9-860c34a00d81
2000-05-28 21:51:06 +00:00

211 lines
3.6 KiB
ArmAsm

;
; Christian Groessler, May-2000
;
; int open(const char *name,int flags,...);
;
UCASE_FILENAME = 1 ; comment it out if filename shouldn't be uppercased
.include "atari.inc"
.include "../common/fmode.inc"
.include "../common/errno.inc"
.export _open
.import fddecusage,newfd
.import __do_oserror,__seterrno,incsp4
.import ldaxysp,addysp,subysp
.import _strupr,__oserror
.importzp tmp4,tmp2,sp
.ifdef UCASE_FILENAME
.importzp tmp3,ptr4
.endif
.proc _open
cpy #4 ; correct # of arguments (bytes)?
beq parmok ; parameter count ok
tya ; parm count < 4 shouldn't be needed to be checked
sec ; (it generates a c compiler warning)
sbc #4
tay
jsr addysp ; fix stack, throw away unused parameters
parmok: jsr findfreeiocb
beq iocbok ; we found one
lda #<EMFILE ; "too many open files"
ldx #>EMFILE
seterr: jsr __seterrno
jsr incsp4 ; clean up stack
lda #$FF
tax
rts ; return -1
; process the mode argument
; @@@TODO: append not handled yet!
iocbok: stx tmp4
jsr clriocb ; init with zero
ldy #1
jsr ldaxysp ; get mode
ldx tmp4
cmp #O_RDONLY
bne l1
lda #OPNIN
set: sta ICAX1,x
bne cont
l1: cmp #O_WRONLY
bne l2
lda #OPNOT
bne set
l2: ; O_RDWR
lda #OPNOT|OPNIN
bne set
; process the filename argument
cont: ldy #3
jsr ldaxysp
.ifdef UCASE_FILENAME
; we make sure that the filename doesn't contain lowercase letters
; we copy the filename we got onto the stack, uppercase it and use this
; one to open the iocb
; we're using tmp3, ptr4
; save the original pointer
sta ptr4
stx ptr4+1
; now we need the length of the name
ldy #0
loop: lda (ptr4),y
beq str_end
cmp #ATEOL ; we also accept Atari EOF char as end of string
beq str_end
iny
bne loop ; not longer than 255 chars (127 real limit)
toolong:lda #<EINVAL ; file name is too long
ldx #>EINVAL
jmp seterr
str_end:iny ; room for terminating zero
cpy #128 ; we only can handle lenght < 128
bcs toolong
sty tmp3 ; save size
jsr subysp ; make room on the stack
; copy filename to the temp. place on the stack
lda #0 ; end-of-string
sta (sp),y ; Y still contains length + 1
dey
loop2: lda (ptr4),y
sta (sp),y
dey
bpl loop2 ; bpl: this way we only support a max. length of 127
; uppercase the temp. filename
ldx sp+1
lda sp
jsr _strupr
; leave X and Y pointing to the modified filename
lda sp
ldx sp+1
.endif ; defined UCASE_FILENAME
ldy tmp4
;AX - points to filename
;Y - iocb to use, if open needed
jsr newfd ; maybe we don't need to open and can reuse an iocb
; returns fd num to use in tmp2, all regs unchanged
bcs doopen ; C set: open needed
lda #0 ; clears N flag
beq finish
doopen: sta ICBAL,y
txa
sta ICBAH,y
ldx tmp4
lda #OPEN
sta ICCOM,x
jsr CIOV
; clean up the stack
finish: php
txa
pha
tya
pha
.ifdef UCASE_FILENAME
ldy tmp3 ; get size
jsr addysp ; free used space on the stack
.endif ; defined UCASE_FILENAME
jsr incsp4 ; clean up stack
pla
tay
pla
tax
plp
bpl ok
jsr fddecusage ; decrement usage counter of fd as open failed
jmp __do_oserror
ok: lda tmp2 ; get fd
ldx #0
stx __oserror
rts
.endproc
; find a free iocb
; no entry parameters
; return ZF = 0/1 for not found/found
; index in X if found
; all registers destroyed
.proc findfreeiocb
ldx #0
ldy #$FF
loop: tya
cmp ICHID,x
beq found
txa
clc
adc #$10
tax
cmp #$80
bcc loop
inx ; return ZF cleared
found: rts
.endproc
; clear iocb except for ICHID field
; expects X to be index to IOCB (0,$10,$20,etc.)
; all registers destroyed
.proc clriocb
inx ; don't clear ICHID
ldy #15
lda #0
loop: sta ICHID,x
dey
inx
bne loop
rts
.endproc