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|
;
; Karri Kaksonen, 2010
;
; This function reads the directory entry for file "name".
;
; The name is actually plain ASCII string starting from
; "0", "1", up to "4095" which is the largest file number we can handle.
;
; open() does not take part in what kind of cart we have. If it is RAM
; you may also be able to write into it. Therefore we allow both reads
; and writes in this routine.
;
; int open(const char *name, int flags, ...)
;
; As helper functions we also provide.
; void openn(int fileno)
;
.importzp sreg, tmp3
.macpack longbranch
.import _atoi
.import _read
.import _lseek
.import addysp,popax,pushax,decsp6,pusha0,pusheax,ldaxysp
.import aslax3,axlong,tosaddeax,steaxysp,stax0sp,incsp8
.import ldax0sp
.import lynxskip0, lynxblock
.importzp _FileEntry
.importzp _FileStartBlock
.importzp _FileCurrBlock
.importzp _FileBlockOffset
.import __STARTOFDIRECTORY__
.export _open
.export _openn
.include "errno.inc"
.include "fcntl.inc"
.segment "DATA"
_startofdirectory:
.dword __STARTOFDIRECTORY__
; ---------------------------------------------------------------
; int __near__ open (__near__ const unsigned char*, int)
; ---------------------------------------------------------------
.segment "CODE"
.proc _open
.segment "CODE"
dey
dey
dey
dey
beq parmok
jsr addysp
parmok: jsr popax
sta tmp3
and #(O_RDWR | O_CREAT)
cmp #O_RDONLY
beq flagsok
cmp #(O_WRONLY | O_CREAT)
beq flagsok
jsr popax
lda #EINVAL
jmp __directerrno
flagsok:
jsr popax
jsr _atoi
jsr _openn
ldx #$00
lda #$01
stx __oserror
rts
.endproc
; ---------------------------------------------------------------
; void __near__ __fastcall__ openn (int)
; ---------------------------------------------------------------
.segment "CODE"
.proc _openn: near
.segment "CODE"
jsr pushax
jsr decsp6
lda #$01
jsr pusha0
lda _startofdirectory+3
sta sreg+1
lda _startofdirectory+2
sta sreg
ldx _startofdirectory+1
lda _startofdirectory
jsr pusheax
ldy #$0D
jsr ldaxysp
jsr aslax3
jsr axlong
jsr tosaddeax
jsr pusheax
ldx #$00
txa
jsr _lseek
ldy #$02
jsr steaxysp
lda #$01
jsr pusha0
lda #<_FileEntry
ldx #>_FileEntry
jsr pushax
ldx #$00
lda #$08
jsr _read
lda _FileStartBlock
sta _FileCurrBlock
jsr lynxblock
lda _FileBlockOffset+1
eor #$FF
tay
lda _FileBlockOffset
eor #$FF
tax
jsr lynxskip0
jsr stax0sp
jmp incsp8
.endproc
|
