git.sur5r.net Git - cc65/blob - libsrc/lynx/open.s

   1 ;
   2 ; Karri Kaksonen, 2010
   3 ;
   4 ; This function reads the directory entry for file "name".
   5 ;
   6 ; The name is actually plain ASCII string starting from
   7 ; "0", "1", up to "4095" which is the largest file number we can handle.
   8 ;
   9 ; open() does not take part in what kind of cart we have. If it is RAM
  10 ; you may also be able to write into it. Therefore we allow both reads
  11 ; and writes in this routine.
  12 ;
  13 ; int open(const char *name, int flags, ...)
  14 ;
  15 ; As helper functions we also provide.
  16 ; void openn(int fileno)
  17 ;
  18         .importzp       sreg, tmp3
  19         .macpack        longbranch
  20         .import         _atoi
  21         .import         _read
  22         .import         _lseek
  23         .import         addysp,popax,pushax,decsp6,pusha0,pusheax,ldaxysp
  24         .import         aslax3,axlong,tosaddeax,steaxysp,stax0sp,incsp8
  25         .import         ldax0sp
  26         .importzp       _FileEntry
  27         .importzp       _FileStartBlock
  28         .importzp       _FileCurrBlock
  29         .importzp       _FileBlockOffset
  30         .import         __STARTOFDIRECTORY__
  31         .export         _open
  32         .export         _openn
  33
  34         .include        "errno.inc"
  35         .include        "fcntl.inc"
  36
  37 .segment        "DATA"
  38
  39 _startofdirectory:
  40         .dword  __STARTOFDIRECTORY__
  41
  42 ; ---------------------------------------------------------------
  43 ; int __near__ open (__near__ const unsigned char*, int)
  44 ; ---------------------------------------------------------------
  45
  46 .segment        "CODE"
  47
  48 .proc   _open
  49
  50 .segment        "CODE"
  51
  52         dey
  53         dey
  54         dey
  55         dey
  56         beq     parmok
  57         jsr     addysp
  58
  59 parmok: jsr     popax
  60         sta     tmp3
  61         and     #(O_RDWR | O_CREAT)
  62         cmp     #O_RDONLY
  63         beq     flagsok
  64         cmp     #(O_WRONLY | O_CREAT)
  65         beq     flagsok
  66         jsr     popax
  67         lda     #EINVAL
  68         jmp     __directerrno
  69
  70 flagsok:
  71         jsr     popax
  72         jsr     _atoi
  73         jsr     _openn
  74         ldx     #$00
  75         lda     #$01
  76         stx     __oserror
  77         rts
  78
  79 .endproc
  80
  81 ; ---------------------------------------------------------------
  82 ; void __near__ __fastcall__ openn (int)
  83 ; ---------------------------------------------------------------
  84
  85 .segment        "CODE"
  86
  87 .proc   _openn: near
  88
  89 .segment        "CODE"
  90
  91         jsr     pushax
  92         jsr     decsp6
  93         lda     #$01
  94         jsr     pusha0
  95         lda     _startofdirectory+3
  96         sta     sreg+1
  97         lda     _startofdirectory+2
  98         sta     sreg
  99         ldx     _startofdirectory+1
 100         lda     _startofdirectory
 101         jsr     pusheax
 102         ldy     #$0D
 103         jsr     ldaxysp
 104         jsr     aslax3
 105         jsr     axlong
 106         jsr     tosaddeax
 107         jsr     pusheax
 108         ldx     #$00
 109         txa
 110         jsr     _lseek
 111         ldy     #$02
 112         jsr     steaxysp
 113         lda     #$01
 114         jsr     pusha0
 115         lda     _FileEntry
 116         ldx     _FileEntry+1
 117         jsr     pushax
 118         ldx     #$00
 119         lda     #$08
 120         jsr     _read
 121         jsr     stax0sp
 122         jmp     incsp8
 123
 124 .endproc
 125