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         .import         lynxskip0, lynxblock
  27         .importzp       _FileEntry
  28         .importzp       _FileStartBlock
  29         .importzp       _FileCurrBlock
  30         .importzp       _FileBlockOffset
  31         .import         __STARTOFDIRECTORY__
  32         .export         _open
  33         .export         _openn
  34
  35         .include        "errno.inc"
  36         .include        "fcntl.inc"
  37
  38 .segment        "DATA"
  39
  40 _startofdirectory:
  41         .dword  __STARTOFDIRECTORY__
  42
  43 ; ---------------------------------------------------------------
  44 ; int __near__ open (__near__ const unsigned char*, int)
  45 ; ---------------------------------------------------------------
  46
  47 .segment        "CODE"
  48
  49 .proc   _open
  50
  51 .segment        "CODE"
  52
  53         dey
  54         dey
  55         dey
  56         dey
  57         beq     parmok
  58         jsr     addysp
  59
  60 parmok: jsr     popax
  61         sta     tmp3
  62         and     #(O_RDWR | O_CREAT)
  63         cmp     #O_RDONLY
  64         beq     flagsok
  65         cmp     #(O_WRONLY | O_CREAT)
  66         beq     flagsok
  67         jsr     popax
  68         lda     #EINVAL
  69         jmp     __directerrno
  70
  71 flagsok:
  72         jsr     popax
  73         jsr     _atoi
  74         jsr     _openn
  75         ldx     #$00
  76         lda     #$01
  77         stx     __oserror
  78         rts
  79
  80 .endproc
  81
  82 ; ---------------------------------------------------------------
  83 ; void __near__ __fastcall__ openn (int)
  84 ; ---------------------------------------------------------------
  85
  86 .segment        "CODE"
  87
  88 .proc   _openn: near
  89
  90 .segment        "CODE"
  91
  92         jsr     pushax
  93         jsr     decsp6
  94         lda     #$01
  95         jsr     pusha0
  96         lda     _startofdirectory+3
  97         sta     sreg+1
  98         lda     _startofdirectory+2
  99         sta     sreg
 100         ldx     _startofdirectory+1
 101         lda     _startofdirectory
 102         jsr     pusheax
 103         ldy     #$0D
 104         jsr     ldaxysp
 105         jsr     aslax3
 106         jsr     axlong
 107         jsr     tosaddeax
 108         jsr     pusheax
 109         ldx     #$00
 110         txa
 111         jsr     _lseek
 112         ldy     #$02
 113         jsr     steaxysp
 114         lda     #$01
 115         jsr     pusha0
 116         lda     #<_FileEntry
 117         ldx     #>_FileEntry
 118         jsr     pushax
 119         ldx     #$00
 120         lda     #$08
 121         jsr     _read
 122         lda     _FileStartBlock
 123         sta     _FileCurrBlock
 124         jsr     lynxblock
 125         lda     _FileBlockOffset+1
 126         eor     #$FF
 127         tay
 128         lda     _FileBlockOffset
 129         eor     #$FF
 130         tax
 131         jsr     lynxskip0
 132         jsr     stax0sp
 133         jmp     incsp8
 134
 135 .endproc
 136