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