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181 lines
2.9 KiB
ArmAsm
181 lines
2.9 KiB
ArmAsm
;
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; Christian Groessler, Jun-2004
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;
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; int __fastcall__ read(int fd,void *buf,int count)
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;
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.include "atari.inc"
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.import __rwsetup,__do_oserror,__inviocb,__oserror
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.export _read
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_read: jsr __rwsetup ; do common setup for read and write
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beq done ; if size 0, it's a no-op
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cpx #$FF ; invalid iocb?
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beq _inviocb
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.ifdef LINEBUF
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; E: should be always at IOCB #0
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; fixme: what happens when user closes and reopens stdin?
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cpx #0 ; E: handler (line oriented keyboard input)?
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beq do_line
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.endif
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lda #GETCHR ; iocb command code
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sta ICCOM,x
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jsr CIOV ; read it
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bpl done
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cpy #EOFERR ; eof is treated specially
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beq done
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jmp __do_oserror ; update errno
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done: lda ICBLL,x ; buf len lo
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pha ; save
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lda ICBLH,x ; get buf len hi
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tax ; to X
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okdone: lda #0
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sta __oserror ; clear system dependend error code
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pla ; get buf len lo
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rts
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_inviocb:
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jmp __inviocb
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.ifdef LINEBUF
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; line oriented input
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do_line:
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lda buflen ; line buffer active?
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bne use_buf ; yes, get data from there
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; save user buffer address & length
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; update IOCB to point to line buffer
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lda ICBLL,x
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pha
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lda #LINEBUF
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sta ICBLL,x
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;--------
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lda ICBLH,x
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pha
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lda #0
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sta ICBLH,x
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;--------
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lda ICBAL,x
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pha
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lda #<linebuf
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sta ICBAL,x
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;--------
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lda ICBAH,x
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pha
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lda #>linebuf
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sta ICBAH,x
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lda #GETREC
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sta ICCOM,x
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jsr CIOV ; read input data
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bpl newbuf
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cpy #EOFERR ; eof is treated specially
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beq newbuf
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pla ; fix stack
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pla
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pla
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pla
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jmp __do_oserror ; update errno
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newbuf:
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lda ICBLL,x ; get # of bytes read
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sta buflen
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lda #0
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sta index ; fresh buffer
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; restore user buffer address & length
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pla
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sta ICBAH,x
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;--------
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pla
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sta ICBAL,x
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;--------
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pla
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sta ICBLH,x
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;--------
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pla
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sta ICBLL,x
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; fall into use_buf
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lda buflen
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; return bytes from line buffer
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; use buflen and index to access buffer
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; update index
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; use dataptr as a temporary pointer
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use_buf:
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sec
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sbc index ; size of unread data in the buffer
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sta cbs
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lda ICBLL,x ; buf len lo
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cmp cbs ; larger than buffer size?
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beq bl1
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bcs btsmall ; yes, adjust length
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bl1: lda ICBLH,x ; get buf len hi
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bne btsmall ; buffer too small: buffer contents < read size
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; copy ICBLL,x bytes
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icbll_copy:
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lda ICBAL,x ; buffer address
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sta dataptr
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lda ICBAH,x ; buffer address
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sta dataptr+1
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lda ICBLL,x
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sta copylen
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pha ; remember for return value
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ldy #0
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ldx index
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copy: lda linebuf,x
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sta (dataptr),y
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iny
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inx
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dec copylen
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bne copy
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pla ; length
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pha ; save length to return at okdone
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clc
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adc index
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sta index
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cmp buflen ; buffer used up?
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bcc c1 ; not yet
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lda #0
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sta buflen ; indicate empty line buffer
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c1: ldx #0
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jmp okdone ; return to caller
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btsmall:
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lda cbs
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sta ICBLL,x
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bpl icbll_copy
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.zeropage
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index: .res 1 ; index into line buffer
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buflen: .res 1 ; length of used part of buffer
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cbs: .res 1 ; current buffer size: buflen - index
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dataptr:.res 2 ; temp pointer to user buffer
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copylen:.res 1 ; temp counter
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.bss
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linebuf:.res LINEBUF ; the line buffer
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.endif ; .ifdef LINEBUF
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