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81 lines
2.2 KiB
Plaintext
81 lines
2.2 KiB
Plaintext
;license:MIT
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;(c) 2018 by 4am
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;
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; Functions to build a ProDOS pathname from length-prefixed strings
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;
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; Public functions
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; - ResetPath
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; - AddToPath
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; - SetStartupPath
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;
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; Public variables
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; - gPathname
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;
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;------------------------------------------------------------------------------
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; ResetPath
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; reset gPathname to length 0
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;
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; in: none
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; out: all registers preserved
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;------------------------------------------------------------------------------
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ResetPath
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stz gPathname
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rts
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;------------------------------------------------------------------------------
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; AddToPath
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; append a length-prefixed string to gPathname
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;
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; in: A contains low byte of address of length-prefixed string to append
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; Y contains high byte of address of length-prefixed string to append
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; out: all registers and flags clobbered
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; $00/$01 clobbered
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; gPathname updated with concatenated length-prefixed string
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;------------------------------------------------------------------------------
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!zone {
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AddToPath
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sta $00
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sty $01
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ldx gPathname ; current pathname length
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lda ($00) ; length of this segment
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inc
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sta .a+1
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ldy #$01
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- lda ($00),y
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sta gPathname+1,x
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inx
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iny
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.a cpy #$FD ; SMC
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bcc -
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stx gPathname
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rts
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}
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;------------------------------------------------------------------------------
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; SetStartupPath
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; copy a length-prefixed string to $2006 (to pass it as the startup file when
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; launching a .system file)
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;
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; in: A contains low byte of address of length-prefixed string to append
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; Y contains high byte of address of length-prefixed string to append
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; out: all registers and flags clobbered
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; $00/$01 clobbered
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;------------------------------------------------------------------------------
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!zone {
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SetStartupPath
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sta $00
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sty $01
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lda ($00)
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tay
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- lda ($00),y
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and #$7F
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sta $2006,y
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dey
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bpl -
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rts
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}
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gPathname
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!fill 65 ; enough zeroes for any ProDOS pathname
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