Apple2-IO-RPi/Apple2/Shell.asm

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2021-11-05 19:15:54 +00:00
;ProDOS Zero Page
Command = $42 ;ProDOS Command
Unit = $43 ;ProDOS unit (SDDD0000)
BufferLo = $44
BufferHi = $45
BlockLo = $46
BlockHi = $47
; ProDOS Error Codes
IOError = $27
NoDevice = $28
WriteProtect = $2B
; hard code slot to 7 for now, will make it auto-detect later
SLOT = 7
InputByte = $c08e+SLOT*$10
OutputByte = $c08d+SLOT*$10
InputFlags = $c08b+SLOT*$10
OutputFlags = $c087+SLOT*$10
ReadBlockCommand = $01
WriteBlockCommand = $02
GetTimeCommand = $03
ChangeDriveCommand = $04
ExecCommand = $05
LoadFileCommand = $06
SaveFileCommand = $07
MenuCommand = $08
InputString = $fd6a
StringBuffer = $0200
PrintChar = $fded
Keyboard = $c000
ClearKeyboard = $c010
Wait = $fca8
PromptChar = $33
ESC = $9b
.org $2000
Start:
lda PromptChar
sta OldPromptChar
lda #'$'|$80
sta PromptChar
lda #ExecCommand
jsr SendByte
ldx #$00
sendHelpCommand:
lda HelpCommand,x
cmp #$00
beq sendHelpCommandEnd
jsr SendByte
inx
bpl sendHelpCommand
sendHelpCommandEnd:
lda #$00
jsr SendByte
bit ClearKeyboard
jsr DumpOutput
Prompt:
lda #ExecCommand
jsr SendByte
ldx #$00
sendPromptCommand:
lda PromptCommand,x
cmp #$00
beq sendPromptCommandEnd
jsr SendByte
inx
bpl sendPromptCommand
sendPromptCommandEnd:
lda #$00
jsr SendByte
bit ClearKeyboard
jsr DumpOutput
; get input
jsr InputString
; check for "exit"
lda StringBuffer
cmp #'e'|$80
bne Execute
lda StringBuffer+1
cmp #'x'|$80
bne Execute
lda StringBuffer+2
cmp #'i'|$80
bne Execute
lda StringBuffer+3
cmp #'t'|$80
bne Execute
lda OldPromptChar
sta PromptChar
rts
Execute:
bit ClearKeyboard
lda #ExecCommand
jsr SendByte
ldy #$00
sendInput:
lda $0200,y
cmp #$8d
beq sendNullTerminator
and #$7f
jsr SendByte
iny
bne sendInput
sendNullTerminator:
lda #$00
jsr SendByte
jsr DumpOutput
jmp Prompt
DumpOutput:
jsr GetByte
bcs skipOutput
cmp #$00
beq endOutput
cmp #ESC
beq escapeSequence
jsr PrintChar
skipOutput:
bit Keyboard ;check for keypress
bpl DumpOutput ;keep dumping output if no keypress
lda Keyboard ;send keypress to RPi
;jsr PrintChar
and #$7f
jsr SendByte
bit ClearKeyboard
clc
bcc DumpOutput
endOutput:
rts
escapeSequence:
jsr ParseEscape
clc
bcc DumpOutput
ParseEscape:
jsr GetByte ; expect first byte after ESC to be '['
cmp #'['|$80
beq endParse
checkLetter:
jsr GetByte ; loop until there is a letter
cmp #$C1
bcc checkLetter
endParse:
rts
SendByte:
pha
waitWrite:
lda InputFlags
rol
rol
bcs waitWrite
pla
sta OutputByte
lda #$1e ; set bit 0 low to indicate write started
sta OutputFlags
finishWrite:
lda InputFlags
rol
rol
bcc finishWrite
lda #$1f
sta OutputFlags
rts
GetByte:
lda #$1d ;set read flag low
sta OutputFlags
waitRead:
lda InputFlags
rol
bcc readByte
bit Keyboard ;keypress will abort waiting to read
bpl waitRead
lda #$1f ;set all flags high and exit
sta OutputFlags
sec ;failure
rts
readByte:
lda InputByte
pha
lda #$1f ;set all flags high
sta OutputFlags
finishRead:
lda InputFlags
rol
bcc finishRead
pla
clc ;success
end:
rts
HelpCommand:
.byte "a2help",$00
PromptCommand:
.byte "a2prompt",$00
OldPromptChar:
.byte "]"