mirror of https://github.com/option8/gp2io.git
71 lines
3.0 KiB
ArmAsm
71 lines
3.0 KiB
ArmAsm
ORG $800
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BUFFERLENGTH EQU $08
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INPUTLENGTH EQU $07
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INPUTPTR EQU $06
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SENDBYTE EQU $0300
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READBYTE EQU $034A
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WAIT EQU $FCA8
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PRINTCR EQU $FD8E
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PRINTBYTE EQU $FDED
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ANN2HI EQU $C05D
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ANN2LO EQU $C05C
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KEYBUFFER EQU $0200
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BUFFERIO JSR QUERYBUFFER ; start by querying the buffer length - is there anything waiting? returns with buffer length in $08
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LDA #$80 ; load control byte $80 "send buffer bytes"
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JSR SENDBYTE ; send control byte
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LDA BUFFERLENGTH ; load buffer length (or however much buffer you want sent)
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JSR SENDBYTE ; send message length byte
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BETWEENBYTES LDA #$28 ; wait a moment (betweenbytes)
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JSR WAIT ; wait
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JSR READBYTE ; CTS - send byte
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ORA #$80 ; clear byte 7 (for ASCII)
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JSR PRINTBYTE ; display byte on screen
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DEC BUFFERLENGTH ; count down bytes (countdownbuffer)
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LDA BUFFERLENGTH ; load Accumulator with new buffer length
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BNE BETWEENBYTES ; if there's more to come, loop (betweenbytes)
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JSR PRINTCR ; last byte. print CF/LF
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RTS ; return
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GETLINE JSR $FD6A ; get line of input, input length in X reg
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TXA ; get input length into Accumulator
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STA INPUTLENGTH ; put input length into $07
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CLEARPTR LDA #$00 ; load zero into Accumulator
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STA INPUTPTR ; put zero into $06, keyboard buffer pointer
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LDA #$04 ; load Accumulator with control byte "write to buffer"
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JSR SENDBYTE ; send control byte
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LDA INPUTLENGTH ; load input length from $07
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JSR SENDBYTE ; send message length
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LOADBUFFER LDX INPUTPTR ; load X with keyboard buffer pointer (LOADBUFFER)
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LDA KEYBUFFER,X ; load Accumulator with bytes from keyboard buffer (start at $200)
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AND #$7F ; clear high bit (for ASCII on other end)
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JSR SENDBYTE ; send byte
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INC INPUTPTR ; increment keyboard buffer pointer
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LDA INPUTPTR ; load buffer pointer into Accumulator
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CMP INPUTLENGTH ; compare with message length
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BNE LOADBUFFER ; if not at end of message, loop to (LOADBUFFER)
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RTS ; return
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QUERYBUFFER LDA #$40 ; control byte for query buffer length
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JSR SENDBYTE ; send control byte
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JSR TWIDDLE ; wait routine - gives GP2IO time to receive bytes from serial
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CTS STA ANN2LO ; set ANN2 to LOW (just in case it's floating high)
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JSR READBYTE ; CTS - ready for response byte with buffer length
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BEQ QUERYBUFFER ; if there's nothing in the buffer, loop until there is
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STA BUFFERLENGTH ; put the byte in $08
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RTS ; returns buffer length in $08 (BUFFERLENGTH)
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TWIDDLE LDA #$21 ; ! (inverse)
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JSR PRINTCHAR ;
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LDA #$2F ; /
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JSR PRINTCHAR ;
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LDA #$2D ; -
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JSR PRINTCHAR ;
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LDA #$1C ; \
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PRINTCHAR JSR PRINTBYTE ; prints character to screen, high byte not set, inverse text
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LDA #$AA ; speed of animation
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JSR WAIT ; waits for a while
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LDA #$88 ; (backspace)
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JSR PRINTBYTE ; backspaces over current char to overwrite
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RTS ; RETURN
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