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https://github.com/jonthomasson/retro1.git
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94 lines
3.1 KiB
Plaintext
94 lines
3.1 KiB
Plaintext
.setcpu "65C02"
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.include "zeropage.inc65"
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.include "io.inc65"
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.include "macros.inc65"
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ACIA_BUFFER_LENGTH = 10
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.export acia_init
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.export acia_getc
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.export acia_gets
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.export acia_gets_buffer
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.export acia_putc
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.export acia_puts
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.export acia_put_newline
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.bss
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acia_gets_buffer: .res ACIA_BUFFER_LENGTH + 1, 0
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.code
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; Initialize the ACIA
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acia_init: pha
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lda #(ACIA_PARITY_DISABLE | ACIA_ECHO_DISABLE | ACIA_TX_INT_DISABLE_RTS_LOW | ACIA_RX_INT_DISABLE | ACIA_DTR_LOW)
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sta ACIA_COMMAND
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lda #(ACIA_STOP_BITS_1 | ACIA_DATA_BITS_8 | ACIA_CLOCK_INT | ACIA_BAUD_19200)
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sta ACIA_CONTROL
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pla
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rts
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; Send the character in A
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acia_putc: pha
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wait_txd_empty: lda ACIA_STATUS
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and #ACIA_STATUS_TX_EMPTY
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beq wait_txd_empty
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pla
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sta ACIA_DATA
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rts
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; Send the zero terminated string pointed to by R0
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acia_puts: phay
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ldy #$ff
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next_char: iny
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lda (R0),y
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jsr acia_putc
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bne next_char
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play
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rts
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; Wait until a character was reveiced and return it in A
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acia_getc:
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wait_rxd_full: lda ACIA_STATUS
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and #ACIA_STATUS_RX_FULL
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beq wait_rxd_full
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lda ACIA_DATA
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rts
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; Wait until a \n terminated string was received and store it at (R0)
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; The accu contains the size of the buffer
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; The \n is removed and the string is zero terminated
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; After receiving buffer size - 1 characters, any following characters are discarded
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acia_gets: sta TMP0
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phay
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ldy #0
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gets_next_char: jsr acia_getc
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jsr acia_putc ;echo back to screen
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cmp #$0a ;is it end of line?
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beq gets_eos
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cmp #$08 ;is it a backspace?
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beq gets_backspace
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gets_buff_test: cpy TMP0 ;is buffer full?
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beq gets_next_char
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sta (R0),y
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iny
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jmp gets_next_char
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gets_backspace: dey ;decrement y
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bmi gets_reinit ;beyond start of line, reinitialize
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lda #$20 ;replace backspace with space
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sta (R0),y ;store space in buffer
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jsr acia_putc ;blank out existing char on screen
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lda #$08 ;backspace again to get correct position
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jsr acia_putc
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jmp gets_next_char
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gets_reinit: lda TMP0 ;restore a
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jmp acia_gets ;start over
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gets_eos: lda #0
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sta (R0),y
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play
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rts
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; Send a newline character
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acia_put_newline: lda #$0a ;lf
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jmp acia_putc
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