2 ; Serial driver for the builtin 6551 ACIA of the Plus/4.
4 ; Ullrich von Bassewitz, 2003-12-13
6 ; The driver is based on the cc65 rs232 module, which in turn is based on
7 ; Craig Bruce device driver for the Switftlink/Turbo-232.
9 ; SwiftLink/Turbo-232 v0.90 device driver, by Craig Bruce, 14-Apr-1998.
11 ; This software is Public Domain. It is in Buddy assembler format.
13 ; This device driver uses the SwiftLink RS-232 Serial Cartridge, available from
14 ; Creative Micro Designs, Inc, and also supports the extensions of the Turbo232
15 ; Serial Cartridge. Both devices are based on the 6551 ACIA chip. It also
16 ; supports the "hacked" SwiftLink with a 1.8432 MHz crystal.
18 ; The code assumes that the kernal + I/O are in context. On the C128, call
19 ; it from Bank 15. On the C64, don't flip out the Kernal unless a suitable
20 ; NMI catcher is put into the RAM under then Kernal. For the SuperCPU, the
21 ; interrupt handling assumes that the 65816 is in 6502-emulation mode.
24 .include "zeropage.inc"
25 .include "ser-kernel.inc"
26 .include "ser-error.inc"
30 ; ------------------------------------------------------------------------
31 ; Header. Includes jump table
37 .byte $73, $65, $72 ; "ser"
38 .byte SER_API_VERSION ; Serial API version number
56 ;----------------------------------------------------------------------------
60 ACIA_DATA = ACIA+0 ; Data register
61 ACIA_STATUS = ACIA+1 ; Status register
62 ACIA_CMD = ACIA+2 ; Command register
63 ACIA_CTRL = ACIA+3 ; Control register
65 ;----------------------------------------------------------------------------
71 RecvHead: .res 1 ; Head of receive buffer
72 RecvTail: .res 1 ; Tail of receive buffer
73 RecvFreeCnt: .res 1 ; Number of bytes in receive buffer
74 SendHead: .res 1 ; Head of send buffer
75 SendTail: .res 1 ; Tail of send buffer
76 SendFreeCnt: .res 1 ; Number of bytes in send buffer
78 Stopped: .res 1 ; Flow-stopped flag
81 ; Send and receive buffers: 256 bytes each
87 ; Tables used to translate RS232 params into register values
89 BaudTable: ; bit7 = 1 means setting is invalid
90 .byte $FF ; SER_BAUD_45_5
91 .byte $01 ; SER_BAUD_50
92 .byte $02 ; SER_BAUD_75
93 .byte $03 ; SER_BAUD_110
94 .byte $04 ; SER_BAUD_134_5
95 .byte $05 ; SER_BAUD_150
96 .byte $06 ; SER_BAUD_300
97 .byte $07 ; SER_BAUD_600
98 .byte $08 ; SER_BAUD_1200
99 .byte $09 ; SER_BAUD_1800
100 .byte $0A ; SER_BAUD_2400
101 .byte $0B ; SER_BAUD_3600
102 .byte $0C ; SER_BAUD_4800
103 .byte $0D ; SER_BAUD_7200
104 .byte $0E ; SER_BAUD_9600
105 .byte $0F ; SER_BAUD_19200
106 .byte $FF ; SER_BAUD_38400
107 .byte $FF ; SER_BAUD_57600
108 .byte $FF ; SER_BAUD_115200
109 .byte $FF ; SER_BAUD_230400
112 .byte $60 ; SER_BITS_5
113 .byte $40 ; SER_BITS_6
114 .byte $20 ; SER_BITS_7
115 .byte $00 ; SER_BITS_8
118 .byte $00 ; SER_STOP_1
119 .byte $80 ; SER_STOP_2
122 .byte $00 ; SER_PAR_NONE
123 .byte $20 ; SER_PAR_ODD
124 .byte $60 ; SER_PAR_EVEN
125 .byte $A0 ; SER_PAR_MARK
126 .byte $E0 ; SER_PAR_SPACE
130 ;----------------------------------------------------------------------------
131 ; INSTALL routine. Is called after the driver is loaded into memory. If
132 ; possible, check if the hardware is present.
133 ; Must return an SER_ERR_xx code in a/x.
135 ; Since we don't have to manage the IRQ vector on the Plus/4, this is actually
138 ; UNINSTALL routine. Is called before the driver is removed from memory.
139 ; Must return an SER_ERR_xx code in a/x.
143 ; CLOSE: Close the port, disable interrupts and flush the buffer. Called
144 ; without parameters. Must return an error code in a/x.
151 ; Deactivate DTR and disable 6551 interrupts
156 ; Done, return an error code
162 ;----------------------------------------------------------------------------
163 ; PARAMS routine. A pointer to a ser_params structure is passed in ptr1.
164 ; Must return an SER_ERR_xx code in a/x.
168 ; Check if the handshake setting is valid
170 ldy #SER_PARAMS::HANDSHAKE ; Handshake
172 cmp #SER_HS_HW ; This is all we support
187 ; Set the value for the control register, which contains stop bits, word
188 ; length and the baud rate.
190 ldy #SER_PARAMS::BAUDRATE
191 lda (ptr1),y ; Baudrate index
193 lda BaudTable,y ; Get 6551 value
194 bmi InvBaud ; Branch if rate not supported
197 ldy #SER_PARAMS::DATABITS ; Databits
204 ldy #SER_PARAMS::STOPBITS ; Stopbits
209 ora #%00010000 ; Receiver clock source = baudrate
212 ; Set the value for the command register. We remember the base value in
213 ; RtsOff, since we will have to manipulate ACIA_CMD often.
215 ldy #SER_PARAMS::PARITY ; Parity
219 ora #%00000001 ; DTR active
221 ora #%00001000 ; Enable receive interrupts
233 lda #<SER_ERR_INIT_FAILED
234 ldx #>SER_ERR_INIT_FAILED
237 ; Baud rate not available
240 lda #<SER_ERR_BAUD_UNAVAIL
241 ldx #>SER_ERR_BAUD_UNAVAIL
244 ;----------------------------------------------------------------------------
245 ; GET: Will fetch a character from the receive buffer and store it into the
246 ; variable pointer to by ptr1. If no data is available, SER_ERR_NO_DATA is
250 GET: ldx SendFreeCnt ; Send data if necessary
256 ; Check for buffer empty
258 @L1: lda RecvFreeCnt ; (25)
261 lda #<SER_ERR_NO_DATA
262 ldx #>SER_ERR_NO_DATA
265 ; Check for flow stopped & enough free: release flow control
267 @L2: ldx Stopped ; (34)
277 ; Get byte from buffer
279 @L3: ldx RecvHead ; (41)
285 txa ; Return code = 0
288 ;----------------------------------------------------------------------------
289 ; PUT: Output character in A.
290 ; Must return an error code in a/x.
305 ; Put byte into send buffer & send
309 lda #<SER_ERR_OVERFLOW ; X is already zero
322 ;----------------------------------------------------------------------------
323 ; STATUS: Return the status in the variable pointed to by ptr1.
324 ; Must return an error code in a/x.
327 STATUS: lda ACIA_STATUS
333 ;----------------------------------------------------------------------------
334 ; IOCTL: Driver defined entry point. The wrapper will pass a pointer to ioctl
335 ; specific data in ptr1, and the ioctl code in A.
336 ; Must return an error code in a/x.
339 IOCTL: lda #<SER_ERR_INV_IOCTL ; We don't support ioclts for now
340 ldx #>SER_ERR_INV_IOCTL
341 rts ; Run into IRQ instead
343 ;----------------------------------------------------------------------------
344 ; IRQ: Called from the builtin runtime IRQ handler as a subroutine. All
345 ; registers are already save, no parameters are passed, but the carry flag
346 ; is clear on entry. The routine must return with carry set if the interrupt
347 ; was handled, otherwise with carry clear.
350 IRQ: lda ACIA_STATUS ; Check ACIA status for receive interrupt
352 beq @L9 ; Jump if no ACIA interrupt (carry still clear)
353 lda ACIA_DATA ; Get byte from ACIA
354 ldx RecvFreeCnt ; Check if we have free space left
355 beq @L1 ; Jump if no space in receive buffer
356 ldy RecvTail ; Load buffer pointer
357 sta RecvBuf,y ; Store received byte in buffer
358 inc RecvTail ; Increment buffer pointer
359 dec RecvFreeCnt ; Decrement free space counter
360 cpx #33 ; Check for buffer space low
361 bcc @L1 ; Assert flow control if buffer space low
362 rts ; Return with carry set (interrupt handled)
364 ; Assert flow control if buffer space too low
369 sec ; Interrupt handled
372 ;----------------------------------------------------------------------------
373 ; Try to send a byte. Internal routine. A = TryHard
377 sta tmp1 ; Remember tryHard flag
382 ; Check for flow stopped
387 ; Check that swiftlink is ready to send
392 bit tmp1 ;keep trying if must try hard
396 ; Send byte and try again