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
52 ;----------------------------------------------------------------------------
56 ACIA_DATA = ACIA+0 ; Data register
57 ACIA_STATUS = ACIA+1 ; Status register
58 ACIA_CMD = ACIA+2 ; Command register
59 ACIA_CTRL = ACIA+3 ; Control register
61 ;----------------------------------------------------------------------------
67 RecvHead: .res 1 ; Head of receive buffer
68 RecvTail: .res 1 ; Tail of receive buffer
69 RecvFreeCnt: .res 1 ; Number of bytes in receive buffer
70 SendHead: .res 1 ; Head of send buffer
71 SendTail: .res 1 ; Tail of send buffer
72 SendFreeCnt: .res 1 ; Number of bytes in send buffer
74 Stopped: .res 1 ; Flow-stopped flag
77 ; Send and receive buffers: 256 bytes each
83 ; Tables used to translate RS232 params into register values
85 BaudTable: ; bit7 = 1 means setting is invalid
86 .byte $FF ; SER_BAUD_45_5
87 .byte $01 ; SER_BAUD_50
88 .byte $02 ; SER_BAUD_75
89 .byte $03 ; SER_BAUD_110
90 .byte $04 ; SER_BAUD_134_5
91 .byte $05 ; SER_BAUD_150
92 .byte $06 ; SER_BAUD_300
93 .byte $07 ; SER_BAUD_600
94 .byte $08 ; SER_BAUD_1200
95 .byte $09 ; SER_BAUD_1800
96 .byte $0A ; SER_BAUD_2400
97 .byte $0B ; SER_BAUD_3600
98 .byte $0C ; SER_BAUD_4800
99 .byte $0D ; SER_BAUD_7200
100 .byte $0E ; SER_BAUD_9600
101 .byte $0F ; SER_BAUD_19200
102 .byte $FF ; SER_BAUD_38400
103 .byte $FF ; SER_BAUD_57600
104 .byte $FF ; SER_BAUD_115200
105 .byte $FF ; SER_BAUD_230400
108 .byte $60 ; SER_BITS_5
109 .byte $40 ; SER_BITS_6
110 .byte $20 ; SER_BITS_7
111 .byte $00 ; SER_BITS_8
114 .byte $00 ; SER_STOP_1
115 .byte $80 ; SER_STOP_2
118 .byte $00 ; SER_PAR_NONE
119 .byte $20 ; SER_PAR_ODD
120 .byte $60 ; SER_PAR_EVEN
121 .byte $A0 ; SER_PAR_MARK
122 .byte $E0 ; SER_PAR_SPACE
126 ;----------------------------------------------------------------------------
127 ; INSTALL routine. Is called after the driver is loaded into memory. If
128 ; possible, check if the hardware is present.
129 ; Must return an SER_ERR_xx code in a/x.
131 ; Since we don't have to manage the IRQ vector on the Plus/4, this is actually
134 ; UNINSTALL routine. Is called before the driver is removed from memory.
135 ; Must return an SER_ERR_xx code in a/x.
139 ; CLOSE: Close the port, disable interrupts and flush the buffer. Called
140 ; without parameters. Must return an error code in a/x.
147 ; Deactivate DTR and disable 6551 interrupts
152 ; Done, return an error code
158 ;----------------------------------------------------------------------------
159 ; PARAMS routine. A pointer to a ser_params structure is passed in ptr1.
160 ; Must return an SER_ERR_xx code in a/x.
164 ; Check if the handshake setting is valid
166 ldy #SER_PARAMS::HANDSHAKE ; Handshake
168 cmp #SER_HS_HW ; This is all we support
175 ; Set the value for the control register, which contains stop bits, word
176 ; length and the baud rate.
178 ldy #SER_PARAMS::BAUDRATE
179 lda (ptr1),y ; Baudrate index
181 lda BaudTable,y ; Get 6551 value
182 bmi InvBaud ; Branch if rate not supported
185 ldy #SER_PARAMS::DATABITS ; Databits
192 ldy #SER_PARAMS::STOPBITS ; Stopbits
197 ora #%00010000 ; Receiver clock source = baudrate
200 ; Set the value for the command register. We remember the base value in
201 ; RtsOff, since we will have to manipulate ACIA_CMD often.
203 ldy #SER_PARAMS::PARITY ; Parity
207 ora #%00000001 ; DTR active
209 ora #%00001000 ; Enable receive interrupts
221 lda #<SER_ERR_INIT_FAILED
222 ldx #>SER_ERR_INIT_FAILED
225 ; Baud rate not available
228 lda #<SER_ERR_BAUD_UNAVAIL
229 ldx #>SER_ERR_BAUD_UNAVAIL
232 ;----------------------------------------------------------------------------
233 ; GET: Will fetch a character from the receive buffer and store it into the
234 ; variable pointer to by ptr1. If no data is available, SER_ERR_NO_DATA is
238 GET: ldx SendFreeCnt ; Send data if necessary
244 ; Check for buffer empty
246 @L1: lda RecvFreeCnt ; (25)
249 lda #<SER_ERR_NO_DATA
250 ldx #>SER_ERR_NO_DATA
253 ; Check for flow stopped & enough free: release flow control
255 @L2: ldx Stopped ; (34)
265 ; Get byte from buffer
267 @L3: ldx RecvHead ; (41)
273 txa ; Return code = 0
276 ;----------------------------------------------------------------------------
277 ; PUT: Output character in A.
278 ; Must return an error code in a/x.
293 ; Put byte into send buffer & send
297 lda #<SER_ERR_OVERFLOW ; X is already zero
310 ;----------------------------------------------------------------------------
311 ; STATUS: Return the status in the variable pointed to by ptr1.
312 ; Must return an error code in a/x.
315 STATUS: lda ACIA_STATUS
321 ;----------------------------------------------------------------------------
322 ; IOCTL: Driver defined entry point. The wrapper will pass a pointer to ioctl
323 ; specific data in ptr1, and the ioctl code in A.
324 ; Must return an error code in a/x.
327 IOCTL: lda #<SER_ERR_INV_IOCTL ; We don't support ioclts for now
328 ldx #>SER_ERR_INV_IOCTL
329 rts ; Run into IRQ instead
331 ;----------------------------------------------------------------------------
332 ; IRQ: Called from the builtin runtime IRQ handler as a subroutine. All
333 ; registers are already save, no parameters are passed, but the carry flag
334 ; is clear on entry. The routine must return with carry set if the interrupt
335 ; was handled, otherwise with carry clear.
338 IRQ: lda ACIA_STATUS ; Check ACIA status for receive interrupt
340 beq @L9 ; Jump if no ACIA interrupt (carry still clear)
341 lda ACIA_DATA ; Get byte from ACIA
342 ldx RecvFreeCnt ; Check if we have free space left
343 beq @L1 ; Jump if no space in receive buffer
344 ldy RecvTail ; Load buffer pointer
345 sta RecvBuf,y ; Store received byte in buffer
346 inc RecvTail ; Increment buffer pointer
347 dec RecvFreeCnt ; Decrement free space counter
348 cpx #33 ; Check for buffer space low
349 bcc @L1 ; Assert flow control if buffer space low
350 rts ; Return with carry set (interrupt handled)
352 ; Assert flow control if buffer space too low
357 sec ; Interrupt handled
360 ;----------------------------------------------------------------------------
361 ; Try to send a byte. Internal routine. A = TryHard
365 sta tmp1 ; Remember tryHard flag
370 ; Check for flow stopped
375 ; Check that swiftlink is ready to send
380 bit tmp1 ;keep trying if must try hard
384 ; Send byte and try again
396 ;----------------------------------------------------------------------------