2 ; Serial driver for the builtin 6551 ACIA of the Commodore 610.
4 ; Ullrich von Bassewitz, 2003-12-18
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 "../extzp.inc"
26 .include "ser-kernel.inc"
27 .include "ser-error.inc"
31 ; ------------------------------------------------------------------------
32 ; Header. Includes jump table
38 .byte $73, $65, $72 ; "ser"
39 .byte SER_API_VERSION ; Serial API version number
57 ;----------------------------------------------------------------------------
63 RecvHead: .res 1 ; Head of receive buffer
64 RecvTail: .res 1 ; Tail of receive buffer
65 RecvFreeCnt: .res 1 ; Number of bytes in receive buffer
66 SendHead: .res 1 ; Head of send buffer
67 SendTail: .res 1 ; Tail of send buffer
68 SendFreeCnt: .res 1 ; Number of bytes in send buffer
70 Stopped: .res 1 ; Flow-stopped flag
73 ; Send and receive buffers: 256 bytes each
79 ; Tables used to translate RS232 params into register values
81 BaudTable: ; bit7 = 1 means setting is invalid
82 .byte $FF ; SER_BAUD_45_5
83 .byte $01 ; SER_BAUD_50
84 .byte $02 ; SER_BAUD_75
85 .byte $03 ; SER_BAUD_110
86 .byte $04 ; SER_BAUD_134_5
87 .byte $05 ; SER_BAUD_150
88 .byte $06 ; SER_BAUD_300
89 .byte $07 ; SER_BAUD_600
90 .byte $08 ; SER_BAUD_1200
91 .byte $09 ; SER_BAUD_1800
92 .byte $0A ; SER_BAUD_2400
93 .byte $0B ; SER_BAUD_3600
94 .byte $0C ; SER_BAUD_4800
95 .byte $0D ; SER_BAUD_7200
96 .byte $0E ; SER_BAUD_9600
97 .byte $0F ; SER_BAUD_19200
98 .byte $FF ; SER_BAUD_38400
99 .byte $FF ; SER_BAUD_57600
100 .byte $FF ; SER_BAUD_115200
101 .byte $FF ; SER_BAUD_230400
104 .byte $60 ; SER_BITS_5
105 .byte $40 ; SER_BITS_6
106 .byte $20 ; SER_BITS_7
107 .byte $00 ; SER_BITS_8
110 .byte $00 ; SER_STOP_1
111 .byte $80 ; SER_STOP_2
114 .byte $00 ; SER_PAR_NONE
115 .byte $20 ; SER_PAR_ODD
116 .byte $60 ; SER_PAR_EVEN
117 .byte $A0 ; SER_PAR_MARK
118 .byte $E0 ; SER_PAR_SPACE
122 ;----------------------------------------------------------------------------
123 ; INSTALL routine. Is called after the driver is loaded into memory. If
124 ; possible, check if the hardware is present.
125 ; Must return an SER_ERR_xx code in a/x.
127 ; Since we don't have to manage the IRQ vector on the Plus/4, this is actually
130 ; UNINSTALL routine. Is called before the driver is removed from memory.
131 ; Must return an SER_ERR_xx code in a/x.
135 ; CLOSE: Close the port, disable interrupts and flush the buffer. Called
136 ; without parameters. Must return an error code in a/x.
143 ; Deactivate DTR and disable 6551 interrupts
148 ; Done, return an error code
154 ;----------------------------------------------------------------------------
155 ; PARAMS routine. A pointer to a ser_params structure is passed in ptr1.
156 ; Must return an SER_ERR_xx code in a/x.
160 ; Check if the handshake setting is valid
162 ldy #SER_PARAMS::HANDSHAKE ; Handshake
164 cmp #SER_HS_HW ; This is all we support
179 ; Set the value for the control register, which contains stop bits, word
180 ; length and the baud rate.
182 ldy #SER_PARAMS::BAUDRATE
183 lda (ptr1),y ; Baudrate index
185 lda BaudTable,y ; Get 6551 value
186 bmi InvBaud ; Branch if rate not supported
189 ldy #SER_PARAMS::DATABITS ; Databits
196 ldy #SER_PARAMS::STOPBITS ; Stopbits
201 ora #%00010000 ; Receiver clock source = baudrate
205 ; Set the value for the command register. We remember the base value in
206 ; RtsOff, since we will have to manipulate ACIA_CMD often.
208 ldy #SER_PARAMS::PARITY ; Parity
212 ora #%00000001 ; DTR active
214 ora #%00001000 ; Enable receive interrupts
226 lda #<SER_ERR_INIT_FAILED
227 ldx #>SER_ERR_INIT_FAILED
230 ; Baud rate not available
233 lda #<SER_ERR_BAUD_UNAVAIL
234 ldx #>SER_ERR_BAUD_UNAVAIL
237 ;----------------------------------------------------------------------------
238 ; GET: Will fetch a character from the receive buffer and store it into the
239 ; variable pointer to by ptr1. If no data is available, SER_ERR_NO_DATA is
243 GET: ldx SendFreeCnt ; Send data if necessary
249 ; Check for buffer empty
254 lda #<SER_ERR_NO_DATA
255 ldx #>SER_ERR_NO_DATA
258 ; Check for flow stopped & enough free: release flow control
270 ; Get byte from buffer
278 txa ; Return code = 0
281 ;----------------------------------------------------------------------------
282 ; PUT: Output character in A.
283 ; Must return an error code in a/x.
298 ; Put byte into send buffer & send
302 lda #<SER_ERR_OVERFLOW ; X is already zero
315 ;----------------------------------------------------------------------------
316 ; STATUS: Return the status in the variable pointed to by ptr1.
317 ; Must return an error code in a/x.
331 ;----------------------------------------------------------------------------
332 ; IOCTL: Driver defined entry point. The wrapper will pass a pointer to ioctl
333 ; specific data in ptr1, and the ioctl code in A.
334 ; Must return an error code in a/x.
337 IOCTL: lda #<SER_ERR_INV_IOCTL ; We don't support ioclts for now
338 ldx #>SER_ERR_INV_IOCTL
341 ;----------------------------------------------------------------------------
342 ; IRQ: Called from the builtin runtime IRQ handler as a subroutine. All
343 ; registers are already save, no parameters are passed, but the carry flag
344 ; is clear on entry. The routine must return with carry set if the interrupt
345 ; was handled, otherwise with carry clear.
349 sta IndReg ; Switch to the system bank
351 lda (acia),y ; Check ACIA status for receive interrupt
353 beq @L9 ; Jump if no ACIA interrupt (carry still clear)
355 lda (acia),y ; Get byte from ACIA
356 ldx RecvFreeCnt ; Check if we have free space left
357 beq @L1 ; Jump if no space in receive buffer
358 ldy RecvTail ; Load buffer pointer
359 sta RecvBuf,y ; Store received byte in buffer
360 inc RecvTail ; Increment buffer pointer
361 dec RecvFreeCnt ; Decrement free space counter
362 cpx #33 ; Check for buffer space low
363 bcs @L9 ; Assert flow control if buffer space low
365 ; Assert flow control if buffer space too low
371 sec ; Interrupt handled
373 ; Done, switch back to the execution segment
379 ;----------------------------------------------------------------------------
380 ; Try to send a byte. Internal routine. A = TryHard
384 sta tmp1 ; Remember tryHard flag
386 sta IndReg ; Switch to the system bank
391 ; Check for flow stopped
396 ; Check that swiftlink is ready to send
398 @L2: ldy #ACIA::STATUS
402 bit tmp1 ; Keep trying if must try hard
405 ; Switch back the bank and return
411 ; Send byte and try again
424 ;----------------------------------------------------------------------------
425 ; Write to the ACIA changing the indirect segment. Offset is in Y, value in A.