2 ; Serial driver for the builtin 6551 ACIA of the Commodore 510.
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"
33 ; ------------------------------------------------------------------------
34 ; Header. Includes jump table
36 module_header _cbm510_std_ser
40 .byte $73, $65, $72 ; "ser"
41 .byte SER_API_VERSION ; Serial API version number
59 ;----------------------------------------------------------------------------
65 RecvHead: .res 1 ; Head of receive buffer
66 RecvTail: .res 1 ; Tail of receive buffer
67 RecvFreeCnt: .res 1 ; Number of bytes in receive buffer
68 SendHead: .res 1 ; Head of send buffer
69 SendTail: .res 1 ; Tail of send buffer
70 SendFreeCnt: .res 1 ; Number of bytes in send buffer
72 Stopped: .res 1 ; Flow-stopped flag
75 ; Send and receive buffers: 256 bytes each
81 ; Tables used to translate RS232 params into register values
83 BaudTable: ; bit7 = 1 means setting is invalid
84 .byte $FF ; SER_BAUD_45_5
85 .byte $01 ; SER_BAUD_50
86 .byte $02 ; SER_BAUD_75
87 .byte $03 ; SER_BAUD_110
88 .byte $04 ; SER_BAUD_134_5
89 .byte $05 ; SER_BAUD_150
90 .byte $06 ; SER_BAUD_300
91 .byte $07 ; SER_BAUD_600
92 .byte $08 ; SER_BAUD_1200
93 .byte $09 ; SER_BAUD_1800
94 .byte $0A ; SER_BAUD_2400
95 .byte $0B ; SER_BAUD_3600
96 .byte $0C ; SER_BAUD_4800
97 .byte $0D ; SER_BAUD_7200
98 .byte $0E ; SER_BAUD_9600
99 .byte $0F ; SER_BAUD_19200
100 .byte $FF ; SER_BAUD_38400
101 .byte $FF ; SER_BAUD_57600
102 .byte $FF ; SER_BAUD_115200
103 .byte $FF ; SER_BAUD_230400
106 .byte $60 ; SER_BITS_5
107 .byte $40 ; SER_BITS_6
108 .byte $20 ; SER_BITS_7
109 .byte $00 ; SER_BITS_8
112 .byte $00 ; SER_STOP_1
113 .byte $80 ; SER_STOP_2
116 .byte $00 ; SER_PAR_NONE
117 .byte $20 ; SER_PAR_ODD
118 .byte $60 ; SER_PAR_EVEN
119 .byte $A0 ; SER_PAR_MARK
120 .byte $E0 ; SER_PAR_SPACE
124 ;----------------------------------------------------------------------------
125 ; INSTALL routine. Is called after the driver is loaded into memory. If
126 ; possible, check if the hardware is present.
127 ; Must return an SER_ERR_xx code in a/x.
129 ; Since we don't have to manage the IRQ vector on the Plus/4, this is actually
132 ; UNINSTALL routine. Is called before the driver is removed from memory.
133 ; Must return an SER_ERR_xx code in a/x.
136 ; CLOSE: Close the port, disable interrupts and flush the buffer. Called
137 ; without parameters. Must return an error code in a/x.
144 ; Deactivate DTR and disable 6551 interrupts
149 ; Done, return an error code
155 ;----------------------------------------------------------------------------
156 ; PARAMS routine. A pointer to a ser_params structure is passed in ptr1.
157 ; Must return an SER_ERR_xx code in a/x.
161 ; Check if the handshake setting is valid
163 ldy #SER_PARAMS::HANDSHAKE ; Handshake
165 cmp #SER_HS_HW ; This is all we support
180 ; Set the value for the control register, which contains stop bits, word
181 ; length and the baud rate.
183 ldy #SER_PARAMS::BAUDRATE
184 lda (ptr1),y ; Baudrate index
186 lda BaudTable,y ; Get 6551 value
187 bmi InvBaud ; Branch if rate not supported
190 ldy #SER_PARAMS::DATABITS ; Databits
197 ldy #SER_PARAMS::STOPBITS ; Stopbits
202 ora #%00010000 ; Receiver clock source = baudrate
206 ; Set the value for the command register. We remember the base value in
207 ; RtsOff, since we will have to manipulate ACIA_CMD often.
209 ldy #SER_PARAMS::PARITY ; Parity
213 ora #%00000001 ; DTR active
215 ora #%00001000 ; Enable receive interrupts
227 lda #<SER_ERR_INIT_FAILED
228 ldx #>SER_ERR_INIT_FAILED
231 ; Baud rate not available
234 lda #<SER_ERR_BAUD_UNAVAIL
235 ldx #>SER_ERR_BAUD_UNAVAIL
238 ;----------------------------------------------------------------------------
239 ; GET: Will fetch a character from the receive buffer and store it into the
240 ; variable pointer to by ptr1. If no data is available, SER_ERR_NO_DATA is
244 GET: ldx SendFreeCnt ; Send data if necessary
250 ; Check for buffer empty
255 lda #<SER_ERR_NO_DATA
256 ldx #>SER_ERR_NO_DATA
259 ; Check for flow stopped & enough free: release flow control
271 ; Get byte from buffer
279 txa ; Return code = 0
282 ;----------------------------------------------------------------------------
283 ; PUT: Output character in A.
284 ; Must return an error code in a/x.
299 ; Put byte into send buffer & send
303 lda #<SER_ERR_OVERFLOW ; X is already zero
316 ;----------------------------------------------------------------------------
317 ; STATUS: Return the status in the variable pointed to by ptr1.
318 ; Must return an error code in a/x.
332 ;----------------------------------------------------------------------------
333 ; IOCTL: Driver defined entry point. The wrapper will pass a pointer to ioctl
334 ; specific data in ptr1, and the ioctl code in A.
335 ; Must return an error code in a/x.
338 IOCTL: lda #<SER_ERR_INV_IOCTL ; We don't support ioclts for now
339 ldx #>SER_ERR_INV_IOCTL
342 ;----------------------------------------------------------------------------
343 ; IRQ: Called from the builtin runtime IRQ handler as a subroutine. All
344 ; registers are already save, no parameters are passed, but the carry flag
345 ; is clear on entry. The routine must return with carry set if the interrupt
346 ; was handled, otherwise with carry clear.
350 sta IndReg ; Switch to the system bank
352 lda (acia),y ; Check ACIA status for receive interrupt
354 beq @L9 ; Jump if no ACIA interrupt (carry still clear)
356 lda (acia),y ; Get byte from ACIA
357 ldx RecvFreeCnt ; Check if we have free space left
358 beq @L1 ; Jump if no space in receive buffer
359 ldy RecvTail ; Load buffer pointer
360 sta RecvBuf,y ; Store received byte in buffer
361 inc RecvTail ; Increment buffer pointer
362 dec RecvFreeCnt ; Decrement free space counter
363 cpx #33 ; Check for buffer space low
364 bcs @L9 ; Assert flow control if buffer space low
366 ; Assert flow control if buffer space too low
372 sec ; Interrupt handled
374 ; Done, switch back to the execution segment
380 ;----------------------------------------------------------------------------
381 ; Try to send a byte. Internal routine. A = TryHard
385 sta tmp1 ; Remember tryHard flag
387 sta IndReg ; Switch to the system bank
392 ; Check for flow stopped
397 ; Check that swiftlink is ready to send
399 @L2: ldy #ACIA::STATUS
403 bit tmp1 ; Keep trying if must try hard
406 ; Switch back the bank and return
412 ; Send byte and try again
425 ;----------------------------------------------------------------------------
426 ; Write to the ACIA changing the indirect segment. Offset is in Y, value in A.