2 ; Serial driver for the C64 using a Swiftlink or Turbo-232 cartridge.
4 ; Ullrich von Bassewitz, 2003-04-18
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 "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 ;----------------------------------------------------------------------------
70 ; We reuse the RS232 zero page variables for the driver, since the ROM
71 ; routines cannot be used together with this driver.
72 RecvHead = $B5 ; Head of receive buffer
73 RecvTail = $BD ; Tail of receive buffer
74 RecvFreeCnt = $F7 ; Number of bytes in receive buffer
75 SendHead = $F8 ; Head of send buffer
76 SendTail = $F9 ; Tail of send buffer
77 SendFreeCnt = $FA ; Number of bytes free in send buffer
80 Stopped: .res 1 ; Flow-stopped flag
83 ; Send and receive buffers: 256 bytes each
88 NmiContinue: .byte $4c ; JMP instruction for NMI save -- continue
89 NmiSave: .res 2 ; normal NMI handler
93 ; Tables used to translate RS232 params into register values
95 BaudTable: ; bit7 = 1 means setting is invalid
96 .byte $FF ; SER_BAUD_45_5
97 .byte $FF ; SER_BAUD_50
98 .byte $FF ; SER_BAUD_75
99 .byte $FF ; SER_BAUD_110
100 .byte $FF ; SER_BAUD_134_5
101 .byte $02 ; SER_BAUD_150
102 .byte $05 ; SER_BAUD_300
103 .byte $06 ; SER_BAUD_600
104 .byte $07 ; SER_BAUD_1200
105 .byte $FF ; SER_BAUD_1800
106 .byte $08 ; SER_BAUD_2400
107 .byte $09 ; SER_BAUD_3600
108 .byte $0A ; SER_BAUD_4800
109 .byte $0B ; SER_BAUD_7200
110 .byte $0C ; SER_BAUD_9600
111 .byte $0E ; SER_BAUD_19200
112 .byte $0F ; SER_BAUD_38400
113 .byte $FF ; SER_BAUD_57600
114 .byte $FF ; SER_BAUD_115200
115 .byte $FF ; SER_BAUD_230400
118 .byte $60 ; SER_BITS_5
119 .byte $40 ; SER_BITS_6
120 .byte $20 ; SER_BITS_7
121 .byte $00 ; SER_BITS_8
124 .byte $00 ; SER_STOP_1
125 .byte $80 ; SER_STOP_2
128 .byte $00 ; SER_PAR_NONE
129 .byte $20 ; SER_PAR_ODD
130 .byte $60 ; SER_PAR_EVEN
131 .byte $A0 ; SER_PAR_MARK
132 .byte $E0 ; SER_PAR_SPACE
136 ;----------------------------------------------------------------------------
137 ; INSTALL routine. Is called after the driver is loaded into memory. If
138 ; possible, check if the hardware is present.
139 ; Must return an SER_ERR_xx code in a/x.
143 ; Deactivate DTR and disable 6551 interrupts
148 ; Set up the nmi vector
159 ; Done, return an error code
165 ;----------------------------------------------------------------------------
166 ; UNINSTALL routine. Is called before the driver is removed from memory.
167 ; Must return an SER_ERR_xx code in a/x.
171 ; Stop interrupts, drop DTR
176 ; Restore NMI vector and return OK
182 ;----------------------------------------------------------------------------
183 ; PARAMS routine. A pointer to a ser_params structure is passed in ptr1.
184 ; Must return an SER_ERR_xx code in a/x.
188 ; Check if the handshake setting is valid
190 ldy #SER_PARAMS::HANDSHAKE ; Handshake
192 cmp #SER_HS_HW ; This is all we support
199 ; Set the value for the control register, which contains stop bits, word
200 ; length and the baud rate.
202 ldy #SER_PARAMS::BAUDRATE
203 lda (ptr1),y ; Baudrate index
205 lda BaudTable,y ; Get 6551 value
206 bmi InvBaud ; Branch if rate not supported
209 ldy #SER_PARAMS::DATABITS ; Databits
216 ldy #SER_PARAMS::STOPBITS ; Stopbits
221 ora #%00010000 ; Receiver clock source = baudrate
224 ; Set the value for the command register. We remember the base value in
225 ; RtsOff, since we will have to manipulate ACIA_CMD often.
227 ldy #SER_PARAMS::PARITY ; Parity
231 ora #%00000001 ; DTR active
233 ora #%00001000 ; Enable receive interrupts
245 lda #<SER_ERR_INIT_FAILED
246 ldx #>SER_ERR_INIT_FAILED
249 ; Baud rate not available
252 lda #<SER_ERR_BAUD_UNAVAIL
253 ldx #>SER_ERR_BAUD_UNAVAIL
256 ;----------------------------------------------------------------------------
257 ; CLOSE: Close the port, disable interrupts and flush the buffer. Called
258 ; without parameters. Must return an error code in a/x.
263 ; Stop interrupts, drop DTR
268 ; Initalize buffers. Returns zero in a
278 ;----------------------------------------------------------------------------
279 ; GET: Will fetch a character from the receive buffer and store it into the
280 ; variable pointer to by ptr1. If no data is available, SER_ERR_NO_DATA is
284 GET: ldx SendFreeCnt ; Send data if necessary
290 ; Check for buffer empty
292 @L1: lda RecvFreeCnt ; (25)
295 lda #<SER_ERR_NO_DATA
296 ldx #>SER_ERR_NO_DATA
299 ; Check for flow stopped & enough free: release flow control
301 @L2: ldx Stopped ; (34)
311 ; Get byte from buffer
313 @L3: ldx RecvHead ; (41)
319 txa ; Return code = 0
322 ;----------------------------------------------------------------------------
323 ; PUT: Output character in A.
324 ; Must return an error code in a/x.
339 ; Put byte into send buffer & send
343 lda #<SER_ERR_OVERFLOW ; X is already zero
356 ;----------------------------------------------------------------------------
357 ; STATUS: Return the status in the variable pointed to by ptr1.
358 ; Must return an error code in a/x.
361 STATUS: lda ACIA_STATUS
367 ;----------------------------------------------------------------------------
368 ; IOCTL: Driver defined entry point. The wrapper will pass a pointer to ioctl
369 ; specific data in ptr1, and the ioctl code in A.
370 ; Must return an error code in a/x.
373 IOCTL: lda #<SER_ERR_INV_IOCTL ; We don't support ioclts for now
374 ldx #>SER_ERR_INV_IOCTL
377 ;----------------------------------------------------------------------------
378 ; IRQ: Not used on the C64
383 ;----------------------------------------------------------------------------
386 ; C128 NMI overhead=76 cycles: int=7, maxLatency=6, ROMenter=33, ROMexit=30
387 ; C64 NMI overhead=76 cycles: int=7, maxLatency=6, ROMenter=34, ROMexit=29
389 ; timing: normal=76+43+9=128 cycles, assertFlow=76+52+9=137 cycles
391 ; C128 @ 115.2k: 177 cycles avail (fast)
392 ; C64 @ 57.6k: 177 cycles avail, worstAvail=177-43? = 134
393 ; SCPU @ 230.4k: 868 cycles avail: for a joke!
398 lda ACIA_STATUS ;(4) ;status ;check for byte received
406 @L1: lda ACIA_DATA ;(4) data ;get byte and put into receive buffer
409 beq @L3 ;(2*) Jump if no space in receive buffer
413 cpx #33 ;(2) check for buffer space low
417 ; Assert flow control
419 @L2: lda RtsOff ;(3) assert flow control if buffer space too low
420 sta ACIA_CMD ;(4) command
422 @L3: jmp NMIEXIT ;(3)
427 ;----------------------------------------------------------------------------
428 ; Try to send a byte. Internal routine. A = TryHard
432 sta tmp1 ; Remember tryHard flag
437 ; Check for flow stopped
442 ; Check that swiftlink is ready to send
447 bit tmp1 ;keep trying if must try hard
451 ; Send byte and try again
463 ;----------------------------------------------------------------------------