2 ; Serial driver for the C128 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
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 ;----------------------------------------------------------------------------
66 ; We reuse the RS232 zero page variables for the driver, since the ROM
67 ; routines cannot be used together with this driver (may also use $A0F
68 ; and following in case of problems).
69 RecvHead := $A7 ; Head of receive buffer
70 RecvTail := $A8 ; Tail of receive buffer
71 RecvFreeCnt := $A9 ; Number of bytes in receive buffer
72 SendHead := $AA ; Head of send buffer
73 SendTail := $AB ; Tail of send buffer
74 SendFreeCnt := $B4 ; Number of bytes free in send buffer
75 Stopped := $B5 ; Flow-stopped flag
78 ; Send and receive buffers: 256 bytes each
79 RecvBuf := $0C00 ; Use the ROM buffers
84 ; Tables used to translate RS232 params into register values
86 BaudTable: ; bit7 = 1 means setting is invalid
87 .byte $FF ; SER_BAUD_45_5
88 .byte $FF ; SER_BAUD_50
89 .byte $FF ; SER_BAUD_75
90 .byte $FF ; SER_BAUD_110
91 .byte $FF ; SER_BAUD_134_5
92 .byte $02 ; SER_BAUD_150
93 .byte $05 ; SER_BAUD_300
94 .byte $06 ; SER_BAUD_600
95 .byte $07 ; SER_BAUD_1200
96 .byte $FF ; SER_BAUD_1800
97 .byte $08 ; SER_BAUD_2400
98 .byte $09 ; SER_BAUD_3600
99 .byte $0A ; SER_BAUD_4800
100 .byte $0B ; SER_BAUD_7200
101 .byte $0C ; SER_BAUD_9600
102 .byte $0E ; SER_BAUD_19200
103 .byte $0F ; SER_BAUD_38400
104 .byte $FF ; SER_BAUD_57600
105 .byte $FF ; SER_BAUD_115200
106 .byte $FF ; SER_BAUD_230400
109 .byte $60 ; SER_BITS_5
110 .byte $40 ; SER_BITS_6
111 .byte $20 ; SER_BITS_7
112 .byte $00 ; SER_BITS_8
115 .byte $00 ; SER_STOP_1
116 .byte $80 ; SER_STOP_2
119 .byte $00 ; SER_PAR_NONE
120 .byte $20 ; SER_PAR_ODD
121 .byte $60 ; SER_PAR_EVEN
122 .byte $A0 ; SER_PAR_MARK
123 .byte $E0 ; SER_PAR_SPACE
127 ;----------------------------------------------------------------------------
128 ; Interrupt stub that is copied into low RAM. The startup code uses a special
129 ; memory configuration with just kernal and I/O enabled (anything else is RAM).
130 ; The NMI handler in ROM will switch back to a configuration where just the
131 ; low 16K RAM are accessible. So we have to copy a smal piece of code into
132 ; low RAM that enables the cc65 configuration and then jumps to the real NMI
137 .org $1150 ; BASIC graphics area
140 lda #MMU_CFG_CC65 ; Bank 0 with kernal ROM...
141 sta MMU_CR ; ...enable
142 jsr NmiHandler ; Call the actual NMI handler
143 lda #$00 ; Get ROM config...
144 sta MMU_CR ; ...and enable it
146 .byte $4C ; Jump to the saved IRQ vector
151 ;----------------------------------------------------------------------------
152 ; INSTALL routine. Is called after the driver is loaded into memory. If
153 ; possible, check if the hardware is present.
154 ; Must return an SER_ERR_xx code in a/x.
158 ; Deactivate DTR and disable 6551 interrupts
163 ; Copy the NMI stub into low memory
165 ldy #.sizeof (NmiStub)-1
166 @L1: lda NmiStubOrig,y
171 ; Set up the nmi vector
175 sta NmiStub::Vector+0
176 sty NmiStub::Vector+1
182 ; Done, return an error code
188 ;----------------------------------------------------------------------------
189 ; UNINSTALL routine. Is called before the driver is removed from memory.
190 ; Must return an SER_ERR_xx code in a/x.
194 ; Stop interrupts, drop DTR
199 ; Restore NMI vector and return OK
201 lda NmiStub::Vector+0
202 ldy NmiStub::Vector+1
205 ;----------------------------------------------------------------------------
206 ; PARAMS routine. A pointer to a ser_params structure is passed in ptr1.
207 ; Must return an SER_ERR_xx code in a/x.
211 ; Check if the handshake setting is valid
213 ldy #SER_PARAMS::HANDSHAKE ; Handshake
215 cmp #SER_HS_HW ; This is all we support
222 ; Set the value for the control register, which contains stop bits, word
223 ; length and the baud rate.
225 ldy #SER_PARAMS::BAUDRATE
226 lda (ptr1),y ; Baudrate index
228 lda BaudTable,y ; Get 6551 value
229 bmi InvBaud ; Branch if rate not supported
232 ldy #SER_PARAMS::DATABITS ; Databits
239 ldy #SER_PARAMS::STOPBITS ; Stopbits
244 ora #%00010000 ; Receiver clock source = baudrate
247 ; Set the value for the command register. We remember the base value in
248 ; RtsOff, since we will have to manipulate ACIA_CMD often.
250 ldy #SER_PARAMS::PARITY ; Parity
254 ora #%00000001 ; DTR active
256 ora #%00001000 ; Enable receive interrupts
268 lda #<SER_ERR_INIT_FAILED
269 ldx #>SER_ERR_INIT_FAILED
272 ; Baud rate not available
275 lda #<SER_ERR_BAUD_UNAVAIL
276 ldx #>SER_ERR_BAUD_UNAVAIL
279 ;----------------------------------------------------------------------------
280 ; CLOSE: Close the port, disable interrupts and flush the buffer. Called
281 ; without parameters. Must return an error code in a/x.
286 ; Stop interrupts, drop DTR
291 ; Initalize buffers. Returns zero in a
301 ;----------------------------------------------------------------------------
302 ; GET: Will fetch a character from the receive buffer and store it into the
303 ; variable pointer to by ptr1. If no data is available, SER_ERR_NO_DATA is
307 GET: ldx SendFreeCnt ; Send data if necessary
313 ; Check for buffer empty
315 @L1: lda RecvFreeCnt ; (25)
318 lda #<SER_ERR_NO_DATA
319 ldx #>SER_ERR_NO_DATA
322 ; Check for flow stopped & enough free: release flow control
324 @L2: ldx Stopped ; (34)
334 ; Get byte from buffer
336 @L3: ldx RecvHead ; (41)
342 txa ; Return code = 0
345 ;----------------------------------------------------------------------------
346 ; PUT: Output character in A.
347 ; Must return an error code in a/x.
362 ; Put byte into send buffer & send
366 lda #<SER_ERR_OVERFLOW ; X is already zero
379 ;----------------------------------------------------------------------------
380 ; STATUS: Return the status in the variable pointed to by ptr1.
381 ; Must return an error code in a/x.
384 STATUS: lda ACIA_STATUS
390 ;----------------------------------------------------------------------------
391 ; IOCTL: Driver defined entry point. The wrapper will pass a pointer to ioctl
392 ; specific data in ptr1, and the ioctl code in A.
393 ; Must return an error code in a/x.
396 IOCTL: lda #<SER_ERR_INV_IOCTL ; We don't support ioclts for now
397 ldx #>SER_ERR_INV_IOCTL
400 ;----------------------------------------------------------------------------
401 ; IRQ: Not used on the C128
406 ;----------------------------------------------------------------------------
409 ; C128 NMI overhead=76 cycles: int=7, maxLatency=6, ROMenter=33, ROMexit=30
410 ; C64 NMI overhead=76 cycles: int=7, maxLatency=6, ROMenter=34, ROMexit=29
412 ; timing: normal=76+43+9=128 cycles, assertFlow=76+52+9=137 cycles
414 ; C128 @ 115.2k: 177 cycles avail (fast)
415 ; C64 @ 57.6k: 177 cycles avail, worstAvail=177-43? = 134
416 ; SCPU @ 230.4k: 868 cycles avail: for a joke!
418 ; Note: Because of the C128 banking, a small stub has to go into low memory,
419 ; since the ROM NMI entry point switches to a configuration, where only the
420 ; low 16K of RAM are visible. The entry code switches into the standard cc65
421 ; configuration (I/O + 16K kernal) and then jumps here. Registers are already
422 ; saved by the ROM code.
425 lda ACIA_STATUS ;(4) ;status ;check for byte received
429 lda ACIA_DATA ;(4) data ;get byte and put into receive buffer
432 beq @L9 ;(2*) Jump if no space in receive buffer
436 cpx #33 ;(2) check for buffer space low
440 ; Assert flow control
442 @L2: lda RtsOff ;(3) assert flow control if buffer space too low
443 sta ACIA_CMD ;(4) command
447 ;----------------------------------------------------------------------------
448 ; Try to send a byte. Internal routine. A = TryHard
452 sta tmp1 ; Remember tryHard flag
457 ; Check for flow stopped
462 ; Check that swiftlink is ready to send
467 bit tmp1 ;keep trying if must try hard
471 ; Send byte and try again
483 ;----------------------------------------------------------------------------