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
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 (may also use $A0F
72 ; and following in case of problems).
73 RecvHead := $A7 ; Head of receive buffer
74 RecvTail := $A8 ; Tail of receive buffer
75 RecvFreeCnt := $A9 ; Number of bytes in receive buffer
76 SendHead := $AA ; Head of send buffer
77 SendTail := $AB ; Tail of send buffer
78 SendFreeCnt := $B4 ; Number of bytes free in send buffer
79 Stopped := $B5 ; Flow-stopped flag
82 ; Send and receive buffers: 256 bytes each
83 RecvBuf := $0C00 ; Use the ROM buffers
88 ; Tables used to translate RS232 params into register values
90 BaudTable: ; bit7 = 1 means setting is invalid
91 .byte $FF ; SER_BAUD_45_5
92 .byte $FF ; SER_BAUD_50
93 .byte $FF ; SER_BAUD_75
94 .byte $FF ; SER_BAUD_110
95 .byte $FF ; SER_BAUD_134_5
96 .byte $02 ; SER_BAUD_150
97 .byte $05 ; SER_BAUD_300
98 .byte $06 ; SER_BAUD_600
99 .byte $07 ; SER_BAUD_1200
100 .byte $FF ; SER_BAUD_1800
101 .byte $08 ; SER_BAUD_2400
102 .byte $09 ; SER_BAUD_3600
103 .byte $0A ; SER_BAUD_4800
104 .byte $0B ; SER_BAUD_7200
105 .byte $0C ; SER_BAUD_9600
106 .byte $0E ; SER_BAUD_19200
107 .byte $0F ; SER_BAUD_38400
108 .byte $FF ; SER_BAUD_57600
109 .byte $FF ; SER_BAUD_115200
110 .byte $FF ; SER_BAUD_230400
113 .byte $60 ; SER_BITS_5
114 .byte $40 ; SER_BITS_6
115 .byte $20 ; SER_BITS_7
116 .byte $00 ; SER_BITS_8
119 .byte $00 ; SER_STOP_1
120 .byte $80 ; SER_STOP_2
123 .byte $00 ; SER_PAR_NONE
124 .byte $20 ; SER_PAR_ODD
125 .byte $60 ; SER_PAR_EVEN
126 .byte $A0 ; SER_PAR_MARK
127 .byte $E0 ; SER_PAR_SPACE
131 ;----------------------------------------------------------------------------
132 ; Interrupt stub that is copied into low RAM. The startup code uses a special
133 ; memory configuration with just kernal and I/O enabled (anything else is RAM).
134 ; The NMI handler in ROM will switch back to a configuration where just the
135 ; low 16K RAM are accessible. So we have to copy a smal piece of code into
136 ; low RAM that enables the cc65 configuration and then jumps to the real NMI
141 .org $1150 ; BASIC graphics area
144 lda #MMU_CFG_CC65 ; Bank 0 with kernal ROM...
145 sta MMU_CR ; ...enable
146 jsr NmiHandler ; Call the actual NMI handler
147 lda #$00 ; Get ROM config...
148 sta MMU_CR ; ...and enable it
150 .byte $4C ; Jump to the saved IRQ vector
155 ;----------------------------------------------------------------------------
156 ; INSTALL routine. Is called after the driver is loaded into memory. If
157 ; possible, check if the hardware is present.
158 ; Must return an SER_ERR_xx code in a/x.
162 ; Deactivate DTR and disable 6551 interrupts
167 ; Copy the NMI stub into low memory
169 ldy #.sizeof (NmiStub)-1
170 @L1: lda NmiStubOrig,y
175 ; Set up the nmi vector
179 sta NmiStub::Vector+0
180 sty NmiStub::Vector+1
186 ; Done, return an error code
192 ;----------------------------------------------------------------------------
193 ; UNINSTALL routine. Is called before the driver is removed from memory.
194 ; Must return an SER_ERR_xx code in a/x.
198 ; Stop interrupts, drop DTR
203 ; Restore NMI vector and return OK
205 lda NmiStub::Vector+0
206 ldy NmiStub::Vector+1
209 ;----------------------------------------------------------------------------
210 ; PARAMS routine. A pointer to a ser_params structure is passed in ptr1.
211 ; Must return an SER_ERR_xx code in a/x.
215 ; Check if the handshake setting is valid
217 ldy #SER_PARAMS::HANDSHAKE ; Handshake
219 cmp #SER_HS_HW ; This is all we support
226 ; Set the value for the control register, which contains stop bits, word
227 ; length and the baud rate.
229 ldy #SER_PARAMS::BAUDRATE
230 lda (ptr1),y ; Baudrate index
232 lda BaudTable,y ; Get 6551 value
233 bmi InvBaud ; Branch if rate not supported
236 ldy #SER_PARAMS::DATABITS ; Databits
243 ldy #SER_PARAMS::STOPBITS ; Stopbits
248 ora #%00010000 ; Receiver clock source = baudrate
251 ; Set the value for the command register. We remember the base value in
252 ; RtsOff, since we will have to manipulate ACIA_CMD often.
254 ldy #SER_PARAMS::PARITY ; Parity
258 ora #%00000001 ; DTR active
260 ora #%00001000 ; Enable receive interrupts
272 lda #<SER_ERR_INIT_FAILED
273 ldx #>SER_ERR_INIT_FAILED
276 ; Baud rate not available
279 lda #<SER_ERR_BAUD_UNAVAIL
280 ldx #>SER_ERR_BAUD_UNAVAIL
283 ;----------------------------------------------------------------------------
284 ; CLOSE: Close the port, disable interrupts and flush the buffer. Called
285 ; without parameters. Must return an error code in a/x.
290 ; Stop interrupts, drop DTR
295 ; Initalize buffers. Returns zero in a
305 ;----------------------------------------------------------------------------
306 ; GET: Will fetch a character from the receive buffer and store it into the
307 ; variable pointer to by ptr1. If no data is available, SER_ERR_NO_DATA is
311 GET: ldx SendFreeCnt ; Send data if necessary
317 ; Check for buffer empty
319 @L1: lda RecvFreeCnt ; (25)
322 lda #<SER_ERR_NO_DATA
323 ldx #>SER_ERR_NO_DATA
326 ; Check for flow stopped & enough free: release flow control
328 @L2: ldx Stopped ; (34)
338 ; Get byte from buffer
340 @L3: ldx RecvHead ; (41)
346 txa ; Return code = 0
349 ;----------------------------------------------------------------------------
350 ; PUT: Output character in A.
351 ; Must return an error code in a/x.
366 ; Put byte into send buffer & send
370 lda #<SER_ERR_OVERFLOW ; X is already zero
383 ;----------------------------------------------------------------------------
384 ; STATUS: Return the status in the variable pointed to by ptr1.
385 ; Must return an error code in a/x.
388 STATUS: lda ACIA_STATUS
394 ;----------------------------------------------------------------------------
395 ; IOCTL: Driver defined entry point. The wrapper will pass a pointer to ioctl
396 ; specific data in ptr1, and the ioctl code in A.
397 ; Must return an error code in a/x.
400 IOCTL: lda #<SER_ERR_INV_IOCTL ; We don't support ioclts for now
401 ldx #>SER_ERR_INV_IOCTL
404 ;----------------------------------------------------------------------------
405 ; IRQ: Not used on the C128
410 ;----------------------------------------------------------------------------
413 ; C128 NMI overhead=76 cycles: int=7, maxLatency=6, ROMenter=33, ROMexit=30
414 ; C64 NMI overhead=76 cycles: int=7, maxLatency=6, ROMenter=34, ROMexit=29
416 ; timing: normal=76+43+9=128 cycles, assertFlow=76+52+9=137 cycles
418 ; C128 @ 115.2k: 177 cycles avail (fast)
419 ; C64 @ 57.6k: 177 cycles avail, worstAvail=177-43? = 134
420 ; SCPU @ 230.4k: 868 cycles avail: for a joke!
422 ; Note: Because of the C128 banking, a small stub has to go into low memory,
423 ; since the ROM NMI entry point switches to a configuration, where only the
424 ; low 16K of RAM are visible. The entry code switches into the standard cc65
425 ; configuration (I/O + 16K kernal) and then jumps here. Registers are already
426 ; saved by the ROM code.
429 lda ACIA_STATUS ;(4) ;status ;check for byte received
433 lda ACIA_DATA ;(4) data ;get byte and put into receive buffer
436 beq @L9 ;(2*) Jump if no space in receive buffer
440 cpx #33 ;(2) check for buffer space low
444 ; Assert flow control
446 @L2: lda RtsOff ;(3) assert flow control if buffer space too low
447 sta ACIA_CMD ;(4) command
451 ;----------------------------------------------------------------------------
452 ; Try to send a byte. Internal routine. A = TryHard
456 sta tmp1 ; Remember tryHard flag
461 ; Check for flow stopped
466 ; Check that swiftlink is ready to send
471 bit tmp1 ;keep trying if must try hard
475 ; Send byte and try again
487 ;----------------------------------------------------------------------------