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"
32 ; ------------------------------------------------------------------------
33 ; Header. Includes jump table
35 module_header _c128_swlink_ser
39 .byte $73, $65, $72 ; "ser"
40 .byte SER_API_VERSION ; Serial API version number
58 ;----------------------------------------------------------------------------
62 ACIA_DATA = ACIA+0 ; Data register
63 ACIA_STATUS = ACIA+1 ; Status register
64 ACIA_CMD = ACIA+2 ; Command register
65 ACIA_CTRL = ACIA+3 ; Control register
67 ;----------------------------------------------------------------------------
72 ; We reuse the RS232 zero page variables for the driver, since the ROM
73 ; routines cannot be used together with this driver (may also use $A0F
74 ; and following in case of problems).
75 RecvHead := $A7 ; Head of receive buffer
76 RecvTail := $A8 ; Tail of receive buffer
77 RecvFreeCnt := $A9 ; Number of bytes in receive buffer
78 SendHead := $AA ; Head of send buffer
79 SendTail := $AB ; Tail of send buffer
80 SendFreeCnt := $B4 ; Number of bytes free in send buffer
81 Stopped := $B5 ; Flow-stopped flag
84 ; Send and receive buffers: 256 bytes each
85 RecvBuf := $0C00 ; Use the ROM buffers
90 ; Tables used to translate RS232 params into register values
92 BaudTable: ; bit7 = 1 means setting is invalid
93 .byte $FF ; SER_BAUD_45_5
94 .byte $FF ; SER_BAUD_50
95 .byte $FF ; SER_BAUD_75
96 .byte $FF ; SER_BAUD_110
97 .byte $FF ; SER_BAUD_134_5
98 .byte $02 ; SER_BAUD_150
99 .byte $05 ; SER_BAUD_300
100 .byte $06 ; SER_BAUD_600
101 .byte $07 ; SER_BAUD_1200
102 .byte $FF ; SER_BAUD_1800
103 .byte $08 ; SER_BAUD_2400
104 .byte $09 ; SER_BAUD_3600
105 .byte $0A ; SER_BAUD_4800
106 .byte $0B ; SER_BAUD_7200
107 .byte $0C ; SER_BAUD_9600
108 .byte $0E ; SER_BAUD_19200
109 .byte $0F ; SER_BAUD_38400
110 .byte $FF ; SER_BAUD_57600
111 .byte $FF ; SER_BAUD_115200
112 .byte $FF ; SER_BAUD_230400
115 .byte $60 ; SER_BITS_5
116 .byte $40 ; SER_BITS_6
117 .byte $20 ; SER_BITS_7
118 .byte $00 ; SER_BITS_8
121 .byte $00 ; SER_STOP_1
122 .byte $80 ; SER_STOP_2
125 .byte $00 ; SER_PAR_NONE
126 .byte $20 ; SER_PAR_ODD
127 .byte $60 ; SER_PAR_EVEN
128 .byte $A0 ; SER_PAR_MARK
129 .byte $E0 ; SER_PAR_SPACE
133 ;----------------------------------------------------------------------------
134 ; Interrupt stub that is copied into low RAM. The startup code uses a special
135 ; memory configuration with just kernal and I/O enabled (anything else is RAM).
136 ; The NMI handler in ROM will switch back to a configuration where just the
137 ; low 16K RAM are accessible. So we have to copy a smal piece of code into
138 ; low RAM that enables the cc65 configuration and then jumps to the real NMI
143 .org $1150 ; BASIC graphics area
146 lda #MMU_CFG_CC65 ; Bank 0 with kernal ROM...
147 sta MMU_CR ; ...enable
148 jsr NmiHandler ; Call the actual NMI handler
149 lda #$00 ; Get ROM config...
150 sta MMU_CR ; ...and enable it
152 .byte $4C ; Jump to the saved IRQ vector
157 ;----------------------------------------------------------------------------
158 ; INSTALL routine. Is called after the driver is loaded into memory. If
159 ; possible, check if the hardware is present.
160 ; Must return an SER_ERR_xx code in a/x.
164 ; Deactivate DTR and disable 6551 interrupts
169 ; Copy the NMI stub into low memory
171 ldy #.sizeof (NmiStub)-1
172 @L1: lda NmiStubOrig,y
177 ; Set up the nmi vector
181 sta NmiStub::Vector+0
182 sty NmiStub::Vector+1
188 ; Done, return an error code
194 ;----------------------------------------------------------------------------
195 ; UNINSTALL routine. Is called before the driver is removed from memory.
196 ; Must return an SER_ERR_xx code in a/x.
200 ; Stop interrupts, drop DTR
205 ; Restore NMI vector and return OK
207 lda NmiStub::Vector+0
208 ldy NmiStub::Vector+1
211 ;----------------------------------------------------------------------------
212 ; PARAMS routine. A pointer to a ser_params structure is passed in ptr1.
213 ; Must return an SER_ERR_xx code in a/x.
217 ; Check if the handshake setting is valid
219 ldy #SER_PARAMS::HANDSHAKE ; Handshake
221 cmp #SER_HS_HW ; This is all we support
228 ; Set the value for the control register, which contains stop bits, word
229 ; length and the baud rate.
231 ldy #SER_PARAMS::BAUDRATE
232 lda (ptr1),y ; Baudrate index
234 lda BaudTable,y ; Get 6551 value
235 bmi InvBaud ; Branch if rate not supported
238 ldy #SER_PARAMS::DATABITS ; Databits
245 ldy #SER_PARAMS::STOPBITS ; Stopbits
250 ora #%00010000 ; Receiver clock source = baudrate
253 ; Set the value for the command register. We remember the base value in
254 ; RtsOff, since we will have to manipulate ACIA_CMD often.
256 ldy #SER_PARAMS::PARITY ; Parity
260 ora #%00000001 ; DTR active
262 ora #%00001000 ; Enable receive interrupts
274 lda #<SER_ERR_INIT_FAILED
275 ldx #>SER_ERR_INIT_FAILED
278 ; Baud rate not available
281 lda #<SER_ERR_BAUD_UNAVAIL
282 ldx #>SER_ERR_BAUD_UNAVAIL
285 ;----------------------------------------------------------------------------
286 ; CLOSE: Close the port, disable interrupts and flush the buffer. Called
287 ; without parameters. Must return an error code in a/x.
292 ; Stop interrupts, drop DTR
297 ; Initalize buffers. Returns zero in a
307 ;----------------------------------------------------------------------------
308 ; GET: Will fetch a character from the receive buffer and store it into the
309 ; variable pointer to by ptr1. If no data is available, SER_ERR_NO_DATA is
313 GET: ldx SendFreeCnt ; Send data if necessary
319 ; Check for buffer empty
321 @L1: lda RecvFreeCnt ; (25)
324 lda #<SER_ERR_NO_DATA
325 ldx #>SER_ERR_NO_DATA
328 ; Check for flow stopped & enough free: release flow control
330 @L2: ldx Stopped ; (34)
340 ; Get byte from buffer
342 @L3: ldx RecvHead ; (41)
348 txa ; Return code = 0
351 ;----------------------------------------------------------------------------
352 ; PUT: Output character in A.
353 ; Must return an error code in a/x.
368 ; Put byte into send buffer & send
372 lda #<SER_ERR_OVERFLOW ; X is already zero
385 ;----------------------------------------------------------------------------
386 ; STATUS: Return the status in the variable pointed to by ptr1.
387 ; Must return an error code in a/x.
390 STATUS: lda ACIA_STATUS
396 ;----------------------------------------------------------------------------
397 ; IOCTL: Driver defined entry point. The wrapper will pass a pointer to ioctl
398 ; specific data in ptr1, and the ioctl code in A.
399 ; Must return an error code in a/x.
402 IOCTL: lda #<SER_ERR_INV_IOCTL ; We don't support ioclts for now
403 ldx #>SER_ERR_INV_IOCTL
406 ;----------------------------------------------------------------------------
407 ; IRQ: Not used on the C128
412 ;----------------------------------------------------------------------------
415 ; C128 NMI overhead=76 cycles: int=7, maxLatency=6, ROMenter=33, ROMexit=30
416 ; C64 NMI overhead=76 cycles: int=7, maxLatency=6, ROMenter=34, ROMexit=29
418 ; timing: normal=76+43+9=128 cycles, assertFlow=76+52+9=137 cycles
420 ; C128 @ 115.2k: 177 cycles avail (fast)
421 ; C64 @ 57.6k: 177 cycles avail, worstAvail=177-43? = 134
422 ; SCPU @ 230.4k: 868 cycles avail: for a joke!
424 ; Note: Because of the C128 banking, a small stub has to go into low memory,
425 ; since the ROM NMI entry point switches to a configuration, where only the
426 ; low 16K of RAM are visible. The entry code switches into the standard cc65
427 ; configuration (I/O + 16K kernal) and then jumps here. Registers are already
428 ; saved by the ROM code.
431 lda ACIA_STATUS ;(4) ;status ;check for byte received
435 lda ACIA_DATA ;(4) data ;get byte and put into receive buffer
438 beq @L9 ;(2*) Jump if no space in receive buffer
442 cpx #33 ;(2) check for buffer space low
446 ; Assert flow control
448 @L2: lda RtsOff ;(3) assert flow control if buffer space too low
449 sta ACIA_CMD ;(4) command
453 ;----------------------------------------------------------------------------
454 ; Try to send a byte. Internal routine. A = TryHard
458 sta tmp1 ; Remember tryHard flag
463 ; Check for flow stopped
468 ; Check that swiftlink is ready to send
473 bit tmp1 ;keep trying if must try hard
477 ; Send byte and try again
489 ;----------------------------------------------------------------------------