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|
;
; Serial driver for the Apple II Super Serial Card.
;
; Oliver Schmidt, 21.04.2005
;
; The driver is based on the cc65 rs232 module, which in turn is based on
; Craig Bruce device driver for the Switftlink/Turbo-232.
;
; SwiftLink/Turbo-232 v0.90 device driver, by Craig Bruce, 14-Apr-1998.
;
; This software is Public Domain. It is in Buddy assembler format.
;
; This device driver uses the SwiftLink RS-232 Serial Cartridge, available from
; Creative Micro Designs, Inc, and also supports the extensions of the Turbo232
; Serial Cartridge. Both devices are based on the 6551 ACIA chip. It also
; supports the "hacked" SwiftLink with a 1.8432 MHz crystal.
;
; The code assumes that the kernal + I/O are in context. On the C128, call
; it from Bank 15. On the C64, don't flip out the Kernal unless a suitable
; NMI catcher is put into the RAM under then Kernal. For the SuperCPU, the
; interrupt handling assumes that the 65816 is in 6502-emulation mode.
;
.include "zeropage.inc"
.include "ser-kernel.inc"
.include "ser-error.inc"
.macpack module
; ------------------------------------------------------------------------
; Header. Includes jump table
.ifdef __APPLE2ENH__
module_header _a2e_ssc_ser
.else
module_header _a2_ssc_ser
.endif
; Driver signature
.byte $73, $65, $72 ; "ser"
.byte SER_API_VERSION ; Serial API version number
; Library reference
.addr $0000
; Jump table
.addr SER_INSTALL
.addr SER_UNINSTALL
.addr SER_OPEN
.addr SER_CLOSE
.addr SER_GET
.addr SER_PUT
.addr SER_STATUS
.addr SER_IOCTL
.addr SER_IRQ
;----------------------------------------------------------------------------
; I/O definitions
ACIA = $C088
ACIA_DATA = ACIA+0 ; Data register
ACIA_STATUS = ACIA+1 ; Status register
ACIA_CMD = ACIA+2 ; Command register
ACIA_CTRL = ACIA+3 ; Control register
;----------------------------------------------------------------------------
; Global variables
.bss
RecvHead: .res 1 ; Head of receive buffer
RecvTail: .res 1 ; Tail of receive buffer
RecvFreeCnt: .res 1 ; Number of bytes in receive buffer
SendHead: .res 1 ; Head of send buffer
SendTail: .res 1 ; Tail of send buffer
SendFreeCnt: .res 1 ; Number of bytes in send buffer
Stopped: .res 1 ; Flow-stopped flag
RtsOff: .res 1 ;
RecvBuf: .res 256 ; Receive buffers: 256 bytes
SendBuf: .res 256 ; Send buffers: 256 bytes
Index: .res 1 ; I/O register index
.data
Slot: .byte $02 ; Default to SSC in slot 2
.rodata
; Tables used to translate RS232 params into register values
BaudTable: ; bit7 = 1 means setting is invalid
.byte $FF ; SER_BAUD_45_5
.byte $01 ; SER_BAUD_50
.byte $02 ; SER_BAUD_75
.byte $03 ; SER_BAUD_110
.byte $04 ; SER_BAUD_134_5
.byte $05 ; SER_BAUD_150
.byte $06 ; SER_BAUD_300
.byte $07 ; SER_BAUD_600
.byte $08 ; SER_BAUD_1200
.byte $09 ; SER_BAUD_1800
.byte $0A ; SER_BAUD_2400
.byte $0B ; SER_BAUD_3600
.byte $0C ; SER_BAUD_4800
.byte $0D ; SER_BAUD_7200
.byte $0E ; SER_BAUD_9600
.byte $0F ; SER_BAUD_19200
.byte $FF ; SER_BAUD_38400
.byte $FF ; SER_BAUD_57600
.byte $FF ; SER_BAUD_115200
.byte $FF ; SER_BAUD_230400
BitTable:
.byte $60 ; SER_BITS_5
.byte $40 ; SER_BITS_6
.byte $20 ; SER_BITS_7
.byte $00 ; SER_BITS_8
StopTable:
.byte $00 ; SER_STOP_1
.byte $80 ; SER_STOP_2
ParityTable:
.byte $00 ; SER_PAR_NONE
.byte $20 ; SER_PAR_ODD
.byte $60 ; SER_PAR_EVEN
.byte $A0 ; SER_PAR_MARK
.byte $E0 ; SER_PAR_SPACE
IdOfsTable:
.byte $05 ; Pascal 1.0 ID byte
.byte $07 ; Pascal 1.0 ID byte
.byte $0B ; Pascal 1.1 generic signature byte
.byte $0C ; Device signature byte
IdValTable:
.byte $38 ; Fixed
.byte $18 ; Fixed
.byte $01 ; Fixed
.byte $31 ; Serial or parallel I/O card type 1
IdTableLen = * - IdValTable
.code
;----------------------------------------------------------------------------
; SER_INSTALL: Is called after the driver is loaded into memory. If possible,
; check if the hardware is present. Must return an SER_ERR_xx code in a/x.
;
; Since we don't have to manage the IRQ vector on the Apple II, this is
; actually the same as:
;
; SER_UNINSTALL: Is called before the driver is removed from memory.
; No return code required (the driver is removed from memory on return).
;
; and:
;
; SER_CLOSE: Close the port and disable interrupts. Called without parameters.
; Must return an SER_ERR_xx code in a/x.
SER_INSTALL:
SER_UNINSTALL:
SER_CLOSE:
ldx Index ; Check for open port
beq :+
; Deactivate DTR and disable 6551 interrupts
lda #%00001010
sta ACIA_CMD,x
; Done, return an error code
: lda #<SER_ERR_OK
tax ; A is zero
stx Index ; Mark port as closed
rts
;----------------------------------------------------------------------------
; SER_OPEN: A pointer to a ser_params structure is passed in ptr1.
; Must return an SER_ERR_xx code in a/x.
SER_OPEN:
ldx #<$C000
stx ptr2
lda #>$C000
ora Slot
sta ptr2+1
; Check Pascal 1.1 Firmware Protocol ID bytes
: ldy IdOfsTable,x
lda IdValTable,x
cmp (ptr2),y
bne NoDevice
inx
cpx #IdTableLen
bcc :-
; Convert slot to I/O register index
lda Slot
asl
asl
asl
asl
tax
; Check if the handshake setting is valid
ldy #SER_PARAMS::HANDSHAKE ; Handshake
lda (ptr1),y
cmp #SER_HS_HW ; This is all we support
bne InvParam
; Initialize buffers
ldy #$00
sty Stopped
sty RecvHead
sty RecvTail
sty SendHead
sty SendTail
dey ; Y = 255
sty RecvFreeCnt
sty SendFreeCnt
; Set the value for the control register, which contains stop bits,
; word length and the baud rate.
ldy #SER_PARAMS::BAUDRATE
lda (ptr1),y ; Baudrate index
tay
lda BaudTable,y ; Get 6551 value
bmi InvBaud ; Branch if rate not supported
sta tmp1
ldy #SER_PARAMS::DATABITS ; Databits
lda (ptr1),y
tay
lda BitTable,y
ora tmp1
sta tmp1
ldy #SER_PARAMS::STOPBITS ; Stopbits
lda (ptr1),y
tay
lda StopTable,y
ora tmp1
ora #%00010000 ; Receiver clock source = baudrate
sta ACIA_CTRL,x
; Set the value for the command register. We remember the base value
; in RtsOff, since we will have to manipulate ACIA_CMD often.
ldy #SER_PARAMS::PARITY ; Parity
lda (ptr1),y
tay
lda ParityTable,y
ora #%00000001 ; DTR active
sta RtsOff
ora #%00001000 ; Enable receive interrupts
sta ACIA_CMD,x
; Done
stx Index ; Mark port as open
lda #<SER_ERR_OK
tax ; A is zero
rts
; Device (hardware) not found
NoDevice:lda #<SER_ERR_NO_DEVICE
ldx #>SER_ERR_NO_DEVICE
rts
; Invalid parameter
InvParam:lda #<SER_ERR_INIT_FAILED
ldx #>SER_ERR_INIT_FAILED
rts
; Baud rate not available
InvBaud:lda #<SER_ERR_BAUD_UNAVAIL
ldx #>SER_ERR_BAUD_UNAVAIL
rts
;----------------------------------------------------------------------------
; SER_GET: Will fetch a character from the receive buffer and store it into the
; variable pointed to by ptr1. If no data is available, SER_ERR_NO_DATA is
; returned.
SER_GET:
ldx Index
ldy SendFreeCnt ; Send data if necessary
iny ; Y == $FF?
beq :+
lda #$00 ; TryHard = false
jsr TryToSend
; Check for buffer empty
: lda RecvFreeCnt ; (25)
cmp #$FF
bne :+
lda #<SER_ERR_NO_DATA
ldx #>SER_ERR_NO_DATA
rts
; Check for flow stopped & enough free: release flow control
: ldy Stopped ; (34)
beq :+
cmp #63
bcc :+
lda #$00
sta Stopped
lda RtsOff
ora #%00001000
sta ACIA_CMD,x
; Get byte from buffer
: ldy RecvHead ; (41)
lda RecvBuf,y
inc RecvHead
inc RecvFreeCnt
ldx #$00 ; (59)
sta (ptr1,x)
txa ; Return code = 0
rts
;----------------------------------------------------------------------------
; SER_PUT: Output character in A.
; Must return an SER_ERR_xx code in a/x.
SER_PUT:
ldx Index
; Try to send
ldy SendFreeCnt
iny ; Y = $FF?
beq :+
pha
lda #$00 ; TryHard = false
jsr TryToSend
pla
; Put byte into send buffer & send
: ldy SendFreeCnt
bne :+
lda #<SER_ERR_OVERFLOW
ldx #>SER_ERR_OVERFLOW
rts
: ldy SendTail
sta SendBuf,y
inc SendTail
dec SendFreeCnt
lda #$FF ; TryHard = true
jsr TryToSend
lda #<SER_ERR_OK
tax
rts
;----------------------------------------------------------------------------
; SER_STATUS: Return the status in the variable pointed to by ptr1.
; Must return an SER_ERR_xx code in a/x.
SER_STATUS:
ldx Index
lda ACIA_STATUS,x
ldx #$00
sta (ptr1,x)
txa ; SER_ERR_OK
rts
;----------------------------------------------------------------------------
; SER_IOCTL: Driver defined entry point. The wrapper will pass a pointer to ioctl
; specific data in ptr1, and the ioctl code in A.
; Must return an SER_ERR_xx code in a/x.
SER_IOCTL:
; Check data msb and code to be 0
ora ptr1+1
bne :+
; Check data lsb to be [1..7]
ldx ptr1
beq :+
cpx #7+1
bcs :+
stx Slot
tax ; SER_ERR_OK
rts
: lda #<SER_ERR_INV_IOCTL
ldx #>SER_ERR_INV_IOCTL
rts
;----------------------------------------------------------------------------
; SER_IRQ: Called from the builtin runtime IRQ handler as a subroutine. All
; registers are already saved, no parameters are passed, but the carry flag
; is clear on entry. The routine must return with carry set if the interrupt
; was handled, otherwise with carry clear.
SER_IRQ:
ldx Index ; Check for open port
beq Done
lda ACIA_STATUS,x ; Check ACIA status for receive interrupt
and #$08
beq Done ; Jump if no ACIA interrupt
lda ACIA_DATA,x ; Get byte from ACIA
ldy RecvFreeCnt ; Check if we have free space left
beq Flow ; Jump if no space in receive buffer
ldy RecvTail ; Load buffer pointer
sta RecvBuf,y ; Store received byte in buffer
inc RecvTail ; Increment buffer pointer
dec RecvFreeCnt ; Decrement free space counter
ldy RecvFreeCnt ; Check for buffer space low
cpy #33
bcc Flow ; Assert flow control if buffer space low
rts ; Interrupt handled (carry already set)
; Assert flow control if buffer space too low
Flow: lda RtsOff
sta ACIA_CMD,x
sta Stopped
sec ; Interrupt handled
Done: rts
;----------------------------------------------------------------------------
; Try to send a byte. Internal routine. A = TryHard
TryToSend:
sta tmp1 ; Remember tryHard flag
Again: lda SendFreeCnt
cmp #$FF
beq Quit ; Bail out
; Check for flow stopped
lda Stopped
bne Quit ; Bail out
; Check that ACIA is ready to send
lda ACIA_STATUS,x
and #$10
bne Send
bit tmp1 ; Keep trying if must try hard
bmi Again
Quit: rts
; Send byte and try again
Send: ldy SendHead
lda SendBuf,y
sta ACIA_DATA,x
inc SendHead
inc SendFreeCnt
jmp Again
|
