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cc65/libsrc/cbm610/cbm610-stdser.s
cuz a7042ddbe4 Complete redesign of the CBM610 support.
Use wrappers to call the kernal in bank 15 instead of implementing kernal
functionality within the cc65 libs (eats performance but is much smaller and
simpler).
Improved startup/shutdown code allows a return to the system bank without
calling the BASIC cold start vector.


git-svn-id: svn://svn.cc65.org/cc65/trunk@2793 b7a2c559-68d2-44c3-8de9-860c34a00d81
2003-12-20 23:13:26 +00:00

455 lines
12 KiB
ArmAsm

;
; Serial driver for the builtin 6551 ACIA of the Commodore 610.
;
; Ullrich von Bassewitz, 2003-12-18
;
; 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 "extzp.inc"
.include "ser-kernel.inc"
.include "ser-error.inc"
.include "cbm610.inc"
; ------------------------------------------------------------------------
; Header. Includes jump table
.segment "JUMPTABLE"
; Driver signature
.byte $73, $65, $72 ; "ser"
.byte SER_API_VERSION ; Serial API version number
; Jump table.
.word INSTALL
.word UNINSTALL
.word OPEN
.word CLOSE
.word GET
.word PUT
.word STATUS
.word IOCTL
.word IRQ
;----------------------------------------------------------------------------
;
; 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 ;
; Send and receive buffers: 256 bytes each
RecvBuf: .res 256
SendBuf: .res 256
.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
.code
;----------------------------------------------------------------------------
; INSTALL routine. 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 Plus/4, this is actually
; the same as:
;
; UNINSTALL routine. Is called before the driver is removed from memory.
; Must return an SER_ERR_xx code in a/x.
INSTALL:
UNINSTALL:
; Deactivate DTR and disable 6551 interrupts
lda #%00001010
jsr write_cmd
; Done, return an error code
lda #<SER_ERR_OK
tax ; A is zero
rts
;----------------------------------------------------------------------------
; PARAMS routine. A pointer to a ser_params structure is passed in ptr1.
; Must return an SER_ERR_xx code in a/x.
OPEN:
; 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
jsr InitBuffers
; 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
ldy #ACIA::CTRL
jsr write
; 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
jsr write_cmd
; Done
lda #<SER_ERR_OK
tax ; A is zero
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
;----------------------------------------------------------------------------
; CLOSE: Close the port, disable interrupts and flush the buffer. Called
; without parameters. Must return an error code in a/x.
;
CLOSE:
; Stop interrupts, drop DTR
lda #%00001010
jsr write_cmd
; Initalize buffers.
jsr InitBuffers
; Return OK
lda #<SER_ERR_OK
tax ; A is zero
rts
;----------------------------------------------------------------------------
; GET: Will fetch a character from the receive buffer and store it into the
; variable pointer to by ptr1. If no data is available, SER_ERR_NO_DATA is
; return.
;
GET: ldx SendFreeCnt ; Send data if necessary
inx ; X == $FF?
beq @L1
lda #$00
jsr TryToSend
; Check for buffer empty
@L1: lda RecvFreeCnt
cmp #$ff
bne @L2
lda #<SER_ERR_NO_DATA
ldx #>SER_ERR_NO_DATA
rts
; Check for flow stopped & enough free: release flow control
@L2: ldx Stopped
beq @L3
cmp #63
bcc @L3
lda #$00
sta Stopped
lda RtsOff
ora #%00001000
jsr write_cmd
; Get byte from buffer
@L3: ldx RecvHead
lda RecvBuf,x
inc RecvHead
inc RecvFreeCnt
ldx #$00
sta (ptr1,x)
txa ; Return code = 0
rts
;----------------------------------------------------------------------------
; PUT: Output character in A.
; Must return an error code in a/x.
;
PUT:
; Try to send
ldx SendFreeCnt
inx ; X = $ff?
beq @L2
pha
lda #$00
jsr TryToSend
pla
; Put byte into send buffer & send
@L2: ldx SendFreeCnt
bne @L3
lda #<SER_ERR_OVERFLOW ; X is already zero
rts
@L3: ldx SendTail
sta SendBuf,x
inc SendTail
dec SendFreeCnt
lda #$ff
jsr TryToSend
lda #<SER_ERR_OK
tax
rts
;----------------------------------------------------------------------------
; STATUS: Return the status in the variable pointed to by ptr1.
; Must return an error code in a/x.
;
STATUS: lda #$0F
sta IndReg
ldy #ACIA::STATUS
lda (acia),y
ldx #0
sta (ptr1,x)
lda IndReg
sta ExecReg
txa ; SER_ERR_OK
rts
;----------------------------------------------------------------------------
; 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 error code in a/x.
;
IOCTL: lda #<SER_ERR_INV_IOCTL ; We don't support ioclts for now
ldx #>SER_ERR_INV_IOCTL
rts
;----------------------------------------------------------------------------
; IRQ: Called from the builtin runtime IRQ handler as a subroutine. All
; registers are already save, no parameters are passed and no return code
; is expected.
;
IRQ: lda #$0F
sta IndReg ; Switch to the system bank
ldy #ACIA::STATUS
lda (acia),y ; Check ACIA status for receive interrupt
and #$08
beq @L9 ; Jump if no ACIA interrupt
ldy #ACIA::DATA
lda (acia),y ; Get byte from ACIA
ldx RecvFreeCnt ; Check if we have free space left
beq @L1 ; 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
cpx #33 ; Check for buffer space low
bcs @L9 ; Assert flow control if buffer space low
; Assert flow control if buffer space too low
@L1: lda RtsOff
ldy #ACIA::CMD
sta (acia),y
sta Stopped
; Done, switch back to the execution segment
@L9: lda ExecReg
sta IndReg
rts
;----------------------------------------------------------------------------
; Try to send a byte. Internal routine. A = TryHard
.proc TryToSend
sta tmp1 ; Remember tryHard flag
lda #$0F
sta IndReg ; Switch to the system bank
@L0: lda SendFreeCnt
cmp #$ff
beq @L3 ; Bail out
; Check for flow stopped
@L1: lda Stopped
bne @L3 ; Bail out
; Check that swiftlink is ready to send
@L2: ldy #ACIA::STATUS
lda (acia),y
and #$10
bne @L4
bit tmp1 ; Keep trying if must try hard
bmi @L0
; Switch back the bank and return
@L3: lda ExecReg
sta IndReg
rts
; Send byte and try again
@L4: ldx SendHead
lda SendBuf,x
ldy #ACIA::DATA
sta (acia),y
inc SendHead
inc SendFreeCnt
jmp @L0
.endproc
;----------------------------------------------------------------------------
; Initialize buffers
InitBuffers:
ldx #0
stx Stopped
stx RecvHead
stx RecvTail
stx SendHead
stx SendTail
dex ; X = 255
stx RecvFreeCnt
stx SendFreeCnt
rts
;----------------------------------------------------------------------------
; Write to the ACIA changing the indirect segment. Offset is in Y, value in A.
write_cmd:
ldy #ACIA::CMD
write: pha
lda #$0F
sta IndReg
pla
sta (acia),y
lda ExecReg
sta IndReg
rts