mirror of
https://github.com/cc65/cc65.git
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7e65f64c6a
and NMI to make sure the NMI handler is loaded into the low 16K of memory which are active when the control is passed from the ROM NMI stub to the user handler. git-svn-id: svn://svn.cc65.org/cc65/trunk@1086 b7a2c559-68d2-44c3-8de9-860c34a00d81
688 lines
16 KiB
ArmAsm
688 lines
16 KiB
ArmAsm
;
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; SwiftLink/Turbo-232 v0.90 device driver, by Craig Bruce, 14-Apr-1998.
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;
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; This software is Public Domain. It is in Buddy assembler format.
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;
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; This device driver uses the SwiftLink RS-232 Serial Cartridge, available from
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; Creative Micro Designs, Inc, and also supports the extensions of the Turbo232
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; Serial Cartridge. Both devices are based on the 6551 ACIA chip. It also
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; supports the "hacked" SwiftLink with a 1.8432 MHz crystal.
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;
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; The code assumes that the kernal + I/O are in context. On the C128, call
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; it from Bank 15. On the C64, don't flip out the Kernal unless a suitable
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; NMI catcher is put into the RAM under then Kernal. For the SuperCPU, the
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; interrupt handling assumes that the 65816 is in 6502-emulation mode.
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;
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;--------------------------------------------------------------------------
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;
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; Adapted for the use with the cc65 runtime library by
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; Ullrich von Bassewitz (uz@musoftware.de) 02-May-1999.
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;
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; All external functions are C callable, the return value is an error code.
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;
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.importzp ptr1, ptr2, tmp1, tmp2
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.import popa, popax
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.export _rs232_init, _rs232_params, _rs232_done, _rs232_get
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.export _rs232_put, _rs232_pause, _rs232_unpause, _rs232_status
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.include "c128.inc"
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NmiExit = $ff33 ;exit address for nmi
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ACIA = $DE00
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;----------------------------------------------------------------------------
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;
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; Global variables
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;
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.bss
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DropCnt: .res 4 ; Number of bytes lost from rx buffer full
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Initialized: .res 1 ; Flag indicating driver is initialized
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Stopped: .res 1 ; Flow-stopped flag
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RtsOff: .res 1 ;
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Errors: .res 1 ; Number of bytes received in error, low byte
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Turbo232: .res 1 ; Flag indicating turbo-232
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HackedFlag: .res 1 ; Flag indicating hacked-crystal swiftlink
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CpuSpeed: .res 1 ; In MHz
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RecvHead: .res 1 ; Head of receive buffer
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RecvTail: .res 1 ; Tail of receive buffer
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RecvFreeCnt: .res 1 ; Number of bytes in receive buffer
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SendHead: .res 1 ; Head of send buffer
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SendTail: .res 1 ; Tail of send buffer
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SendFreeCnt: .res 1 ; Number of bytes free in send buffer
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BaudCode: .res 1 ; Current baud in effect
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; Send and receive buffers: 256 bytes each
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RecvBuf: .res 256
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SendBuf: .res 256
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.data
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NmiContinue: .byte $4c ; JMP instruction for NMI save -- continue
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NmiSave: .res 2 ; normal NMI handler
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; Switftlink register offsets
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RegData = 0 ; Data register
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RegStatus = 1 ; Status register
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RegCommand = 2 ; Command register
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RegControl = 3 ; Control register
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RegClock = 7 ; Turbo232 external baud-rate generator
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; Error codes. Beware: The codes must match the codes in the C header file
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ErrNotInitialized = $01
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ErrBaudTooFast = $02
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ErrBaudNotAvail = $03
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ErrNoData = $04
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ErrOverflow = $05
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.code
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;----------------------------------------------------------------------------
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;
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; unsigned char __fastcall__ rs232_init (char hacked);
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; /* Initialize the serial port, install the interrupt handler. The parameter
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; * must be true (non zero) for a hacked swiftlink and false (zero) otherwise.
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; */
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;
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_rs232_init:
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bit Initialized ;** shut down if started
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bpl @L1
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pha
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jsr _rs232_done
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pla
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;** set hacked-crystal
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@L1: sta HackedFlag
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;** check for turbo-232
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lda #$00
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sta ACIA+RegControl
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tax
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lda ACIA+RegClock
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beq @L3
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dex
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@L3: stx Turbo232
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;** get C128 cpu speed
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lda $d030
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and #$01
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clc
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adc #1
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sta CpuSpeed
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;** check for super-cpu at 20 MHz
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bit SCPU_Detect
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bmi @L4
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bit $d0b8
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bvs @L4
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lda #20
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sta CpuSpeed
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;** initialize buffers & control
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@L4: lda #0
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sta RecvHead
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sta SendHead
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sta RecvTail
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sta SendTail
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sta Errors
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sta Stopped
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lda #255
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sta RecvFreeCnt
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sta SendFreeCnt
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;** set up nmi's
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lda NMIVec
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ldy NMIVec+1
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sta NmiSave+0
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sty NmiSave+1
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lda #<NmiHandler
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ldy #>NmiHandler
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sta NMIVec
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sty NMIVec+1
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;** set default to 2400-8N1, enable interrupts
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lda ACIA+RegData
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lda ACIA+RegStatus
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lda #$18
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bit HackedFlag
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bpl @L5
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lda #$1a
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@L5: sta ACIA+RegControl
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lda #$01
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sta RtsOff
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ora #$08
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sta ACIA+RegCommand
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lda #$06
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sta BaudCode
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;** return
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lda #$ff
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sta Initialized
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lda #$00
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tax
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rts
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;----------------------------------------------------------------------------
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;
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; unsigned char __fastcall__ rs232_params (unsigned char params, unsigned char parity);
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; /* Set the port parameters. Use a combination of the #defined values above. */
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;
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; Set communication parameters.
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;
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; baud rates stops word | parity
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; --------------------- ----- ----- | ---------
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; $00=50 $08=9600 $00=1 $00=8 | $00=none
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; $01=110 $09=19200 $80=2 $20=7 | $20=odd
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; $02=134.5 $0a=38400 $40=6 | $60=even
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; $03=300 $0b=57600 $60=5 | $A0=mark
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; $04=600 $0c=115200 | $E0=space
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; $05=1200 $0d=230400
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; $06=2400 $0e=future
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; $07=4800 $0f=future
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;
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_rs232_params:
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jsr CheckInitialized ;** check initialized
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bcc @L1
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rts
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; Save new parity
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@L1: and #%11100000
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ora #%00000001
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sta tmp2
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; Check cpu speed against baud rate
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jsr popa
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sta tmp1
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and #$0f
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cmp #$0c
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bcc @L3
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ldx CpuSpeed
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cpx #1+1
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bcc @L2
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cmp #$0c
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beq @L3
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cpx #4
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bcs @L3
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@L2: lda #ErrBaudTooFast
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bne @L9
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; Set baud/parameters
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@L3: lda tmp1
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and #$0f
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tax
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lda NormBauds,x
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bit HackedFlag
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bpl @L4
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lda HackBauds,x
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@L4: cmp #$ff
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bne @L5
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lda #ErrBaudNotAvail
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bne @L9
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@L5: tax
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and #$30
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beq @L6
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bit Turbo232
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bmi @L6
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lda #ErrBaudNotAvail
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bne @L9
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@L6: lda tmp1
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and #$0f
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sta BaudCode
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lda tmp1
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and #%11100000
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ora #%00010000
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sta tmp1
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txa
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and #$0f
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ora tmp1
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sta ACIA+RegControl
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txa
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and #%00110000
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beq @L7
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lsr
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lsr
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lsr
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lsr
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eor #%00000011
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sta ACIA+RegClock
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; Set new parity
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@L7: lda tmp2
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sta RtsOff
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ora #%00001000
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sta ACIA+RegCommand
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lda #0
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@L9: ldx #0
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rts
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.rodata
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NormBauds:
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.byte $ff,$ff,$ff,$05,$06,$07,$08,$0a,$0c,$0e,$0f,$10,$20,$30,$ff,$ff
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HackBauds:
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.byte $01,$03,$04,$06,$07,$08,$0a,$0c,$0e,$0f,$ff,$ff,$00,$ff,$ff,$ff
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;in: 0 1 2 3 4 5 6 7 8 9 a b c d e f
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;baud50 110 134 3 6 12 24 48 96 19 38 57 115 230 exp exp
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;out masks: $0F=Baud, val$FF=err
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; $30=t232ExtBaud: $00=none, $10=57.6, $20=115.2, $30=230.4
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.code
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;----------------------------------------------------------------------------
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;
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; unsigned char __fastcall__ rs232_done (void);
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; /* Close the port, deinstall the interrupt hander. You MUST call this function
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; * before terminating the program, otherwise the machine may crash later. If
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; * in doubt, install an exit handler using atexit(). The function will do
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; * nothing, if it was already called.
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; */
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;
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_rs232_done:
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bit Initialized ;** check initialized
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bpl @L9
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; Stop interrupts, drop DTR
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lda RtsOff
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and #%11100010
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ora #%00000010
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sta ACIA+RegCommand
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; Restore NMI vector
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lda NmiSave+0
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ldy NmiSave+1
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sta NMIVec
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sty NMIVec+1
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; Flag uninitialized
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@L9: lda #$00
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sta Initialized
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tax
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rts
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;----------------------------------------------------------------------------
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;
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; unsigned char __fastcall__ rs232_get (char* B);
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; /* Get a character from the serial port. If no characters are available, the
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; * function will return RS_ERR_NO_DATA, so this is not a fatal error.
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; */
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;
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_rs232_get:
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jsr CheckInitialized ; Check if initialized
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bcc @L1
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rts
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; Check for bytes to send
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@L1: sta ptr1
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stx ptr1+1 ; Store pointer to received char
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ldx SendFreeCnt
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cpx #$ff
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beq @L2
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lda #$00
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jsr TryToSend
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; Check for buffer empty
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@L2: lda RecvFreeCnt
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cmp #$ff
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bne @L3
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lda #ErrNoData
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ldx #0
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rts
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; Check for flow stopped & enough free: release flow control
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@L3: ldx Stopped
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beq @L4
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cmp #63
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bcc @L4
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lda #$00
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sta Stopped
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lda RtsOff
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ora #%00001000
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sta ACIA+RegCommand
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; Get byte from buffer
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@L4: ldx RecvHead
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lda RecvBuf,x
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inc RecvHead
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inc RecvFreeCnt
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ldx #$00
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sta (ptr1,x)
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txa ; Return code = 0
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rts
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;----------------------------------------------------------------------------
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;
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; unsigned char __fastcall__ rs232_put (char B);
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; /* Send a character via the serial port. There is a transmit buffer, but
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; * transmitting is not done via interrupt. The function returns
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; * RS_ERR_OVERFLOW if there is no space left in the transmit buffer.
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; */
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;
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_rs232_put:
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jsr CheckInitialized ; Check initialized
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bcc @L1
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rts
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; Try to send
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@L1: ldx SendFreeCnt
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cpx #$ff
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beq @L2
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pha
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lda #$00
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jsr TryToSend
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pla
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; Put byte into send buffer & send
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@L2: ldx SendFreeCnt
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bne @L3
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lda #ErrOverflow
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ldx #$00
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rts
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@L3: ldx SendTail
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sta SendBuf,x
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inc SendTail
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dec SendFreeCnt
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lda #$ff
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jsr TryToSend
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lda #$00
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tax
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rts
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;----------------------------------------------------------------------------
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;
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; unsigned char __fastcall__ rs232_pause (void);
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; /* Assert flow control and disable interrupts. */
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;
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_rs232_pause:
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; Check initialized
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jsr CheckInitialized
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bcc @L1
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rts
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; Assert flow control
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@L1: lda RtsOff
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sta Stopped
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sta ACIA+RegCommand
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; Delay for flow stop to be received
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ldx BaudCode
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lda PauseTimes,x
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jsr DelayMs
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; Stop rx interrupts
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lda RtsOff
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ora #$02
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sta ACIA+RegCommand
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lda #0
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tax
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rts
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.rodata
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; Delay times: 32 byte-receive times in milliseconds, or 100 max.
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; Formula = 320,000 / baud
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PauseTimes:
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.byte 100,100,100,100,100,100,100,067,034,017,009,006,003,002,001,001
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;in: 0 1 2 3 4 5 6 7 8 9 a b c d e f
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;baud50 110 134 3 6 12 24 48 96 19 38 57 115 230 exp exp
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.code
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;----------------------------------------------------------------------------
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;
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; unsigned char __fastcall__ rs232_unpause (void);
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; /* Re-enable interrupts and release flow control */
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;
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_rs232_unpause:
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; Check initialized
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jsr CheckInitialized
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bcc @L1
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rts
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; Re-enable rx interrupts & release flow control
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@L1: lda #$00
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sta Stopped
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lda RtsOff
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ora #%00001000
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sta ACIA+RegCommand
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; Poll for stalled char & exit
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jsr PollReceive
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lda #0
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tax
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rts
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;----------------------------------------------------------------------------
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;
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; unsigned char __fastcall__ rs232_status (unsigned char* status,
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; unsigned char* errors);
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; /* Return the serial port status. */
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;
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_rs232_status:
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sta ptr2
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stx ptr2+1
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jsr popax
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sta ptr1
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stx ptr1+1
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jsr CheckInitialized
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bcs @L9
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; Get status
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lda ACIA+RegStatus
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ldy #0
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sta (ptr1),y
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jsr PollReceive ; bug-recovery hack
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lda Errors
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sta (ptr2),y
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tya
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tax
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@L9: rts
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;----------------------------------------------------------------------------
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;
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; NMI handler
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; C128 NMI overhead=76 cycles: int=7, maxLatency=6, ROMenter=33, ROMexit=30
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; C64 NMI overhead=76 cycles: int=7, maxLatency=6, ROMenter=34, ROMexit=29
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;
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; timing: normal=76+43+9=128 cycles, assertFlow=76+52+9=137 cycles
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;
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; C128 @ 115.2k: 177 cycles avail (fast)
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; C64 @ 57.6k: 177 cycles avail, worstAvail=177-43? = 134
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; SCPU @ 230.4k: 868 cycles avail: for a joke!
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;
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; Because of the C128 banking, the NMI handler must go into the non banked
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; memory, since the ROM NMI entry point will switch to a configuration where
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; only the lowest 16K of RAM are visible. We will place the NMI handler into
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; it's own segment and map this segment into the lower 16K in the linker
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; config.
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.segment "NMI"
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NmiHandler:
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lda #CC65_MMU_CFG ;(2)
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sta MMU_CR ;(4)
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lda ACIA+RegStatus ;(4) ;status ;check for byte received
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and #$08 ;(2)
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beq @L9 ;(2*)
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lda ACIA+RegStatus ;(4) opt ;status ;check for receive errors
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and #$07 ;(2) opt
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beq @L1 ;(3*)opt
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inc Errors ;(5^)opt
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@L1: lda ACIA+RegData ;(4) ;data ;get byte and put into receive buffer
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ldy RecvTail ;(4)
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ldx RecvFreeCnt ;(4)
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beq @L3 ;(2*)
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sta RecvBuf,y ;(5)
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inc RecvTail ;(6)
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dec RecvFreeCnt ;(6)
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cpx #33 ;(2) ;check for buffer space low
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bcc @L2 ;(2*)
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jmp NmiExit ;(3)
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; Assert flow control
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@L2: lda RtsOff ;(3) ;assert flow control if buffer space too low
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sta ACIA+RegCommand ;(4) ;command
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sta Stopped ;(3)
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jmp NmiExit ;(3)
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; Drop this char
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@L3: inc DropCnt+0 ;not time-critical
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bne @L4
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inc DropCnt+1
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bne @L4
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inc DropCnt+2
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bne @L4
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inc DropCnt+3
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@L4: jmp NmiExit
|
|
|
|
@L9: jmp NmiContinue
|
|
|
|
|
|
.code
|
|
|
|
;----------------------------------------------------------------------------
|
|
;
|
|
; CheckInitialized - internal check if initialized
|
|
; Set carry and an error code if not initialized, clear carry and do not
|
|
; change any registers if initialized.
|
|
;
|
|
|
|
CheckInitialized:
|
|
bit Initialized
|
|
bmi @L1
|
|
lda #ErrNotInitialized
|
|
ldx #0
|
|
sec
|
|
rts
|
|
|
|
@L1: clc
|
|
rts
|
|
|
|
;----------------------------------------------------------------------------
|
|
; Try to send a byte. Internal routine. A = TryHard
|
|
|
|
TryToSend:
|
|
sta tmp1 ; Remember tryHard flag
|
|
@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: lda ACIA+RegStatus
|
|
and #$10
|
|
bne @L4
|
|
bit tmp1 ;keep trying if must try hard
|
|
bmi @L0
|
|
@L3: rts
|
|
|
|
;** send byte and try again
|
|
|
|
@L4: ldx SendHead
|
|
lda SendBuf,x
|
|
sta ACIA+RegData
|
|
inc SendHead
|
|
inc SendFreeCnt
|
|
jmp @L0
|
|
|
|
;----------------------------------------------------------------------------
|
|
;
|
|
; PollReceive - poll for rx char
|
|
; This function is useful in odd cases where the 6551 has a character in
|
|
; it but it fails to raise an NMI. It might be edge-triggering conditions?
|
|
; Actually, I'm not entirely sure that this condition can still arrise, but
|
|
; calling this function does no harm.
|
|
;
|
|
|
|
PollReceive:
|
|
lda #$08
|
|
and ACIA+RegStatus
|
|
beq @L9
|
|
and ACIA+RegStatus
|
|
beq @L9
|
|
lda ACIA+RegData
|
|
ldx RecvFreeCnt
|
|
beq @L9
|
|
ldx RecvTail
|
|
sta RecvBuf,x
|
|
inc RecvTail
|
|
dec RecvFreeCnt
|
|
@L9: rts
|
|
|
|
;----------------------------------------------------------------------------
|
|
;
|
|
; DelayMs : delay for given number of milliseconds
|
|
; This implementation isn't very rigerous; it merely delays for the
|
|
; approximate number of clock cycles for the processor speed.
|
|
; Algorithm:
|
|
; repeat for number of milliseconds:
|
|
; repeat for number of MHz of cpu speed:
|
|
; delay for 1017 clock cycles
|
|
;
|
|
|
|
DelayMs: ;( .A=milliseconds )
|
|
@L1: ldy CpuSpeed
|
|
@L2: ldx #203 ;(2)
|
|
@L3: dex ;(2)
|
|
bne @L3 ;(3) // 1017 cycles
|
|
dey
|
|
bne @L2
|
|
sec
|
|
sbc #1
|
|
bne @L1
|
|
rts
|
|
|
|
.end
|
|
|
|
|
|
|