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https://github.com/cc65/cc65.git
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663 lines
15 KiB
ArmAsm
663 lines
15 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 "c64.inc"
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.include "rs232.inc"
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NmiExit = $febc ;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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.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/C64 cpu speed
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lda #1
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sta CpuSpeed
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;** check for super-cpu at 20 MHz
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bit $d0bc
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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 #$06
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sta BaudCode
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; Done
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ldx #$ff
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stx Initialized
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inx ; X = 0
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txa ; A = 0
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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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bit Initialized
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bmi @L1
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jmp NotInitialized ; Return an error code
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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 #RS_ERR_BAUD_TOO_FAST
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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 #RS_ERR_BAUD_NOT_AVAIL
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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 #RS_ERR_BAUD_NOT_AVAIL
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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 #$00
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sta Initialized
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tax
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rts
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;----------------------------------------------------------------------------
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;
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; unsigned char __fastcall__ rs232_get (char* B);
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; /* Get a character from the serial port. If no characters are available, the
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; * function will return RS_ERR_NO_DATA, so this is not a fatal error.
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; */
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;
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_rs232_get:
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bit Initialized
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bpl NotInitialized ; Jump if not initialized
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; Check for bytes to send
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sta ptr1
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stx ptr1+1 ; Store pointer to received char
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ldx SendFreeCnt
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cpx #$ff
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beq @L2
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lda #$00
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jsr TryToSend
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; Check for buffer empty
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@L2: lda RecvFreeCnt ; (25)
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cmp #$ff
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bne @L3
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lda #RS_ERR_NO_DATA
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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 ; (34)
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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 ; (41)
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lda RecvBuf,x
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inc RecvHead
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inc RecvFreeCnt
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ldx #$00 ; (59)
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sta (ptr1,x)
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txa ; Return code = 0
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rts
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;----------------------------------------------------------------------------
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;
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; RS232 module not initialized
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NotInitialized:
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lda #<RS_ERR_NOT_INITIALIZED
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ldx #>RS_ERR_NOT_INITIALIZED
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rts
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;----------------------------------------------------------------------------
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;
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; unsigned char __fastcall__ rs232_put (char B);
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; /* Send a character via the serial port. There is a transmit buffer, but
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; * transmitting is not done via interrupt. The function returns
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; * RS_ERR_OVERFLOW if there is no space left in the transmit buffer.
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; */
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;
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_rs232_put:
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bit Initialized
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bpl NotInitialized ; Jump if not initialized
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; Try to send
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ldx SendFreeCnt
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cpx #$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 #RS_ERR_OVERFLOW
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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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bit Initialized
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bpl NotInitialized ; Jump if not initialized
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; Assert flow control
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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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bit Initialized
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bpl NotInitialized ; Jump if not initialized
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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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bit Initialized
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bmi @L1
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jmp NotInitialized
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; Get status
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@L1: 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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NmiHandler:
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pha
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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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cld
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txa
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pha
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tya
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pha
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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
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@L9: pla
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jmp NmiContinue
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;----------------------------------------------------------------------------
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; Try to send a byte. Internal routine. A = TryHard
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TryToSend:
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sta tmp1 ; Remember tryHard flag
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@L0: lda SendFreeCnt
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cmp #$ff
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beq @L3 ; Bail out
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; Check for flow stopped
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@L1: lda Stopped
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bne @L3 ; Bail out
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;** 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
|
|
|
|
|
|
|