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;----------------------------------------------------------------------------------------------
; SilverSurfer polling mode driver (w) 2001 Groepaz/Hitmen
; - this one is optimized for size and reliability (rather than maximum speed or efficiency)
;----------------------------------------------------------------------------------------------
; ss_detect detect silversurfer, returns CARRY=1 on error
; ss_init init uart, call with baudrate divisor lowbyte in A
; ss_getchr get byte (blocking) - returns next byte in A
; ss_getchr2 get byte (non blocking, returns byte in A or CARRY=1 - error)
; ss_putchr sends byte in A
;----------------------------------------------------------------------------------------------
; all functions except ss_detect and ss_init use/modify AKKU only.
;----------------------------------------------------------------------------------------------
;.include "silversurfer.inc" ; fifo defines
.export ss_detect,ss_init
.export ss_getchr,ss_getchr2,ss_putchr
.export ss_stat_reciever_ready
.export ss_stat_data_available
.export ss_stat_transmit_ready
.export ss_pause,ss_unpause
;----------------------------------------------------------------------------------------------
; detect silversurfer, returns CARRY=1 on error
;----------------------------------------------------------------------------------------------
ss_detect:
;
; enable ssurfer-port
;
lda $de01
ora #$01
sta $de01
;
; check if scratch-register available
;
ldx #$00
@l1:
stx fifo_scratch
cpx fifo_scratch
bne @sk1
inx
bne @l1
; ok
clc
rts
@sk1:
; error
sec
rts
;----------------------------------------------------------------------------------------------
; init uart, call with baudrate divisor lowbyte in A
;----------------------------------------------------------------------------------------------
;
; 9600 $30
; 19200 $18
; 38400 $0c
; 57600 $08
; 115000 $04
;
;----------------------------------------------------------------------------------------------
ss_init:
tax
;
; enable ssurfer-port
;
lda $de01
ora #$01
sta $de01
;
; init and set baudrate
;
lda #%10000111
sta fifo_fcr
; that delay thing really needed ?!
; (original datasheet mentions a delay here)
; ldy #$00
; dey
; bny *-1
; set dlab
lda #%10000011
sta fifo_lcr
; set baudrate
stx fifo_dll
lda #$00
sta fifo_dlm
; reset dlab
lda #%00000011
sta fifo_lcr
; disable nmi's from ssurfer
lda #%00000000
sta fifo_ier
; activate dtr
jmp ss_pause
;----------------------------------------------------------------------------------------------
; check if data available
; no data: AKKU=0
; data: AKKU!=0
;----------------------------------------------------------------------------------------------
ss_stat_data_available:
lda fifo_lsr
and #%00000001
rts
;----------------------------------------------------------------------------------------------
; check if transmit register empty
; busy: AKKU=0
; empty: AKKU!=0
;----------------------------------------------------------------------------------------------
ss_stat_transmit_ready:
lda fifo_lsr
and #%00100000
rts
;----------------------------------------------------------------------------------------------
; check if reciever ready
; busy: AKKU=0
; ready: AKKU!=0
;----------------------------------------------------------------------------------------------
ss_stat_reciever_ready:
; check cts
lda fifo_msr
and #%00010000
rts
;----------------------------------------------------------------------------------------------
; Flow-Control
;----------------------------------------------------------------------------------------------
ss_unpause:
; activate rts
lda #%00000011
sta fifo_mcr
rts
ss_pause:
; deactivate rts
lda #%00000001
sta fifo_mcr
rts
;----------------------------------------------------------------------------------------------
; get byte (non blocking, returns byte in A or CARRY=1 - error)
;----------------------------------------------------------------------------------------------
ss_getchr2:
; check if byte available
jsr ss_stat_data_available
bne sk32 ; yes
; release flow-control
jsr ss_unpause
sk32:
; set flow-control
jsr ss_pause
; check if byte available
jsr ss_stat_data_available
bne sk33 ; yes
sec
rts
sk33:
; get byte
lda fifo_rxd
clc
rts
;----------------------------------------------------------------------------------------------
; get byte (blocking) - returns next byte in A
;----------------------------------------------------------------------------------------------
ss_getchr:
@lp1:
jsr ss_getchr2
bcs @lp1 ; no byte read
rts
;----------------------------------------------------------------------------------------------
; send byte in A (blocking) - waits until byte can be send
;----------------------------------------------------------------------------------------------
ss_putchr:
pha
; wait until reciever is ready to recieve
l2:
jsr ss_stat_reciever_ready
beq l2
; wait until send buffer is empty
l1:
jsr ss_stat_transmit_ready
beq l1
; send byte
pla
sta fifo_txd
rts
;----------------------------------------------------------------------------------------------
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