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[/] [thor/] [trunk/] [software/] [boot_tb/] [Serial.asm] - Blame information for rev 30

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UART            EQU     0xC0A00
UART_TX         EQU     0xC0A00
UART_RX         EQU     0xC0A00
UART_LS         EQU     0xC0A01
UART_MS         EQU     0xC0A02
UART_IS         EQU     0xC0A03
UART_IE         EQU     0xC0A04
UART_FF         EQU     0xC0A05
UART_MC         EQU     0xC0A06
UART_CTRL       EQU     0xC0A07
UART_CM0        EQU     0xC0A08
UART_CM1        EQU     0xC0A09
UART_CM2        EQU     0xC0A0A
UART_CM3        EQU     0xC0A0B
UART_SPR        EQU     0xC0A0F
 
;------------------------------------------------------------------------------
;------------------------------------------------------------------------------
 
;==============================================================================
; Serial port
;==============================================================================
        code
;------------------------------------------------------------------------------
; Initialize UART
;------------------------------------------------------------------------------
 
                align   8
ser_jmp:
                jmp             SerialIRQ[c0]
 
SerialInit:
                addui   sp,sp,#-8
                sws             c1,[sp]
                ldis    hs,#$FFD00000
                ldis    hs.lmt,#$100000
;               ldi             r1,#$0218DEF4   ; constant for clock multiplier with 18.75MHz clock for 9600 baud
;               ldi             r1,#$03254E6E   ; constant for clock multiplier with 12.5MHz clock for 9600 baud
                ldi             r1,#$00C9539B   ; constant for clock multiplier with 50.0MHz clock for 9600 baud
                shrui   r1,r1,#8          ; drop the LSB (not used)
                sb      r1,hs:UART_CM1
                shrui   r1,r1,#8
                sb      r1,hs:UART_CM2
                shrui   r1,r1,#8
                sb      r1,hs:UART_CM3
                sb      r0,hs:UART_CTRL     ; no hardware flow control
                sc              r0,Uart_rxhead          ; reset buffer indexes
                sc              r0,Uart_rxtail
                ldi             r1,#0x1f0
                sc              r1,Uart_foff            ; set threshold for XOFF
                ldi             r1,#0x010
                sc              r1,Uart_fon                     ; set threshold for XON
                ldi             r1,#1
                sb              r1,hs:UART_IE           ; enable receive interrupt only
                sb              r0,Uart_rxrts           ; no RTS/CTS signals available
                sb              r0,Uart_txrts           ; no RTS/CTS signals available
                sb              r0,Uart_txdtr           ; no DTR signals available
                sb              r0,Uart_rxdtr           ; no DTR signals available
                ldi             r1,#1
                sb              r1,Uart_txxon           ; for now
                ldi             r1,#1
;               sb              r1,SERIAL_SEMA
                ; setup IRQ vector
                lla             r1,cs:ser_jmp
                ldi             r2,#199
                bsr             set_vector
                lws             c1,[sp]
                addui   sp,sp,#8
                rts
 
;---------------------------------------------------------------------------------
; Get character directly from serial port. Blocks until a character is available.
;---------------------------------------------------------------------------------
;
SerialGetCharDirect:
sgc1:
                lvb             r1,hs:UART_LS   ; uart status
                biti    p0,r1,#1                ; is there a char available ?
p0.eq   br              sgc1
                lvb             r1,hs:UART_RX
                rts
 
;------------------------------------------------
; Check for a character at the serial port
; returns r1 = 1 if char available, 0 otherwise
;------------------------------------------------
;
SerialCheckForCharDirect:
                lvb             r1,hs:UART_LS                   ; uart status
                andi    r1,r1,#rxfull                   ; is there a char available ?
                rts
 
;-----------------------------------------
; Put character to serial port
; r1 = char to put
;-----------------------------------------
;
SerialPutChar:
                addui   sp,sp,#-48
                sw              r2,[sp]
                sw              r3,8[sp]
                sw              r4,16[sp]
                sw              r5,24[sp]
                sws             p0,32[sp]
                sws             lc,40[sp]
                lvb             r2,hs:UART_MC
                ori             r2,r2,#3                ; assert DTR / RTS
                sb              r2,hs:UART_MC
                lb              r2,Uart_txrts
                tst             p0,r2
p0.eq   br              spcb1
                lw              r4,Milliseconds
                ldis    lc,#999                 ; delay count (1 s)
spcb3:
                lvb             r2,hs:UART_MS
                biti    p0,r2,#$10              ; is CTS asserted ?
p0.ne   br              spcb1
                lw              r5,Milliseconds
                cmp             p0,r4,r5
p0.eq   br              spcb3
                mov             r4,r5
                loop    spcb3
                br              spcabort
spcb1:
                lb              r2,Uart_txdtr
                tst             p0,r2
p0.eq   br              spcb2
                lw              r4,Milliseconds
                ldis    lc,#999         ; delay count
spcb4:
                lvb             r2,hs:UART_MS
                biti    p0,r2,#$20              ; is DSR asserted ?
p0.ne   br              spcb2
                lw              r5,Milliseconds
                cmp             p0,r4,r5
p0.eq   br              spcb4
                mov             r4,r5
                loop    spcb4
                br              spcabort
spcb2:
                lb              r2,Uart_txxon
                tst             p0,r2
p0.eq   br              spcb5
spcb6:
                lb              r2,Uart_txxonoff
                tst             p0,r2
p0.eq   br              spcb5
                lvb             r4,hs:UART_MS
                biti    p0,r4,#0x80             ; DCD ?
p0.ne   br              spcb6
spcb5:
                lw              r4,Milliseconds
                ldis    lc,#999         ; wait up to 1s
spcb8:
                lvb             r2,hs:UART_LS
                biti    p0,r2,#0x20                     ; tx not full ?
p0.ne   br              spcb7
                lw              r5,Milliseconds
                cmp             p0,r4,r5
p0.eq   br              spcb8
                mov             r4,r5
                loop    spcb8
                br              spcabort
spcb7:
                sb              r1,hs:UART_TX
spcabort:
                lw              r2,[sp]
                lw              r3,8[sp]
                lw              r4,16[sp]
                lw              r5,24[sp]
                lws             p0,32[sp]
                lws             lc,40[sp]
                addui   sp,sp,#40
                rts
 
;-------------------------------------------------
; Compute number of characters in recieve buffer.
; r4 = number of chars
;-------------------------------------------------
CharsInRxBuf:
                lcu             r4,Uart_rxhead
                lcu             r3,Uart_rxtail
                subu    r4,r4,r3
                tst             p0,r4
p0.gt   br              cirxb1
                ldi             r4,#0x200
                addu    r4,r4,r3
                lcu             r3,Uart_rxhead
                subu    r4,r4,r3
cirxb1:
                rts
 
;----------------------------------------------
; Get character from rx fifo
; If the fifo is empty enough then send an XON
;----------------------------------------------
;
SerialGetChar:
                addui   sp,sp,#-40
                sw              r2,[sp]
                sw              r3,8[sp]
                sw              r4,16[sp]
                sw              r5,24[sp]
                sws             c1,32[sp]
                lcu             r3,Uart_rxhead
                lcu             r2,Uart_rxtail
                cmp             p0,r2,r3
p0.eq   br              sgcfifo1                ; is there a char available ?
                lbu             r1,Uart_rxfifo[r2]      ; get the char from the fifo into r1
                addui   r2,r2,#1                ; increment the fifo pointer
                andi    r2,r2,#$1ff
                sc              r2,Uart_rxtail
                lb              r2,Uart_rxflow          ; using flow control ?
                tst             p0,r2
p0.eq   br              sgcfifo2
                lcu             r3,Uart_fon             ; enough space in Rx buffer ?
                bsr             CharsInRxBuf
                cmp             p0,r4,r3
p0.gt   br              sgcfifo2
                sb              r0,Uart_rxflow          ; flow off
                lb              r4,Uart_rxrts
                tst             p0,r4
p0.eq   br              sgcfifo3
                lb              r4,hs:UART_MC           ; set rts bit in MC
                ori             r4,r4,#2
                sb              r4,hs:UART_MC
sgcfifo3:
                lb              r4,Uart_rxdtr
                tst             p0,r4
p0.eq   br              sgcfifo4
                lb              r4,hs:UART_MC           ; set DTR
                ori             r4,r4,#1
                sb              r4,hs:UART_MC
sgcfifo4:
                lb              r4,Uart_rxxon
                tst             p0,r4
p0.eq   br              sgcfifo5
                ldi             r4,#XON
                sb              r4,hs:UART
sgcfifo5:
sgcfifo2:                                       ; return with char in r1
                lw              r2,[sp]
                lw              r3,8[sp]
                lw              r4,16[sp]
                lw              r5,24[sp]
                lws             c1,32[sp]
                addui   sp,sp,#40
                rts
sgcfifo1:
                ldi             r1,#-1                          ; no char available
                lw              r2,[sp]
                lw              r3,8[sp]
                lw              r4,16[sp]
                lw              r5,24[sp]
                lws             c1,32[sp]
                addui   sp,sp,#40
                rts
 
 
;-----------------------------------------
; Serial port IRQ
;-----------------------------------------
;
SerialIRQ:
                sync
                addui   r31,r31,#-64
                sw              r1,[r31]
                sw              r2,8[r31]
                sw              r4,16[r31]
                sws             p0,24[r31]
                sw              r3,32[r31]
                sws             c1,40[r31]
                sws             hs,48[r31]
                sws             hs.lmt,56[r31]
                ldis    hs,#$FFD00000
                ldis    hs.lmt,#$100000
 
                lb      r1,hs:UART_IS  ; get interrupt status
                tst             p0,r1
p0.gt   br              sirq1                   ; no interrupt
                andi    r1,r1,#0x7f     ; switch on interrupt type
                biti    p0,r1,#4
p0.ne   br              srxirq
                biti    p0,r1,#$0C
p0.ne   br              stxirq
                biti    p0,r1,#$10
p0.ne   br              smsirq
                ; unknown IRQ type
sirq1:
                lw              r1,[r31]
                lw              r2,8[r31]
                lw              r4,16[r31]
                lws             p0,24[r31]
                lw              r3,32[r31]
                lws             c1,40[r31]
                lws             hs,48[r31]
                lws             hs.lmt,56[r31]
                addui   r31,r31,#64
                sync
                rti
 
; Get the modem status and record it
smsirq:
                lbu     r1,hs:UART_MS
                sb      r1,Uart_ms
                br              sirq1
 
stxirq:
                br              sirq1
 
; Get a character from the uart and store it in the rx fifo
srxirq:
srxirq1:
                lbu     r1,hs:UART_RX      ; get the char (clears interrupt)
                lbu     r3,Uart_txxon
                tst             p0,r3
p0.eq   br              srxirq3
                cmpi    p0,r1,#XOFF
p0.ne   br              srxirq2
                ldi     r1,#1
                sb              r1,Uart_txxonoff
                br              srxirq5
srxirq2:
                cmpi    p0,r1,#XON
p0.ne   br              srxirq3
                sb              r0,Uart_txxonoff
                br              srxirq5
srxirq3:
                sb              r0,Uart_txxonoff
                lcu             r4,Uart_rxhead
                sb              r1,Uart_rxfifo[r4]  ; store in buffer
                addui   r4,r4,#1
                andi    r4,r4,#$1ff
                sc              r4,Uart_rxhead
srxirq5:
                lb      r1,hs:UART_LS   ; check for another ready character
                biti    p0,r1,#1        ; check rxfull bit
p0.ne   br              srxirq1                 ; loop back for another character
                lb              r1,Uart_rxflow          ; are we using flow controls?
                tst             p0,r1
p0.ne   br              srxirq8
                bsr             CharsInRxBuf
                lb              r1,Uart_foff
                cmp             p0,r4,r1
p0.lt   br              srxirq8
                ldi             r1,#1
                sb              r1,Uart_rxflow
                lb              r1,Uart_rxrts
                tst             p0,r1
p0.eq   br              srxirq6
                lb              r1,hs:UART_MC
                andi    r1,r1,#$FD              ; turn off RTS
                sb              r1,hs:UART_MC
srxirq6:
                lb              r1,Uart_rxdtr
                tst             p0,r1
 
 p0.eq  br              srxirq7
                lb              r1,hs:UART_MC
                andi    r1,r1,#$FE              ; turn off DTR
                sb              r1,hs:UART_MC
srxirq7:
                lb              r1,Uart_rxxon
                tst             p0,r1
p0.eq   br              srxirq8
                ldi             r1,#XOFF
                sb              r1,hs:UART_TX
srxirq8:
                br              sirq1
 

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[/] [thor/] [trunk/] [software/] [boot_tb/] [Serial.asm] - Blame information for rev 30

Line No.	Rev	Author	Line
1	28	robfinch	`UART EQU 0xC0A00`
2			`UART_TX EQU 0xC0A00`
3			`UART_RX EQU 0xC0A00`
4			`UART_LS EQU 0xC0A01`
5			`UART_MS EQU 0xC0A02`
6			`UART_IS EQU 0xC0A03`
7			`UART_IE EQU 0xC0A04`
8			`UART_FF EQU 0xC0A05`
9			`UART_MC EQU 0xC0A06`
10			`UART_CTRL EQU 0xC0A07`
11			`UART_CM0 EQU 0xC0A08`
12			`UART_CM1 EQU 0xC0A09`
13			`UART_CM2 EQU 0xC0A0A`
14			`UART_CM3 EQU 0xC0A0B`
15			`UART_SPR EQU 0xC0A0F`
16
17			`;------------------------------------------------------------------------------`
18			`;------------------------------------------------------------------------------`
19
20			`;==============================================================================`
21			`; Serial port`
22			`;==============================================================================`
23			`code`
24			`;------------------------------------------------------------------------------`
25			`; Initialize UART`
26			`;------------------------------------------------------------------------------`
27
28			`align 8`
29			`ser_jmp:`
30			`jmp SerialIRQ[c0]`
31
32			`SerialInit:`
33			`addui sp,sp,#-8`
34			`sws c1,[sp]`
35			`ldis hs,#$FFD00000`
36			`ldis hs.lmt,#$100000`
37			`; ldi r1,#$0218DEF4 ; constant for clock multiplier with 18.75MHz clock for 9600 baud`
38			`; ldi r1,#$03254E6E ; constant for clock multiplier with 12.5MHz clock for 9600 baud`
39			`ldi r1,#$00C9539B ; constant for clock multiplier with 50.0MHz clock for 9600 baud`
40			`shrui r1,r1,#8 ; drop the LSB (not used)`
41			`sb r1,hs:UART_CM1`
42			`shrui r1,r1,#8`
43			`sb r1,hs:UART_CM2`
44			`shrui r1,r1,#8`
45			`sb r1,hs:UART_CM3`
46			`sb r0,hs:UART_CTRL ; no hardware flow control`
47			`sc r0,Uart_rxhead ; reset buffer indexes`
48			`sc r0,Uart_rxtail`
49			`ldi r1,#0x1f0`
50			`sc r1,Uart_foff ; set threshold for XOFF`
51			`ldi r1,#0x010`
52			`sc r1,Uart_fon ; set threshold for XON`
53			`ldi r1,#1`
54			`sb r1,hs:UART_IE ; enable receive interrupt only`
55			`sb r0,Uart_rxrts ; no RTS/CTS signals available`
56			`sb r0,Uart_txrts ; no RTS/CTS signals available`
57			`sb r0,Uart_txdtr ; no DTR signals available`
58			`sb r0,Uart_rxdtr ; no DTR signals available`
59			`ldi r1,#1`
60			`sb r1,Uart_txxon ; for now`
61			`ldi r1,#1`
62			`; sb r1,SERIAL_SEMA`
63			`; setup IRQ vector`
64			`lla r1,cs:ser_jmp`
65			`ldi r2,#199`
66			`bsr set_vector`
67			`lws c1,[sp]`
68			`addui sp,sp,#8`
69			`rts`
70
71			`;---------------------------------------------------------------------------------`
72			`; Get character directly from serial port. Blocks until a character is available.`
73			`;---------------------------------------------------------------------------------`
74			`;`
75			`SerialGetCharDirect:`
76			`sgc1:`
77			`lvb r1,hs:UART_LS ; uart status`
78			`biti p0,r1,#1 ; is there a char available ?`
79			`p0.eq br sgc1`
80			`lvb r1,hs:UART_RX`
81			`rts`
82
83			`;------------------------------------------------`
84			`; Check for a character at the serial port`
85			`; returns r1 = 1 if char available, 0 otherwise`
86			`;------------------------------------------------`
87			`;`
88			`SerialCheckForCharDirect:`
89			`lvb r1,hs:UART_LS ; uart status`
90			`andi r1,r1,#rxfull ; is there a char available ?`
91			`rts`
92
93			`;-----------------------------------------`
94			`; Put character to serial port`
95			`; r1 = char to put`
96			`;-----------------------------------------`
97			`;`
98			`SerialPutChar:`
99			`addui sp,sp,#-48`
100			`sw r2,[sp]`
101			`sw r3,8[sp]`
102			`sw r4,16[sp]`
103			`sw r5,24[sp]`
104			`sws p0,32[sp]`
105			`sws lc,40[sp]`
106			`lvb r2,hs:UART_MC`
107			`ori r2,r2,#3 ; assert DTR / RTS`
108			`sb r2,hs:UART_MC`
109			`lb r2,Uart_txrts`
110			`tst p0,r2`
111			`p0.eq br spcb1`
112			`lw r4,Milliseconds`
113			`ldis lc,#999 ; delay count (1 s)`
114			`spcb3:`
115			`lvb r2,hs:UART_MS`
116			`biti p0,r2,#$10 ; is CTS asserted ?`
117			`p0.ne br spcb1`
118			`lw r5,Milliseconds`
119			`cmp p0,r4,r5`
120			`p0.eq br spcb3`
121			`mov r4,r5`
122			`loop spcb3`
123			`br spcabort`
124			`spcb1:`
125			`lb r2,Uart_txdtr`
126			`tst p0,r2`
127			`p0.eq br spcb2`
128			`lw r4,Milliseconds`
129			`ldis lc,#999 ; delay count`
130			`spcb4:`
131			`lvb r2,hs:UART_MS`
132			`biti p0,r2,#$20 ; is DSR asserted ?`
133			`p0.ne br spcb2`
134			`lw r5,Milliseconds`
135			`cmp p0,r4,r5`
136			`p0.eq br spcb4`
137			`mov r4,r5`
138			`loop spcb4`
139			`br spcabort`
140			`spcb2:`
141			`lb r2,Uart_txxon`
142			`tst p0,r2`
143			`p0.eq br spcb5`
144			`spcb6:`
145			`lb r2,Uart_txxonoff`
146			`tst p0,r2`
147			`p0.eq br spcb5`
148			`lvb r4,hs:UART_MS`
149			`biti p0,r4,#0x80 ; DCD ?`
150			`p0.ne br spcb6`
151			`spcb5:`
152			`lw r4,Milliseconds`
153			`ldis lc,#999 ; wait up to 1s`
154			`spcb8:`
155			`lvb r2,hs:UART_LS`
156			`biti p0,r2,#0x20 ; tx not full ?`
157			`p0.ne br spcb7`
158			`lw r5,Milliseconds`
159			`cmp p0,r4,r5`
160			`p0.eq br spcb8`
161			`mov r4,r5`
162			`loop spcb8`
163			`br spcabort`
164			`spcb7:`
165			`sb r1,hs:UART_TX`
166			`spcabort:`
167			`lw r2,[sp]`
168			`lw r3,8[sp]`
169			`lw r4,16[sp]`
170			`lw r5,24[sp]`
171			`lws p0,32[sp]`
172			`lws lc,40[sp]`
173			`addui sp,sp,#40`
174			`rts`
175
176			`;-------------------------------------------------`
177			`; Compute number of characters in recieve buffer.`
178			`; r4 = number of chars`
179			`;-------------------------------------------------`
180			`CharsInRxBuf:`
181			`lcu r4,Uart_rxhead`
182			`lcu r3,Uart_rxtail`
183			`subu r4,r4,r3`
184			`tst p0,r4`
185			`p0.gt br cirxb1`
186			`ldi r4,#0x200`
187			`addu r4,r4,r3`
188			`lcu r3,Uart_rxhead`
189			`subu r4,r4,r3`
190			`cirxb1:`
191			`rts`
192
193			`;----------------------------------------------`
194			`; Get character from rx fifo`
195			`; If the fifo is empty enough then send an XON`
196			`;----------------------------------------------`
197			`;`
198			`SerialGetChar:`
199			`addui sp,sp,#-40`
200			`sw r2,[sp]`
201			`sw r3,8[sp]`
202			`sw r4,16[sp]`
203			`sw r5,24[sp]`
204			`sws c1,32[sp]`
205			`lcu r3,Uart_rxhead`
206			`lcu r2,Uart_rxtail`
207			`cmp p0,r2,r3`
208			`p0.eq br sgcfifo1 ; is there a char available ?`
209			`lbu r1,Uart_rxfifo[r2] ; get the char from the fifo into r1`
210			`addui r2,r2,#1 ; increment the fifo pointer`
211			`andi r2,r2,#$1ff`
212			`sc r2,Uart_rxtail`
213			`lb r2,Uart_rxflow ; using flow control ?`
214			`tst p0,r2`
215			`p0.eq br sgcfifo2`
216			`lcu r3,Uart_fon ; enough space in Rx buffer ?`
217			`bsr CharsInRxBuf`
218			`cmp p0,r4,r3`
219			`p0.gt br sgcfifo2`
220			`sb r0,Uart_rxflow ; flow off`
221			`lb r4,Uart_rxrts`
222			`tst p0,r4`
223			`p0.eq br sgcfifo3`
224			`lb r4,hs:UART_MC ; set rts bit in MC`
225			`ori r4,r4,#2`
226			`sb r4,hs:UART_MC`
227			`sgcfifo3:`
228			`lb r4,Uart_rxdtr`
229			`tst p0,r4`
230			`p0.eq br sgcfifo4`
231			`lb r4,hs:UART_MC ; set DTR`
232			`ori r4,r4,#1`
233			`sb r4,hs:UART_MC`
234			`sgcfifo4:`
235			`lb r4,Uart_rxxon`
236			`tst p0,r4`
237			`p0.eq br sgcfifo5`
238			`ldi r4,#XON`
239			`sb r4,hs:UART`
240			`sgcfifo5:`
241			`sgcfifo2: ; return with char in r1`
242			`lw r2,[sp]`
243			`lw r3,8[sp]`
244			`lw r4,16[sp]`
245			`lw r5,24[sp]`
246			`lws c1,32[sp]`
247			`addui sp,sp,#40`
248			`rts`
249			`sgcfifo1:`
250			`ldi r1,#-1 ; no char available`
251			`lw r2,[sp]`
252			`lw r3,8[sp]`
253			`lw r4,16[sp]`
254			`lw r5,24[sp]`
255			`lws c1,32[sp]`
256			`addui sp,sp,#40`
257			`rts`
258
259
260			`;-----------------------------------------`
261			`; Serial port IRQ`
262			`;-----------------------------------------`
263			`;`
264			`SerialIRQ:`
265			`sync`
266			`addui r31,r31,#-64`
267			`sw r1,[r31]`
268			`sw r2,8[r31]`
269			`sw r4,16[r31]`
270			`sws p0,24[r31]`
271			`sw r3,32[r31]`
272			`sws c1,40[r31]`
273			`sws hs,48[r31]`
274			`sws hs.lmt,56[r31]`
275			`ldis hs,#$FFD00000`
276			`ldis hs.lmt,#$100000`
277
278			`lb r1,hs:UART_IS ; get interrupt status`
279			`tst p0,r1`
280			`p0.gt br sirq1 ; no interrupt`
281			`andi r1,r1,#0x7f ; switch on interrupt type`
282			`biti p0,r1,#4`
283			`p0.ne br srxirq`
284			`biti p0,r1,#$0C`
285			`p0.ne br stxirq`
286			`biti p0,r1,#$10`
287			`p0.ne br smsirq`
288			`; unknown IRQ type`
289			`sirq1:`
290			`lw r1,[r31]`
291			`lw r2,8[r31]`
292			`lw r4,16[r31]`
293			`lws p0,24[r31]`
294			`lw r3,32[r31]`
295			`lws c1,40[r31]`
296			`lws hs,48[r31]`
297			`lws hs.lmt,56[r31]`
298			`addui r31,r31,#64`
299			`sync`
300			`rti`
301
302			`; Get the modem status and record it`
303			`smsirq:`
304			`lbu r1,hs:UART_MS`
305			`sb r1,Uart_ms`
306			`br sirq1`
307
308			`stxirq:`
309			`br sirq1`
310
311			`; Get a character from the uart and store it in the rx fifo`
312			`srxirq:`
313			`srxirq1:`
314			`lbu r1,hs:UART_RX ; get the char (clears interrupt)`
315			`lbu r3,Uart_txxon`
316			`tst p0,r3`
317			`p0.eq br srxirq3`
318			`cmpi p0,r1,#XOFF`
319			`p0.ne br srxirq2`
320			`ldi r1,#1`
321			`sb r1,Uart_txxonoff`
322			`br srxirq5`
323			`srxirq2:`
324			`cmpi p0,r1,#XON`
325			`p0.ne br srxirq3`
326			`sb r0,Uart_txxonoff`
327			`br srxirq5`
328			`srxirq3:`
329			`sb r0,Uart_txxonoff`
330			`lcu r4,Uart_rxhead`
331			`sb r1,Uart_rxfifo[r4] ; store in buffer`
332			`addui r4,r4,#1`
333			`andi r4,r4,#$1ff`
334			`sc r4,Uart_rxhead`
335			`srxirq5:`
336			`lb r1,hs:UART_LS ; check for another ready character`
337			`biti p0,r1,#1 ; check rxfull bit`
338			`p0.ne br srxirq1 ; loop back for another character`
339			`lb r1,Uart_rxflow ; are we using flow controls?`
340			`tst p0,r1`
341			`p0.ne br srxirq8`
342			`bsr CharsInRxBuf`
343			`lb r1,Uart_foff`
344			`cmp p0,r4,r1`
345			`p0.lt br srxirq8`
346			`ldi r1,#1`
347			`sb r1,Uart_rxflow`
348			`lb r1,Uart_rxrts`
349			`tst p0,r1`
350			`p0.eq br srxirq6`
351			`lb r1,hs:UART_MC`
352			`andi r1,r1,#$FD ; turn off RTS`
353			`sb r1,hs:UART_MC`
354			`srxirq6:`
355			`lb r1,Uart_rxdtr`
356			`tst p0,r1`
357
358			`p0.eq br srxirq7`
359			`lb r1,hs:UART_MC`
360			`andi r1,r1,#$FE ; turn off DTR`
361			`sb r1,hs:UART_MC`
362			`srxirq7:`
363			`lb r1,Uart_rxxon`
364			`tst p0,r1`
365			`p0.eq br srxirq8`
366			`ldi r1,#XOFF`
367			`sb r1,hs:UART_TX`
368			`srxirq8:`
369			`br sirq1`
370