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[/] [thor/] [trunk/] [software/] [source/] [serial.asm] - Rev 54
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UART EQU 0xC0A00UART_TX EQU 0xC0A00UART_RX EQU 0xC0A00UART_LS EQU 0xC0A01UART_MS EQU 0xC0A02UART_IS EQU 0xC0A03UART_IE EQU 0xC0A04UART_FF EQU 0xC0A05UART_MC EQU 0xC0A06UART_CTRL EQU 0xC0A07UART_CM0 EQU 0xC0A08UART_CM1 EQU 0xC0A09UART_CM2 EQU 0xC0A0AUART_CM3 EQU 0xC0A0BUART_SPR EQU 0xC0A0F;------------------------------------------------------------------------------;------------------------------------------------------------------------------;==============================================================================; Serial port;==============================================================================code;------------------------------------------------------------------------------; Initialize UART;------------------------------------------------------------------------------align 8ser_jmp:jmp SerialIRQ[c0]SerialInit:addui sp,sp,#-8sws c1,[sp]ldis hs,#$FFD00000ldis 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 baudldi r1,#$00C9539B ; constant for clock multiplier with 50.0MHz clock for 9600 baudshrui r1,r1,#8 ; drop the LSB (not used)sb r1,hs:UART_CM1shrui r1,r1,#8sb r1,hs:UART_CM2shrui r1,r1,#8sb r1,hs:UART_CM3sb r0,hs:UART_CTRL ; no hardware flow controlsc r0,Uart_rxhead ; reset buffer indexessc r0,Uart_rxtailldi r1,#0x1f0sc r1,Uart_foff ; set threshold for XOFFldi r1,#0x010sc r1,Uart_fon ; set threshold for XONldi r1,#1sb r1,hs:UART_IE ; enable receive interrupt onlysb r0,Uart_rxrts ; no RTS/CTS signals availablesb r0,Uart_txrts ; no RTS/CTS signals availablesb r0,Uart_txdtr ; no DTR signals availablesb r0,Uart_rxdtr ; no DTR signals availableldi r1,#1sb r1,Uart_txxon ; for nowldi r1,#1; sb r1,SERIAL_SEMA; setup IRQ vectorlla r1,cs:ser_jmpldi r2,#199bsr set_vectorlws c1,[sp]addui sp,sp,#8rts;---------------------------------------------------------------------------------; Get character directly from serial port. Blocks until a character is available.;---------------------------------------------------------------------------------;SerialGetCharDirect:sgc1:lvb r1,hs:UART_LS ; uart statusbiti p0,r1,#1 ; is there a char available ?p0.eq br sgc1lvb r1,hs:UART_RXrts;------------------------------------------------; Check for a character at the serial port; returns r1 = 1 if char available, 0 otherwise;------------------------------------------------;SerialCheckForCharDirect:lvb r1,hs:UART_LS ; uart statusandi r1,r1,#rxfull ; is there a char available ?rts;-----------------------------------------; Put character to serial port; r1 = char to put;-----------------------------------------;SerialPutChar:addui sp,sp,#-48sw 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_MCori r2,r2,#3 ; assert DTR / RTSsb r2,hs:UART_MClb r2,Uart_txrtstst p0,r2p0.eq br spcb1lw r4,Millisecondsldis lc,#999 ; delay count (1 s)spcb3:lvb r2,hs:UART_MSbiti p0,r2,#$10 ; is CTS asserted ?p0.ne br spcb1lw r5,Millisecondscmp p0,r4,r5p0.eq br spcb3mov r4,r5loop spcb3br spcabortspcb1:lb r2,Uart_txdtrtst p0,r2p0.eq br spcb2lw r4,Millisecondsldis lc,#999 ; delay countspcb4:lvb r2,hs:UART_MSbiti p0,r2,#$20 ; is DSR asserted ?p0.ne br spcb2lw r5,Millisecondscmp p0,r4,r5p0.eq br spcb4mov r4,r5loop spcb4br spcabortspcb2:lb r2,Uart_txxontst p0,r2p0.eq br spcb5spcb6:lb r2,Uart_txxonofftst p0,r2p0.eq br spcb5lvb r4,hs:UART_MSbiti p0,r4,#0x80 ; DCD ?p0.ne br spcb6spcb5:lw r4,Millisecondsldis lc,#999 ; wait up to 1sspcb8:lvb r2,hs:UART_LSbiti p0,r2,#0x20 ; tx not full ?p0.ne br spcb7lw r5,Millisecondscmp p0,r4,r5p0.eq br spcb8mov r4,r5loop spcb8br spcabortspcb7:sb r1,hs:UART_TXspcabort: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,#40rts;-------------------------------------------------; Compute number of characters in recieve buffer.; r4 = number of chars;-------------------------------------------------CharsInRxBuf:lcu r4,Uart_rxheadlcu r3,Uart_rxtailsubu r4,r4,r3tst p0,r4p0.gt br cirxb1ldi r4,#0x200addu r4,r4,r3lcu r3,Uart_rxheadsubu r4,r4,r3cirxb1:rts;----------------------------------------------; Get character from rx fifo; If the fifo is empty enough then send an XON;----------------------------------------------;SerialGetChar:addui sp,sp,#-40sw r2,[sp]sw r3,8[sp]sw r4,16[sp]sw r5,24[sp]sws c1,32[sp]lcu r3,Uart_rxheadlcu r2,Uart_rxtailcmp p0,r2,r3p0.eq br sgcfifo1 ; is there a char available ?lbu r1,Uart_rxfifo[r2] ; get the char from the fifo into r1addui r2,r2,#1 ; increment the fifo pointerandi r2,r2,#$1ffsc r2,Uart_rxtaillb r2,Uart_rxflow ; using flow control ?tst p0,r2p0.eq br sgcfifo2lcu r3,Uart_fon ; enough space in Rx buffer ?bsr CharsInRxBufcmp p0,r4,r3p0.gt br sgcfifo2sb r0,Uart_rxflow ; flow offlb r4,Uart_rxrtstst p0,r4p0.eq br sgcfifo3lb r4,hs:UART_MC ; set rts bit in MCori r4,r4,#2sb r4,hs:UART_MCsgcfifo3:lb r4,Uart_rxdtrtst p0,r4p0.eq br sgcfifo4lb r4,hs:UART_MC ; set DTRori r4,r4,#1sb r4,hs:UART_MCsgcfifo4:lb r4,Uart_rxxontst p0,r4p0.eq br sgcfifo5ldi r4,#XONsb r4,hs:UARTsgcfifo5:sgcfifo2: ; return with char in r1lw r2,[sp]lw r3,8[sp]lw r4,16[sp]lw r5,24[sp]lws c1,32[sp]addui sp,sp,#40rtssgcfifo1:ldi r1,#-1 ; no char availablelw r2,[sp]lw r3,8[sp]lw r4,16[sp]lw r5,24[sp]lws c1,32[sp]addui sp,sp,#40rts;-----------------------------------------; Serial port IRQ;-----------------------------------------;SerialIRQ:syncaddui r31,r31,#-64sw r1,[r31]sw r2,8[r31]sw r4,16[r31]sws p0,24[r31]sw r3,32[r31]sws c1,40[r31]sws hs,48[r31]sws hs.lmt,56[r31]ldis hs,#$FFD00000ldis hs.lmt,#$100000lb r1,hs:UART_IS ; get interrupt statustst p0,r1p0.gt br sirq1 ; no interruptandi r1,r1,#0x7f ; switch on interrupt typebiti p0,r1,#4p0.ne br srxirqbiti p0,r1,#$0Cp0.ne br stxirqbiti p0,r1,#$10p0.ne br smsirq; unknown IRQ typesirq1: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,#64syncrti; Get the modem status and record itsmsirq:lbu r1,hs:UART_MSsb r1,Uart_msbr sirq1stxirq:br sirq1; Get a character from the uart and store it in the rx fifosrxirq:srxirq1:lbu r1,hs:UART_RX ; get the char (clears interrupt)lbu r3,Uart_txxontst p0,r3p0.eq br srxirq3cmpi p0,r1,#XOFFp0.ne br srxirq2ldi r1,#1sb r1,Uart_txxonoffbr srxirq5srxirq2:cmpi p0,r1,#XONp0.ne br srxirq3sb r0,Uart_txxonoffbr srxirq5srxirq3:sb r0,Uart_txxonofflcu r4,Uart_rxheadsb r1,Uart_rxfifo[r4] ; store in bufferaddui r4,r4,#1andi r4,r4,#$1ffsc r4,Uart_rxheadsrxirq5:lb r1,hs:UART_LS ; check for another ready characterbiti p0,r1,#1 ; check rxfull bitp0.ne br srxirq1 ; loop back for another characterlb r1,Uart_rxflow ; are we using flow controls?tst p0,r1p0.ne br srxirq8bsr CharsInRxBuflb r1,Uart_foffcmp p0,r4,r1p0.lt br srxirq8ldi r1,#1sb r1,Uart_rxflowlb r1,Uart_rxrtstst p0,r1p0.eq br srxirq6lb r1,hs:UART_MCandi r1,r1,#$FD ; turn off RTSsb r1,hs:UART_MCsrxirq6:lb r1,Uart_rxdtrtst p0,r1p0.eq br srxirq7lb r1,hs:UART_MCandi r1,r1,#$FE ; turn off DTRsb r1,hs:UART_MCsrxirq7:lb r1,Uart_rxxontst p0,r1p0.eq br srxirq8ldi r1,#XOFFsb r1,hs:UART_TXsrxirq8:br sirq1
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