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114 lines
2.3 KiB
114 lines
2.3 KiB
;
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;==================================================================================================
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; UART DRIVER (SERIAL PORT)
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;==================================================================================================
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;
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UART0_DIV .EQU (1843200 / (16 * BAUDRATE))
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;
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; CHARACTER DEVICE DRIVER ENTRY
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; A: RESULT (OUT), CF=ERR
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; B: FUNCTION (IN)
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; C: CHARACTER (IN/OUT)
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; E: DEVICE/UNIT (IN)
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;
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;
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UART_DISPATCH:
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LD A,B ; GET REQUESTED FUNCTION
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AND $0F ; ISOLATE SUB-FUNCTION
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JP Z,UART0_IN
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DEC A
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JP Z,UART0_OUT
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DEC A
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JP Z,UART0_IST
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DEC A
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JP Z,UART0_OST
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CALL PANIC
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;
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;
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;
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UART_INIT:
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PRTS("UART0: IO=0x$")
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LD A,SIO_BASE
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CALL PRTHEXBYTE
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PRTS(" BAUD=$")
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LD HL,BAUDRATE / 10
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CALL PRTDEC
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PRTC('0')
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LD A,80H
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OUT (SIO_LCR),A ; DLAB ON
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LD A,UART0_DIV
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OUT (SIO_DLL),A ; SET DIVISOR (LS)
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LD A,00H
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OUT (SIO_DLM),A ; SET DIVISOR (MS)
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LD B,03H ; B = DEFAULT SETTING FOR MCR (DTR + RTS)
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#IF (UARTAFC)
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PRTS(" AFC$")
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LD A,$55 ; TEST VALUE
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OUT (SIO_SCR),A ; SET SCRATCH REG TO TEST VALUE
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LD A,0BFH
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OUT (SIO_LCR),A ; SET LCR=$BF TO ATTEMPT TO ACCESS EFR
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IN A,(SIO_SCR) ; READ SCRATCH REGISTER
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CP $55 ; IF $55, NO EFR
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JR NZ,UART_AFC1 ; NZ, HAVE EFR, DO IT
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SET 5,B ; ENABLE AUTO FLOW CONTROL
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JR UART_AFC2
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UART_AFC1:
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LD A,0C0H ; ENABLE CTS/RTS FLOW CONTROL
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OUT (SIO_EFR),A ; SAVE IT
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UART_AFC2:
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#ENDIF
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LD A,03H
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OUT (SIO_LCR),A ; DLAB OFF, 8 DATA, 1 STOP, NO PARITY
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LD A,B ; LOAD MCR VALUE TO SET
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OUT (SIO_MCR),A ; SAVE IT
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#IF (UARTFIFO)
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; LD A,07H ; ENABLE AND RESET FIFOS
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LD A,01H ; ENABLE AND RESET FIFOS
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OUT (SIO_FCR),A ; ENABLE FIFOS
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PRTS(" FIFO$")
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#ENDIF
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RET
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;
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;
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;
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UART0_IN:
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CALL UART0_IST
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OR A
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JR Z,UART0_IN
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IN A,(SIO_RBR) ; READ THE CHAR FROM THE UART
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LD E,A
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RET
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;
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;
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;
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UART0_IST:
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IN A,(SIO_LSR) ; READ LINE STATUS REGISTER
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AND $01 ; TEST IF DATA IN RECEIVE BUFFER
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JP Z,CIO_IDLE ; DO IDLE PROCESSING AND RETURN
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XOR A
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INC A ; SIGNAL CHAR READY, A = 1
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RET
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;
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;
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;
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UART0_OUT:
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CALL UART0_OST
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OR A
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JR Z,UART0_OUT
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LD A,E
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OUT (SIO_THR),A ; THEN WRITE THE CHAR TO UART
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RET
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;
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UART0_OST:
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IN A,(SIO_LSR) ; READ LINE STATUS REGISTER
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AND $20
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JP Z,CIO_IDLE ; DO IDLE PROCESSING AND RETURN
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XOR A
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INC A ; SIGNAL BUFFER EMPTY, A = 1
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RET
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