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Rev Author Line No. Line
1004 dimkam 1 
    MODULE Uart
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UART_DATA_REG = #c6
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UART_STAT_REG = #c7
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UART_BYTE_RECIVED = #80
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UART_BYTE_SENDING = #40
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SCANDBLCTRL_REG = #0B
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ZXUNO_ADDR = #FC3B
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ZXUNO_REG = #FD3B
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; Enable UART
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; Cleaning all flags by reading UART regs
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; Wastes AF and BC
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init:
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    ld bc, ZXUNO_ADDR : ld a, UART_STAT_REG : out (c), a
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    ld bc, ZXUNO_REG : in A, (c)
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    ld bc, ZXUNO_ADDR : ld a, UART_DATA_REG : out (c), a
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    ld bc, ZXUNO_REG : in A, (c)
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    ld b, #ff
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.loop
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    push bc
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    call uartRead
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    pop bc
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    djnz .loop
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    ret
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read:
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    call uartRead
1346 alone 29 
    jr nc, read
1004 dimkam 30 
    ret
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; Write single byte to UART
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; A - byte to write
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; BC will be wasted
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write:    
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    push af
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    ld bc, ZXUNO_ADDR : ld a, UART_STAT_REG : out (c), a
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    ld bc, ZXUNO_REG : in A, (c) : and UART_BYTE_RECIVED
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    jr nz, .is_recvF
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.checkSent
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    ld bc, ZXUNO_REG : in A, (c) : and UART_BYTE_SENDING
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    jr nz, .checkSent
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    ld bc, ZXUNO_ADDR : ld a, UART_DATA_REG : out (c), a
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    ld bc, ZXUNO_REG : pop af : out (c), a
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    ret
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.is_recvF
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    push af : push hl
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    ld hl, is_recv : ld a, 1 : ld (hl), a
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    pop hl : pop af
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    jr .checkSent
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; Read byte from UART
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; A: byte
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; B:
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;     1 - Was read
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;     0 - Nothing to read
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uartRead:
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    ld a, (poked_byte) : and 1 : jr nz, .retBuff
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    ld a, (is_recv) : and 1 : jr nz, recvRet
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    ld bc, ZXUNO_ADDR : ld a, UART_STAT_REG : out (c), a
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    ld bc, ZXUNO_REG : in a, (c) : and UART_BYTE_RECIVED
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    jr nz, retReadByte
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    or a
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    ret
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.retBuff
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    ld a, 0 : ld (poked_byte), a : ld a, (byte_buff)
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    scf
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    ret
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retReadByte:
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    xor a : ld (poked_byte), a : ld (is_recv), a
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    ld bc, ZXUNO_ADDR : ld a, UART_DATA_REG : out (c), a
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    ld bc, ZXUNO_REG : in a, (c)
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    scf
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    ret
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recvRet:
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    ld bc, ZXUNO_ADDR : ld a,  UART_DATA_REG : out (c),a
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    ld bc, ZXUNO_REG : in a, (c)
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    ld hl, is_recv : ld (hl), 0
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    ld hl, poked_byte : ld (hl), 0
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    scf
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    ret
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poked_byte defb 0
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byte_buff defb 0
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is_recv defb 0
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    ENDMODULE