; -*-asm-*-
include(`common.m4')

        BRA r :reset ; RESB
        NOP i        ; IRQ

        ;; reset stack
reset:  LDX # ff
        TXS i

        ;; Set pins 0-2 on Port A to Output
        LDA # %00000111
        STA a DDRA

        ;; Function Set:
        ;;  D7  D6  D5  D4  D3  D2  D1  D0
        ;;   0   0   1   B   L   F   x   x
        ;; (Bits 8/4, Lines 2/1, Font 5x11/5x8)
        LDA # %00111000
        JSR a :lcd-w-rs0

        ;; Display ON/OFF:
        ;;  D7  D6  D5  D4  D3  D2  D1  D0
        ;;   0   0   0   0   0   D   C   B
        ;; (Display, Cursor, Blink)
        LDA # %00001110
        JSR a :lcd-w-rs0

        ;; Clear Display:
        ;;  D7  D6  D5  D4  D3  D2  D1  D0
        ;;   0   0   0   0   0   0   0   1
        LDA # %00000001
        JSR a :lcd-w-rs0

        ;; Entry Mode Set:
        ;;  D7  D6  D5  D4  D3  D2  D1  D0
        ;;   0   0   0   0   0   1 I/D   S
        ;; (Increment/Decrement, Shift)
        LDA # %00000110
        JSR a :lcd-w-rs0

        ;; Set DDRAM Address:
        ;;  D7  D6  D5  D4  D3  D2  D1  D0
        ;;   1  A6  A5  A4  A3  A2  A1  A0
        LDA # hh(L_DDRAM|0)
        JSR a :lcd-w-rs0

        ;; Write Data:
        ;;  D7  D6  D5  D4  D3  D2  D1  D0
        ;;   D   D   D   D   D   D   D   D
        LDA # 0
        JSR a :lcd-w-rs1

        ;; Write Data:
        ;;  D7  D6  D5  D4  D3  D2  D1  D0
        ;;   D   D   D   D   D   D   D   D
        LDA # 1
        JSR a :lcd-w-rs1

        ;; Set CGRAM Address:
        ;;  D7  D6  D5  D4  D3  D2  D1  D0
        ;;   0   1 AC5 AC4 AC3 AC2 AC1 AC0
        LDA # hh(L_CGRAM|0)
        JSR a :lcd-w-rs0

        ;; data is at e000
        LDA # 00
        STA zp 00
        LDA # e0
        STA zp 01

        ;; 16
        LDX # 16
        LDY # 0

loop:   LDA (zp),y 00

        ;; Write Data to CGRAM
        ;;  D7  D6  D5  D4  D3  D2  D1  D0
        ;;   D   D   D   D   D   D   D   D
        ;; RS:1 RW:0
        STA a PORTB
        JSR a :lcd-w-rs1

        INY i
        DEX i
        BNE r :loop


        ;; Display ON/OFF:
        ;;  D7  D6  D5  D4  D3  D2  D1  D0
        ;;   0   0   0   0   0   D   C   B
        ;; (Display, Cursor, Blink)
        LDA # %00001100
        JSR a :lcd-w-rs0

        ;; Set CGRAM Address
        ;;  D7  D6  D5  D4  D3  D2  D1  D0
        ;;   0   1 AC5 AC4 AC3 AC2 AC1 AC0
loop2:  LDA # hh(L_CGRAM|9)
        JSR a :lcd-w-rs0

        ;; Write Data to CGRAM
        ;;  D7  D6  D5  D4  D3  D2  D1  D0
        ;;   D   D   D   D   D   D   D   D
        LDA # %00110
        JSR a :lcd-w-rs1

        ;; Set CGRAM Address
        ;;  D7  D6  D5  D4  D3  D2  D1  D0
        ;;   0   1 AC5 AC4 AC3 AC2 AC1 AC0
        LDA # hh(L_CGRAM|9)
        JSR a :lcd-w-rs0

        ;; Write Data to CGRAM
        ;;  D7  D6  D5  D4  D3  D2  D1  D0
        ;;   D   D   D   D   D   D   D   D
        LDA # %00000
        JSR a :lcd-w-rs1

        JMP a :loop2

stop:   JMP a :stop


        ;; write "instruction"
lcd-w-rs0:      JSR a :lcd-wait

                STA a PORTB
                LDA # 0
                STA a PORTA
                LDA # hh(L_E)
                STA a PORTA
                LDA # 0
                STA a PORTA
                RTS s

        ;; write "data" to lcd
lcd-w-rs1:      JSR a :lcd-wait

                STA a PORTB
                LDA # hh(L_RS)
                STA a PORTA
                LDA # hh(L_RS|L_E)
                STA a PORTA
                LDA # hh(L_RS)
                STA a PORTA
                RTS s

        ;; wait BF
lcd-wait:       PHA s

                LDA # %00000000  ;; Set pins 0-7 on Port B to Input
                STA a DDRB

_lcd_wait:      LDA # hh(L_RW)
                STA a PORTA
                LDA # hh(L_E|L_RW)
                STA a PORTA
                LDA a PORTB
                AND # %10000000
                BNE r :_lcd_wait

                LDA # hh(L_RW)
                STA a PORTA

                LDA # %11111111  ;; Set pins 0-7 on Port B to Output
                STA a DDRB

                PLA s
                RTS s