2020/c64/day02.asm

// vim: filetype=kickass

* = * "Day 02 Input"
!input:
    .import binary "../inputs/02"
    .byte 0

!str_title:
    .text "# Day 02"
    .byte '\n', '\n'
    .text "Part 1: "
    .byte 0

* = * "Day 02 Code"
day02:
{
.const input_pointer = $40
.const range_low     = $42
.const range_high    = $43
.const letter        = $44
.const is_valid      = $45
.const valid_count   = $46

{
    move_16_imm($03, !str_title-)
    jsr write_string

.break
    move_16_imm(input_pointer, !input-)

    ldy #0
    sty valid_count + 0
    sty valid_count + 1

part1_loop:
    jsr parse_rule
    beq part1_done

    // Increment range_high so we can beq.
    inc range_high
    // Decrement range_low so it overflows on invalid passwords
    dec range_low

password:
    lda (input_pointer), y
    y_buf_inc(input_pointer)
    cmp #$0a
    beq newline
    cmp letter
    bne password

    dec range_low
    dec range_high
    bne password

    // range_high went to 0, so it contains the letter too many times
    // Skip to newline, then loop back around.
    !:
        lda (input_pointer), y
        y_buf_inc(input_pointer)
        cmp #$0a
    bne !-
    jmp part1_loop

newline:
    // If range_low is positive, we didn't meet the minimum
    lda range_low
    bpl part1_loop

    inc valid_count + 0
    bne part1_loop
    inc valid_count + 1
    jmp part1_loop

part1_done:
.break
    lda valid_count + 0; sta udivmod32_dividend + 0
    lda valid_count + 1; sta udivmod32_dividend + 1
    lda #0
    sta udivmod32_dividend + 2
    sta udivmod32_dividend + 3
    jsr print_decimal_u32
}

{
    move_16_imm($03, str_part2)
    jsr write_string

.break
    move_16_imm(input_pointer, !input-)

    ldy #0
    sty valid_count + 0
    sty valid_count + 1

part2_loop:
    jsr parse_rule
    beq part2_done

    lda #0
    sta is_valid

password:
    lda (input_pointer), y
    tax
    y_buf_inc(input_pointer)
    cmp #$0a
    beq newline

    dec range_low
    bne !+
    cmp letter
    bne !+
        lda #1
        eor is_valid
        sta is_valid
    !:

    dec range_high
    bne !+++
        txa
        cmp letter
        bne !+
            lda #1
            eor is_valid
            sta is_valid
        !:

        // If we checked both numbers, we can skip the rest of the password.
        !:
            lda (input_pointer), y
            y_buf_inc(input_pointer)
            cmp #$0a
        bne !-
        jmp newline
    !:

    jmp password

newline:
    lda is_valid
    beq part2_loop

    inc valid_count + 0
    bne part2_loop
    inc valid_count + 1
    jmp part2_loop

part2_done:
.break
    lda valid_count + 0; sta udivmod32_dividend + 0
    lda valid_count + 1; sta udivmod32_dividend + 1
    lda #0
    sta udivmod32_dividend + 2
    sta udivmod32_dividend + 3
    jsr print_decimal_u32
}

    move_16_imm($03, str_done)
    jsr write_string

    ldy #0
    !:
        ldx #0
        !: inx; bne !-
        !: inx; bne !-
        !: inx; bne !-
        !: inx; bne !-
        iny
    bne !-----

    lda #1
    sta $d020

    ldy #0
    !:
        ldx #0
        !: inx; bne !-
        !: inx; bne !-
        iny
    bne !---

    sta $d021

    ldy #0
    !:
        ldx #0
        !: inx; bne !-
        !: inx; bne !-
        !: inx; bne !-
        iny
    bne !----
{
    .const timer = $40
    .const xvel = $41


    lda #(sprite1 / 64)
    sta $07f8
    lda #(sprite2 / 64)
    sta $07f9
    lda #(sprite3 / 64)
    sta $07fa
    lda #(sprite4 / 64)
    sta $07fb

    lda #0
    sta $d001  // TL y
    sta $d003  // TR y

    lda #0
    sta $d005  // BL y
    sta $d007  // BR y

    lda #0
    sta $d000  // TL x
    sta $d004  // BL x

    lda #48
    sta $d002  // TR x
    sta $d006  // BR x

    lda #0
    sta $d010

    lda #$0f
    sta $d015  // sprite enable
    sta $d01c  // enable multicolor
    sta $d01d  // double width
    sta $d017  // double height

    lda #$09
    sta $d025
    lda #$08
    sta $d026

    lda #$00
    sta $d027
    sta $d028
    sta $d029
    sta $d02a

    lda #0
    sta timer
    lda #127
    sta xvel

    SetRasterInterrupt(raster_irq)
    cli

    jmp *

raster_irq:
    pha
    txa
    pha
    tya
    pha

    dec timer
    beq !+
        jmp done
    !:
    lda #200
    sta timer

    // 0-214: Move bottom sprites
    inc $d005
    inc $d007
    bne !+
        // If they wrap around, disable them
        lda $d015
        and #%0011
        sta $d015
    !:

    // 42-256: Move top sprites
    // if top_sprite.disabled || top_sprite.y >= 42
    lda $d015
    and #$08
    beq !+
        lda $d007
        cmp #42
        bcc !++
    !:
        inc $d001
        inc $d003
    bne !+
        // If they wrap around, disable them
        lda $d015
        and #%1100
        sta $d015
    !:


    lda xvel
    beq !+
        jmp no_flip
    !:
        // If velocity is negative, flip the sprites
        ldy #63
        flip_loop:
            //
            // Sprite 1
            //
            lda sprite1 - 3, y
            sta zp_temp

            ldx sprite1 - 1, y
            lda flip_map, x
            sta sprite1 - 3, y

            ldx zp_temp
            lda flip_map, x
            sta sprite1 - 1, y

            ldx sprite1 - 2, y
            lda flip_map, x
            sta sprite1 - 2, y

            //
            // Sprite 2
            //
            lda sprite2 - 3, y
            sta zp_temp

            ldx sprite2 - 1, y
            lda flip_map, x
            sta sprite2 - 3, y

            ldx zp_temp
            lda flip_map, x
            sta sprite2 - 1, y

            ldx sprite2 - 2, y
            lda flip_map, x
            sta sprite2 - 2, y

            //
            // Sprite 3
            //
            lda sprite3 - 3, y
            sta zp_temp

            ldx sprite3 - 1, y
            lda flip_map, x
            sta sprite3 - 3, y

            ldx zp_temp
            lda flip_map, x
            sta sprite3 - 1, y

            ldx sprite3 - 2, y
            lda flip_map, x
            sta sprite3 - 2, y

            //
            // Sprite 4
            //
            lda sprite4 - 3, y
            sta zp_temp

            ldx sprite4 - 1, y
            lda flip_map, x
            sta sprite4 - 3, y

            ldx zp_temp
            lda flip_map, x
            sta sprite4 - 1, y

            ldx sprite4 - 2, y
            lda flip_map, x
            sta sprite4 - 2, y

            dey; dey; dey
        beq !+
            jmp flip_loop
        !:

        lda $d000; clc; adc #48; sta $d000; sta $d004
        lda $d002; sec; sbc #48; sta $d002; sta $d006
    no_flip:

    lda xvel
    cmp #$80; ror
    cmp #$80; ror
    cmp #$80; ror
    cmp #$80; ror
    cmp #$80; ror
    tax

    // Move left sprites
    txa; clc; adc $d000; sta $d000; sta $d004
    bne !+
        // If they wrap around, disable them
        lda $d015
        and #%1010
        sta $d015
    !:

    // Move right sprites
    txa; clc; adc $d002; sta $d002; sta $d006
    bne !+
        // If they wrap around, disable them
        lda $d015
        and #%0101
        sta $d015
    !:

    dec xvel

done:
    pla
    tay
    pla
    tax
    pla
    rti
}

mul10:
    asl
    sta zp_temp
    asl
    asl
    adc zp_temp
    rts

parse_rule:
low_number:
    // 13-16 k: kkkkkgmkbvkkrskhd
    // ^^^
    lda (input_pointer), y
    bne !+
        // Check for null terminator
        rts
    !:
    y_buf_inc(input_pointer)
    sec; sbc #'0'
    sta range_low

    lda (input_pointer), y
    y_buf_inc(input_pointer)
    cmp #$2d
    beq !+
        tax
        lda range_low
        jsr mul10
        sta range_low
        txa

        sec; sbc #'0'
        clc; adc range_low
        sta range_low

        y_buf_inc(input_pointer)
    !:

high_number:
    // 13-16 k: kkkkkgmkbvkkrskhd
    //    ^^^
    lda (input_pointer), y
    y_buf_inc(input_pointer)
    sec; sbc #'0'
    sta range_high

    lda (input_pointer), y
    y_buf_inc(input_pointer)
    cmp #$20
    beq !+
        tax
        lda range_high
        jsr mul10
        sta range_high
        txa

        sec; sbc #'0'
        clc; adc range_high
        sta range_high

        y_buf_inc(input_pointer)
    !:

    //
    // 13-16 k: kkkkkgmkbvkkrskhd
    //       ^^^
    //
    lda (input_pointer), y
    sta letter

    // TODO adc #3 instead?
    y_buf_inc(input_pointer)
    y_buf_inc(input_pointer)
    y_buf_inc(input_pointer)

    lda #1
    rts


}