223 lines
4.3 KiB
NASM
223 lines
4.3 KiB
NASM
// vim: filetype=kickass
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* = * "Day 01"
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//
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// day01
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//
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// Destroys:
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// a, x, y, $02..$04, $10..$1c, $20..$25, $fd..$fe, everything you've ever loved
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//
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.const input_pointer = $20
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.const atoi_result = $03 // Needs to be $03 for tree_insert
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.const loop_pointer = $20
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.const remainder = $24
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// Need to be $26 and $fd due to multiply_16bit_unsigned
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.const outer_value = $26
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.const inner_value = $fd
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day01:
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jsr tree_clear
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move_16_imm($03, str_title)
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jsr write_string
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//
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// Parse the input at day01_input into an array of integers.
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//
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move_16_imm(input_pointer, day01_input)
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ldy #0
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lda #0
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sta zp_temp
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!line:
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// Create a temporary 16-bit integer to store the result in
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// in between digits.
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move_16_imm(atoi_result, 0)
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!digit:
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// Check for the newline character at the end of the line.
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lda (input_pointer), y
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cmp #'\n'
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beq !newline+
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// Multiply the stored number by 10.
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i16_mul10(atoi_result)
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// Subtract '0' from the current digit to convert it to "binary".
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lda (input_pointer), y
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sec
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sbc #'0'
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// Add the binary digit to the stored number
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i16_i8_add_a(atoi_result)
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// Increment y.
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iny
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bne !digit-
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// If y overflows, increment the MSB of the input pointer as well,
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// for a 16-bit increment.
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inc input_pointer + 1
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jmp !digit-
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!newline:
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// Insert the converted number into the tree.
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jsr tree_insert
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iny
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bne !+
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inc input_pointer + 1
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!:
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// Check for the null terminator.
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lda (input_pointer), y
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bne !line-
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//
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// Part 1
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//
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ldy #0
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!loop:
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// Subtract the number from 2020 to find the needed value.
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lda tree_values_lo, y
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sta $fd
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eor #$ff
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sec
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adc #<2020
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sta $03
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sta $26
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lda tree_values_hi, y
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sta $fe
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eor #$ff
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adc #>2020
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sta $04
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sta $27
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iny
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jsr tree_contains
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bne !loop-
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// Multiply the results together
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sec
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jsr multiply_16bit_unsigned
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// Print the 32-bit result as decimal.
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lda $25
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sta udivmod32_dividend + 3
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lda $24
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sta udivmod32_dividend + 2
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lda $23
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sta udivmod32_dividend + 1
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lda $22
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sta udivmod32_dividend + 0
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jsr print_decimal_u32
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move_16_imm($03, str_part2)
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jsr write_string
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.const val_a = $26
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.const val_b = $fd
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.const val_c = $44
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.const val_temp = $46
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.const outer_i = $1f
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//
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// Part 2
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//
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ldx #0
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!outer_loop:
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ldy #0
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lda tree_values_lo, x
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sta val_a + 0
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lda tree_values_hi, x
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sta val_a + 1
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stx outer_i
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!inner_loop:
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// Subtract the numbers from 2020 to find the needed value.
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lda tree_values_lo, y
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sta val_b + 0
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bne !not_zero+
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lda tree_values_hi, y
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bne !not_zero+
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ldx outer_i
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inx
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bne !outer_loop-
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!not_zero:
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lda tree_values_hi, y
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sta val_b + 1
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lda val_a + 0
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clc
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adc val_b + 0
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sta val_temp + 0
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lda val_a + 1
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adc val_b + 1
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sta val_temp + 1
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lda val_temp + 0
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eor #$ff
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sec
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adc #<2020
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sta $03
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sta val_c + 0
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lda val_temp + 1
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eor #$ff
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adc #>2020
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sta $04
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sta val_c + 1
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iny
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jsr tree_contains
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bne !inner_loop-
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// Multiply the three numbers together
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sec
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jsr multiply_16bit_unsigned
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u16_u16_move($30, $22)
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u16_u16_move($32, $24)
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u16_u16_move($34, val_c)
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move_16_imm($36, 0)
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jsr multiply_32bit_unsigned
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// Print the 32-bit result as decimal.
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u16_u16_move(udivmod32_dividend, $38)
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u16_u16_move(udivmod32_dividend + 2, $3a)
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u16_u16_move(udivmod32_dividend + 4, $3c)
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u16_u16_move(udivmod32_dividend + 6, $3e)
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jsr print_decimal_u32
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move_16_imm($03, str_done)
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jsr write_string
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rts
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str_title:
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.text "# Day 01"
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.byte '\n', '\n'
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.text "Part 1: "
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.byte 0
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str_part2:
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.byte '\n'
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.text "Part 2: "
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.byte 0
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str_done:
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.byte '\n', '\n'
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.text "* Done"
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.byte '\n', 0
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