day 1

.gitignore

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+*.o
+a.out

01/Makefile

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+all:
+	nasm -g -felf32 main.s && ld -melf_i386 -g main.o
+

01/main.s

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+%define BUFF_LIM 32768
+
+;             call #  val  val2
+; int $0x80   eax     eax  edx  -
+;
+; arg1  arg2  arg3  arg4  arg5  arg6  arg7  
+; ebx   ecx   edx   esi   edi   ebp   -
+global _start
+[bits 32]
+[section .text]
+_start:
+push 0 ; eof
+mov eax, 5 ; open
+mov ebx, filename
+xor ecx, ecx ; read only
+int 0x80
+mov ebx, eax
+mov eax, 3 ; read
+mov ecx, read_buff
+mov edx, BUFF_LIM
+int 0x80
+cmp eax, -1 ; err
+je exit
+cmp eax, BUFF_LIM
+je .no_eof
+; we hit eof
+inc dword [esp]
+.no_eof:
+; parse section
+lea edi, [read_buff+eax]
+mov esi, read_buff
+.cont_read:
+xor ecx, ecx ; set if first is found
+; last digit in ebx
+xor ebx, ebx
+; counting loop
+xor eax, eax
+push eax ; first digit
+jmp .count_loop_cont
+.count_loop:
+lodsb
+cmp al, 10 ; newline
+je .next_line
+cmp al, '0'
+jl .count_loop_cont
+cmp al, '9'
+jg .check_str
+sub al, '0'
+; reset string parsing when we got a numeral
+call reset_string_wheels
+.matched:
+test ecx, ecx
+jnz .have_first
+mov [esp], eax ; first digit
+inc ecx
+.have_first:
+mov ebx, eax ; set last to current
+.count_loop_cont:
+cmp esi, edi
+jl .count_loop
+.next_line:
+test ecx, ecx
+jz .check_end ; no digits (huh?)
+pop eax ; first digit
+mov dl, 10
+mul dl
+add eax, ebx
+; add to total
+add [final_value], eax
+.check_end:
+; reset string parsing when we got a newline
+call reset_string_wheels
+; check for more data
+cmp esi, edi
+jl .cont_read
+; TODO handle files over BUFF_LIM bytes
+; check for EOF
+cmp dword [esp], 1
+jne .cont_read
+; we're at EOF, print result
+mov eax, [final_value]
+call print_dec
+jmp exit
+.check_str:
+call weird_string_parser
+; check result
+mov al, [matched_value]
+test al, al
+jnz .match_found
+; nothing matched yet
+; check if we got a word char
+cmp byte [matched_any_char], 1
+je .count_loop_cont
+; not a word char, reset wheels
+call reset_string_wheels
+jmp .count_loop_cont
+.match_found:
+; we have a match
+; reset the matched value
+; and go back to loop
+mov byte [matched_value], 0
+jmp .matched
+
+reset_string_wheels:
+push edi
+push ecx
+push eax
+mov edi, number_wheels
+mov ecx, number_lens - number_wheels
+xor eax, eax
+rep stosb
+pop eax
+pop ecx
+pop edi
+ret
+
+exit:
+mov eax, 1
+int 0x80    ; exit
+
+; i hate this
+print_dec:
+sub esp, 12
+lea ecx, [esp+11]
+test eax, eax
+jz .zero
+mov esi, 0
+mov ebx, 10
+.div_shit:
+xor edx, edx
+div ebx
+dec ecx
+inc esi
+add dl, '0'
+mov byte [ecx], dl
+test eax, eax
+jnz .div_shit
+mov edx, esi
+jmp .write
+.zero:
+mov byte [esp+10], 0
+lea ecx, [esp+10]
+mov edx, 1 ; count
+.write:
+mov eax, 4 ; write
+mov ebx, 1 ; stdout
+int 0x80
+add esp, 12
+ret
+
+; i'm in hell
+weird_string_parser:
+pushad
+; reset matched any char
+mov byte [matched_any_char], 0
+mov edi, number_wheels
+mov esi, number_lens
+mov ebp, numbers
+mov ecx, 0
+.test_loop:
+mov edx, ebp
+; add current wheel value
+movzx ebx, byte [edi]
+add edx, ebx
+; compare to input
+cmp byte [edx], al
+jne .next_test_fail
+; match - increment counter
+inc bl
+; test against length
+cmp byte [esi], bl
+je .full_match
+.partial_match:
+; partial match - save value
+mov [edi], bl
+; we matched any char
+mov byte [matched_any_char], 1
+jmp .next_test_match
+.next_test_fail:
+; reset the current wheel
+mov byte [edi], 0
+; check if it's the start of the word
+cmp byte [ebp], al
+jne .next_test_match ; nope
+; yep! save
+mov bl, 1
+jmp .partial_match
+.next_test_match:
+inc ecx
+; check if we're done testing
+cmp ecx, 9
+jge .done
+; add current value length to string
+movzx ebx, byte [esi]
+add ebp, ebx
+inc edi
+inc esi
+; loop
+jmp .test_loop
+.done:
+popad
+ret
+.full_match:
+; save matched byte
+inc ecx ; zero -> one
+mov byte [matched_value], cl
+; reset this wheel
+mov byte [edi], 0
+; next check
+jmp .next_test_match
+
+[section .data]
+final_value: dd 0
+matched_value: db 0
+matched_any_char: db 0
+number_wheels: db 0,0,0,0,0,0,0,0,0
+number_lens: db 3,3,5,4,4,3,5,5,4
+numbers: db "onetwothreefourfivesixseveneightnine"
+filename: db "input",0
+
+[section .bss]
+read_buff: resb BUFF_LIM

01/main_part1.s

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+%define BUFF_LIM 32768
+
+;             call #  val  val2
+; int $0x80   eax     eax  edx  -
+;
+; arg1  arg2  arg3  arg4  arg5  arg6  arg7  
+; ebx   ecx   edx   esi   edi   ebp   -
+global _start
+[bits 32]
+[section .text]
+_start:
+push 0 ; eof
+mov eax, 5 ; open
+mov ebx, filename
+xor ecx, ecx ; read only
+int 0x80
+mov ebx, eax
+mov eax, 3 ; read
+mov ecx, read_buff
+mov edx, BUFF_LIM
+int 0x80
+cmp eax, -1 ; err
+je exit
+cmp eax, BUFF_LIM
+je .no_eof
+; we hit eof
+inc dword [esp]
+.no_eof:
+; parse section
+lea edi, [read_buff+eax]
+mov esi, read_buff
+.cont_read:
+xor ecx, ecx ; set if first is found
+; last digit in ebx
+xor ebx, ebx
+; counting loop
+xor eax, eax
+push eax ; first digit
+jmp .count_loop_cont
+.count_loop:
+lodsb
+cmp al, 10 ; newline
+je .next_line
+sub al, '0'
+js .count_loop_cont
+cmp al, 9
+jg .count_loop_cont
+test ecx, ecx
+jnz .have_first
+mov [esp], eax ; first digit
+inc ecx
+.have_first:
+mov ebx, eax ; set last to current
+.count_loop_cont:
+cmp esi, edi
+jl .count_loop
+.next_line:
+test ecx, ecx
+jz .cont_read ; no digits!
+pop eax ; first digit
+mov dl, 10
+mul dl
+add eax, ebx
+; add to total
+add [final_value], eax
+; check for more data
+cmp esi, edi
+jl .cont_read
+; TODO handle files over BUFF_LIM bytes
+; check for EOF
+cmp dword [esp], 1
+jne .cont_read
+; we're at EOF, print result
+mov eax, [final_value]
+call print_dec
+jmp exit
+
+exit:
+mov eax, 1
+int 0x80    ; exit
+
+; i hate this
+print_dec:
+sub esp, 12
+lea ecx, [esp+11]
+test eax, eax
+jz .zero
+mov esi, 0
+mov ebx, 10
+.div_shit:
+xor edx, edx
+div ebx
+dec ecx
+inc esi
+add dl, '0'
+mov byte [ecx], dl
+test eax, eax
+jnz .div_shit
+mov edx, esi
+jmp .write
+.zero:
+mov byte [esp+10], 0
+lea ecx, [esp+10]
+mov edx, 1 ; count
+.write:
+mov eax, 4 ; write
+mov ebx, 1 ; stdout
+int 0x80
+add esp, 12
+ret
+
+[section .data]
+final_value: dd 0
+filename: db "input",0
+
+[section .bss]
+read_buff: resb BUFF_LIM

README.md

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+# advent of code 2023
+i'm doing this in assembly
+bc masochism or something
+i'm dying
+why
+