ProjectEulerNASM/011.asm at master · Roybie/ProjectEulerNASM · GitHub

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;Project Euler Problem #11
;https://projecteuler.net/problem=11

extern printf

section .data

    arr dq 08,02,22,97,38,15,00,40,00,75,04,05,07,78,52,12,50,77,91,08
        dq 49,49,99,40,17,81,18,57,60,87,17,40,98,43,69,48,04,56,62,00
        dq 81,49,31,73,55,79,14,29,93,71,40,67,53,88,30,03,49,13,36,65
        dq 52,70,95,23,04,60,11,42,69,24,68,56,01,32,56,71,37,02,36,91
        dq 22,31,16,71,51,67,63,89,41,92,36,54,22,40,40,28,66,33,13,80
        dq 24,47,32,60,99,03,45,02,44,75,33,53,78,36,84,20,35,17,12,50
        dq 32,98,81,28,64,23,67,10,26,38,40,67,59,54,70,66,18,38,64,70
        dq 67,26,20,68,02,62,12,20,95,63,94,39,63,08,40,91,66,49,94,21
        dq 24,55,58,05,66,73,99,26,97,17,78,78,96,83,14,88,34,89,63,72
        dq 21,36,23,09,75,00,76,44,20,45,35,14,00,61,33,97,34,31,33,95
        dq 78,17,53,28,22,75,31,67,15,94,03,80,04,62,16,14,09,53,56,92
        dq 16,39,05,42,96,35,31,47,55,58,88,24,00,17,54,24,36,29,85,57
        dq 86,56,00,48,35,71,89,07,05,44,44,37,44,60,21,58,51,54,17,58
        dq 19,80,81,68,05,94,47,69,28,73,92,13,86,52,17,77,04,89,55,40
        dq 04,52,08,83,97,35,99,16,07,97,57,32,16,26,26,79,33,27,98,66
        dq 88,36,68,87,57,62,20,72,03,46,33,67,46,55,12,32,63,93,53,69
        dq 04,42,16,73,38,25,39,11,24,94,72,18,08,46,29,32,40,62,76,36
        dq 20,69,36,41,72,30,23,88,34,62,99,69,82,67,59,85,74,04,36,16
        dq 20,73,35,29,78,31,90,01,74,31,49,71,48,86,81,16,23,57,05,54
        dq 01,70,54,71,83,51,54,69,16,92,33,48,61,43,52,01,89,19,67,48
    fmt db "%ld",10,0

section .text

    global main

    main:
        lea rsi, [arr]
        sub rsi, 8
        xor rbp, rbp

    loop:
        add rsi, 8
        cmp rsi, arr + 3192         ;check less than address of final number
        jnc exit

        mov rax, rsi                ;get x and y coordinates to test which directions we can check
        sub rax, arr                ;take into account arr offset
        mov rbx, 8
        xor rdx, rdx
        div rbx                     ;divide by qword length 8 to get current index of array
        mov rbx, 20
        xor rdx, rdx
        div rbx                     ;divide by 20 (grid width) to get y and x (as the remainder)
        mov r8, rax                 ;y
        mov r9, rdx                 ;x

        cmp r9, 16                  ;if x < 16
        jnc _0

        call horiz
        call check

        cmp r8, 16                  ;if y < 16
        jnc _0

        call nw_se
        call check

    _0:
        cmp r8, 16                  ;if y < 16
        jnc _1

        call vert
        call check

        cmp r9, 3                   ;if x > 3
        jc _1

        call ne_sw
        call check

    _1:
        jmp loop

    check:                          ;check product and save in rbp is bigger than current
        mov r10, rdx
        mul rbx
        mul rcx
        mul r10
        cmp rbp, rax
        cmovc rbp, rax
        ret


    horiz:                          ;load horizontal numbers into registers
        mov rax, [rsi]
        mov rbx, [rsi + 8]
        mov rcx, [rsi + 16]
        mov rdx, [rsi + 24]
        ret

    vert:                           ;load values of vertical numbers into registers
        mov rax, [rsi]
        mov rbx, [rsi + 20*8]
        mov rcx, [rsi + 40*8]
        mov rdx, [rsi + 60*8]
        ret

    nw_se:                          ;load diagonal values into registers
        mov rax, [rsi]
        mov rbx, [rsi + 19*8]
        mov rcx, [rsi + 38*8]
        mov rdx, [rsi + 57*8]
        ret

    ne_sw:                          ;load diagonal values into registers
        mov rax, [rsi]
        mov rbx, [rsi + 21*8]
        mov rcx, [rsi + 42*8]
        mov rdx, [rsi + 63*8]
        ret

    exit:
        mov rdi, fmt
        mov rsi, rbp
        mov rax, 0
        call printf

        xor rax, rax
        ret