/**
 * COSC 221: Lab 4 - Calculate Date of Easter
 * Author:   Gilbert Fulmore
 * Date:     2015/02/16
 */
define(c_r, l0)
define(y_r, l1)
define(m_r, l2)
define(d_r, l3)
define(g_r, l4)
define(x_r, l5)
define(z_r, l6)
define(e_r, l7)
define(n_r, l8)

    .global main
main:               !int main() {
    save   %sp, -96, %sp        !int c; //century
                        !int y; //year
                    !int m; //month
                    !int d; //day

                    !int g; //golden number
                    !int x; //number of dropped leap years
                    !int z; //synchronize easter with moon orbit
                    !int e; //epact
                    !int n; //find full moon

                    !printf("Enter Year: ");
    mov    1984, %y_r       !scanf("%d", &y);

                    !//find golden number
    mov    %y_r, %o0        !g = (y % 19) + 1;
    mov    19, %o1
    call   .rem
    nop
    add    %o0, 1, %g_r
                    !//find century
    mov    %y_r, %o0        !c = (y / 100) + 1;
    mov    100, %o1
    call   .div
    nop
    add    %o0, 1, %c_r

    mov    %y_r, %o0        !if (y % 100 != 0) {
    mov    100, %o1
    call   .rem
    nop
        cmp    %o0, %g0
    be     done
    nop

    mov    3, %o0               !x = (3 * c / 4) - 12;
    mov    %c_r, %o1
    call   .mul
        nop
        mov    4, %o1
        call   .div
        nop
        sub    %o0, 12, %x_r

    mov    8, %o0               !z = ((8 * c + 5) / 25) - 5;
    mov    %c_r, %o1
    call   .mul
    nop
    add    %o0, 5, %o0
    mov    25, %o1
    call   .div
    nop
        sub    %o0, 5, %z_r
done:                   !}

                    !//find sunday
    mov    5, %o0           !d = (5 * y / 4) - x - 10;
    mov    %y_r, %o1
    call   .mul
    nop
    mov    4, %o1
    call   .div
    nop
    sub    %o0, %x_r, %o0
        sub    %o0, 10, %d_r
                    !//find the "epact" E
    mov    11, %o0          !e = (11 * g + 20 + z - x) % 30;
    mov    %g_r, %o1
    call   .mul
    nop
    add    %o0, 20, %o0
    add    %o0, %z_r, %o0
    sub    %o0, %x_r, %o0
    mov    30, %o1
    call   .rem
    nop
    mov    %o0, %e_r
                    !if (e == 25 && g > 11 || e == 24)
    subcc  %e_r, 25, %o0        !if (e == 25)
    bne    done
    nop
    subcc  %g_r, 11, %o1        !if (g > 11)
    bl     done
    nop
    and    %o0, %o1, %o0        !if ((e == 25) && (g > 11))
    subcc  %e_r, 24, %o1        !if (e == 24)
    bne    done
    nop
    or     %o0, %o1, %o0        !if ((e == 25 && g > 11) || (e == 24))
    cmp    %o0, 1           !if (true)
    bne    done
    nop

    add    %e_r, 1, %e_r                !++e;
done:
                    !//find full moon
    sub    44, %e_r, %n_r       !n = 44 - e;

    cmp    %n_r, 21         !if (n < 21)
    bg     done
    nop
    add    %n_r, 30, %n_r           !n += 30;
done:
                    !//advance to sunday
    add    %d_r, %n_r, %o0      !n = n + 7 - ((d + n) % 7);
    mov    7, %o1
    call   .rem
    nop
    add    %n_r, 7, %n_r
    sub    %n_r, %o0, %n_r
                    !//get month
    cmp    %n_r, 31         !if (n > 31) {
    bl     else
    nop
    mov    4, %m_r              !m = 4;
    sub    %n_r, 31, %d_r           !d = n-31;
    ba     done
    nop
else:                   !} else {
                        !m = 3;
                        !d = n;
done:                   !}

                    !printf("Easter date: %d-%d-%d\n", y, m, d);
    mov    1, %g1           !return 0;
    ta     0
                !}