TITLE PASS 8 QUADRATIC FORMULA                      (main.asm)

; Description:
; Caluculates the elapsed time over perfomring the quadratic formula 1000000 times

INCLUDE Irvine32.inc
.data
;-----------------------
;messages & prompts
;----------------------
myMessage       BYTE    "Rhett Newton's Quadratic Formula Solver",0dh,0ah,0
explanation     BYTE    "Solve x^2-3x-4 with quadratic formula using FPU",0dh,0ah,0
coef_a_prompt   BYTE    "Enter coefficient a",0dh,0ah,0
coef_b_prompt   BYTE    "Enter coefficient b",0dh,0ah,0
coef_c_prompt   BYTE    "Enter coefficient c",0dh,0ah,0
realRoots       BYTE    "Real Roots    :",0dh,0ah,0
timeMessage     BYTE    "Computational time: ", 0

;----------------------
;variables
;----------------------
startTime   DWORD   ?
endTime     DWORD   ?
coef_a      BYTE    ?
coef_b      BYTE    ?
coef_c      BYTE    ?
root1       DWORD   ?
root2       DWORD   ?
dbl1        REAL4   ?
dbl2        REAL4   ?

;----------------------
;prototypes
;----------------------
displayMessage  PROTO, string:PTR BYTE
quadFormula     PROTO, num:DWORD
.code
main PROC
    call    Clrscr
    finit
    invoke  displayMessage, OFFSET myMessage    ;displaying welcome message
    invoke  displayMessage, OFFSET explanation  ;displaying explanation

    ;--------------------------------
    ;getting coefficents
    ;--------------------------------
    call    getCoefficients                     ;calling getCoefficients procedure

    ;------------------------------------------
    ;performing the quadratic formula x times
    ;------------------------------------------
    invoke  quadFormula, 1000000                ;invoking quadFormula

    ;------------------------------------------
    ;displaying real roots
    ;------------------------------------------
    call    displayRoots                        ;calling display roots

    ;-------------------------------
    ;Displaying Benchmark stats
    ;-------------------------------
    ;calculate ending time here**********
    invoke  displayMessage, OFFSET timeMessage ;displaying timeMessage
    call    WriteDec                           ;displaying elapsedTime
    nop
    exit
main ENDP

;--------------------------------------
quadFormula PROC num:DWORD
;Performs the quadratic formula x
;amount of times.
;params: num: the number of times to
;               perform the operation
;--------------------------------------
    mov     ecx, num        ;moving num to the ecx register
    ;-------------------------------
    ;getting the starting time
    ;-------------------------------
    call    GetTickCount    ;getting the current time
    mov     startTime, eax  ;storing starting time

L1:
    ;the meat of the program is here
    ;-----------------------------------------------------
    ;getting 2 * a
    finit
    mov     eax, 2
    mul     coef_a
    mov     dbl2, eax
    fld     dbl2            ;2*a is stored in st(0)
    ;getting -4*a*c
    movzx   eax, coef_a
    mul     coef_c
    mov     bl, -4
    mul     bl
    ;storing in ebx
    mov     ebx, eax
    ;getting b^2
    movzx   eax, coef_b
    mul     eax
    ;getting b^2-4*a*c
    sub     eax, ebx
    mov     dbl1, eax
    fld     dbl1            ;storing b^2-4*a*c in st(0), st(1) = 2 * a
    ;getting sqrt(b^2-4*a*c)
    fsqrt
    ;dividing by 2 * a
    fdiv    st(0), st(2)
    fld     st(0)           ;now st(0) = st(1) = sqrt(b^2-4*a*c)/2*a
    movzx   ebx, coef_b
    neg     ebx
    mov     dbl1, ebx
    fld     dbl1
    fsub    st(2), st       ;subtract value of st(0) from st(2), store in st(2)
    fadd    st(1), st       ;add value of st(0) to st(1), store in st(1)
    ;-----------------------------------------------------
    dec     ecx             ;decrementing the ecx register
    test    ecx, ecx        ;testing if ecx is zero
    jnz     L1              ;if not zero, repeat loop

    fld     st(2)           ;getting -b - sqrt(b^2-4*a*c)/2*a into st(0)
    fld     st(2)           ;getting -b + sqrt(b^2-4*a*c)/2*a into st(0) //-b - sqrt(b^2-4*a*c)/2*a st(1)
    ;-------------------------------
    ;getting the ending time
    ;-------------------------------
    call    GetTickCount    ;getting the ending time
    mov     endTime, eax    ;calculating the elapsed time

    ret
quadFormula ENDP

;------------------------------------
displayRoots PROC
;displays the numbers stored in st(0) and st(1)
;------------------------------------
    invoke  displayMessage, OFFSET realRoots
    call    WriteFloat
    call    crlf
    fld     st(1)
    call    WriteFloat
    call    crlf
    ret
displayRoots ENDP

;-------------------------------------
getCoefficients PROC
;prompts the user for the coefficents
;to use in the quadratic formula.
;stores them in their respective variables
;-------------------------------------
    ;getting coefficent a
    invoke  displayMessage, OFFSET coef_a_prompt    ;displaying coef_a_prompt
    call    readInt                                 ;getting input from user
    mov     coef_a, al                              ;storing input to variable

    ;getting coefficent b
    invoke  displayMessage, OFFSET coef_b_prompt    ;displaying coef_b_prompt
    call    readInt                                 ;getting input from user
    mov     coef_b, al                              ;storing input to variable

    ;getting coefficent c
    invoke  displayMessage, OFFSET coef_c_prompt    ;displaying coef_c_prompt
    call    readInt                                 ;getting input from user
    mov     coef_c, al                              ;storing input to variable

    ret
getCoefficients ENDP

;------------------------------------
displayMessage PROC string:PTR BYTE
;Displays a message to the user
;params: string: a ptr to a byte array
;------------------------------------
    mov     edx, string     ;moves ptr to edx register
    call    WriteString     ;displays string
    ret
displayMessage ENDP
END main