Question

One way to calculate the harmonic mean of two numbers x and y is using the expression (2xy) / (x + y) Using the windows32 framework, write a complete 80x86 assembly language program to prompt for and input two numbers and then calculate and display their harmonic mean in ddd.d format.

ASSEMBLY LANGUAGE
WINDOWS 32 FRAMEWORK

Answer 1

//Harmonic mean of two numbers x,y is given as 2xy/(x+y) so the basic basic approch for solving in assembly language code is //to calculate the numerator and denominator

//The ASSEMBLY CODE goes as follows

;Assembly function that computes the harmonic mean
;of an array of 64-bit floating-point numbers in 32 framework
;Retrieves input using a C program.
;
;Harmonic mean is defined as Sum(n/((1/x1) + (1/x2) + ... + (1/xn)))
;
;   expects:
;       RDI - address of array
;       RSI - length of the array
;   returns
;       XMMO - the harmonic average of array's values

global harmonicMean

section .data
    Zero dd 0.0
    One dd 1.0

section .text
    harmonicMean:
        push rbp
        mov rbp, rsp              ;C prologue

        movss xmm10, [Zero]       ;Holds tally of denominator
        cvtsi2ss xmm0, rsi        ;Take length and put it into xmm0 register

        .whileLoop:
            cmp rsi, 0            ;Is the length of array 0?
            je .endwhile
            call addDen           ;Compute a denominator value and add it to sum
            add rdi, 4            ;Add size of float to address
            dec rsi               ;Decrease the length
            jmp .whileLoop
        .endwhile:

        divss xmm0, xmm10

        leave
        ret


    ;Calculates a number in the denominator
    addDen:
        push rdi
        movss xmm8, [One]
        movss xmm9, [rdi]
        divss xmm8, xmm9
        addss xmm10, xmm8
        pop rdi
        ret