main.cpp

#include <stdio.h>

extern "C" int CalcArraySquares(int* y, const int* x, int n);

int CalcArraySquaresCpp(int* y, const int* x, int n)
{
	int sum = 0;
	
	for (int i = 0; i < n; i++)
	{
		y[i] =  x[i] * x[i];
		sum += y[i];
	}
	
	return sum;
}

int main(int argc, char* argv[])
{
	int x[] = {2, 3, 5, 7, 11, 13, 17, 19, 23, 29};
	const int n = sizeof(x) / sizeof(int);
	int y1[n];
	int y2[n];
	int sum_y1 = CalcArraySquaresCpp(y1, x, n);
	int sum_y2 = CalcArraySquares(y2, x, n);
	
	for (int i = 0; i < n; i++)
		printf("i: %2d  x: %4d  y1: %4d  y2: %4d\n", i, x[i], y1[i], y2[i]);
	printf("\n");
	
	printf("sum_y1: %d\n", sum_y1);
	printf("sum_y2: %d\n", sum_y2);
	
	return 0;
}

calcarraysquares.asm

; Name:     calcarraysquares.asm
;
; Build:    g++ -m32 -c main.cpp -o main.o
;           nasm -f elf32 -o calcarraysquares.o calcarraysquares.asm
;           g++ -m32 -o calcarraysquares calcarraysquares.o main.o
;
; Source:   Modern x86 Assembly Language Programming p.56

global  CalcArraySquares

section .text

; extern "C" int CalcArraySquares(int* y, const int* x, int n);
;
; Description:   This function cComputes y[i] = x[i] * x[i].
;
; Returns:      Sum of the elements in array y.

%define y    [ebp+8]
%define x    [ebp+12]
%define n    [ebp+16]
    
CalcArraySquares:
    push    ebp
    mov     ebp,esp
    push    ebx
    push    esi
    push    edi
    ; Load arguments
    mov     edi,y                ;edi = 'y'
    mov     esi,x                ;esi = 'x'
    mov     ecx,n                ;ecx = 'n'
    ; Initialize array sum register, calculate size of array in bytes,
    ; and initialize element offset register.
    xor     eax,eax              ;eax = sum of 'y' array
    cmp     ecx,0
    jle     .emptyArray
    shl     ecx,2                ;ecx = size of array in bytes
    xor     ebx,ebx              ;ebx = array element offset
    ; Repeat loop until finished
.l1:
    mov     edx,[esi+ebx]        ;load next x[i]
    imul    edx,edx              ;compute x[i] * x[i]
    mov     [edi+ebx],edx        ;save result to y[i]
    add     eax,edx              ;update running sum
    add     ebx,4                ;update array element offset
    cmp     ebx,ecx
    jl      .l1                  ;jump if not finished
.emptyArray:
    pop     edi
    pop     esi
    pop     ebx
    pop     ebp
    ret

build

g++ -m32 -c main.cpp -o main.o
nasm -f elf32 -o calcarraysquares.o calcarraysquares.asm
g++ -m32 -o calcarraysquares calcarraysquares.o main.o