main.cpp

#include "stdio.h"

extern "C" double CalcSum(float a, double b, float c, double d, float e, double f);
extern "C" double CalcDist(int x1, double x2, long long y1, double y2, float z1, short z2);

void CalcSumCpp(void)
{
    float a = 10.0f;
    double b = 20.0;
    float c = 0.5f;
    double d = 0.0625;
    float e = 15.0f;
    double f = 0.125;

    double sum = CalcSum(a, b, c, d, e, f);

    printf("\nResults for CalcSum()\n");
    printf("a: %10.4f  b: %10.4lf c: %10.4f\n", a, b, c);
    printf("d: %10.4lf  e: %10.4f f: %10.4lf\n", d, e, f);
    printf("\nsum: %10.4lf\n", sum);
}

void CalcDistCpp(void)
{
    int x1 = 5;
    double x2 = 12.875;
    long long y1 = 17;
    double y2 = 23.1875;
    float z1 = -2.0625;
    short z2 = -6;

    double dist = CalcDist(x1, x2, y1, y2, z1, z2);

    printf("\nResults for CalcDist()\n");
    printf("x1: %10d  x2: %10.4lf\n", x1, x2);
    printf("y1: %10lld  y2: %10.4lf\n", y1, y2);
    printf("z1: %10.4f  z2: %10d\n", z1, z2);
    printf("\ndist: %12.6lf\n", dist);
}

int main(int argc, char* argv[])
{
    CalcSumCpp();
    CalcDistCpp();
    return 0;
}

floatingpointarithmetic.asm

; Name:         floatingpointarithmetic.asm
;
; Build:        g++ -c main.cpp -o main.o
;               nasm -f elf64 -o floatingpointarithmetic.o floatingpointarithmetic.asm
;               g++ -o floatingpointarithmetic floatingpointarithmetic.o main.o
;
; Source:       Modern x86 Assembly Language Programming p.519

global CalcSum
global CalcDist

section .text

; extern "C" double CalcSum(float a, double b, float c, double d, float e, double f);
;
; Description:  The following function demonstrates how to access
;               floating-point argument values in an x86-64 function.

CalcSum:
    ; registers: xmm0 = a
    ;            xmm1 = b
    ;            xmm2 = c
    ;            xmm3 = d
    ;            xmm4 = e
    ;            xmm5 = f
    ; Sum the argument values
    cvtss2sd xmm0,xmm0                  ;promote a to DPFP
    addsd    xmm0,xmm1                  ;xmm0 = a + b
    cvtss2sd xmm2,xmm2                  ;promote c to DPFP
    addsd    xmm0,xmm2                  ;xmm0 = a + b + c
    addsd    xmm0,xmm3                  ;xmm0 = a + b + c + d
    cvtss2sd xmm4,xmm4                  ;promote e to DPFP
    addsd    xmm0,xmm4                  ;xmm0 = a + b + c + d + e
    addsd    xmm0,xmm5                  ;xmm0 =  a + b + c + d + e + f
    ret

; extern "C" double CalcDist(int x1, double x2, long long y1, double y2, float z1, short z2);
;
; Description:  The following function demonstrates how to access mixed
;               floating-point and integer arguments values in an
;               x86-64 function.

CalcDist:
    ; registers: edi  = x1
    ;            xmm0 = x2
    ;            rsi  = y1
    ;            xmm1 = y2
    ;            xmm2 = z1
    ;            dl   = z2  (in reality z2 is stored in edx)
    ; Calculate xd = (x2 - x1) * (x2 - x1)
    cvtsi2sd xmm3,edi                      ;convert x1 to DPFP
    subsd    xmm0,xmm3                     ;xmm0 = x2 - x1
    mulsd    xmm0,xmm0                     ;xmm0 = xd

    ; Calculate yd = (y2 - y1) * (y2 - y1)
    cvtsi2sd xmm4,rsi                      ;convert y1 to DPFP
    subsd    xmm1,xmm4                     ;xmm1 = y2 - y1
    mulsd    xmm1,xmm1                     ;xmm1 = yd

    ; Calculate zd = (z2 - z1) * (z2 - z1)
    ;movss xmm0,real4 ptr [rsp+40]         ;xmm=0  = z1
    cvtss2sd xmm3,xmm2                     ;convert z1 to DPFP
    movsx    eax,dl                        ;eax = sign-extend z2
    cvtsi2sd xmm2,eax                      ;convert z2 to DPFP
    subsd    xmm2,xmm3                     ;xmm2 = z2 - z1
    mulsd    xmm2,xmm2                     ;xmm2 = zd

    ; Calculate final distance sqrt(xd + yd + zd)
    addsd    xmm0,xmm1                     ;xmm0 = xd + yd
    addsd    xmm0,xmm2                     ;xmm0 = xd + yd + zd
    sqrtsd   xmm0,xmm0                     ;xmm0 = sqrt(xd + yd + zd)
    ret

build

g++ -c main.cpp -o main.o
nasm -f elf64 -o floatingpointarithmetic.o floatingpointarithmetic.asm
g++ -o floatingpointarithmetic floatingpointarithmetic.o main.o