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@qRoC qRoC/main.cpp
Last active Feb 19, 2018

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GO compiler
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <float.h>
#include <sys/time.h>
#include <stdint.h>
typedef int64_t TimeVal;
TimeVal getPerfTime()
{
timeval now;
gettimeofday(&now, 0);
return (TimeVal)now.tv_sec*1000000L + (TimeVal)now.tv_usec;
}
int getPerfDeltaTimeUsec(const TimeVal start, const TimeVal end)
{
return (int)(end - start);
}
float InvSqrt(float x)
{
float xhalf = 0.5f*x;
int i = *(int *)&x;
i = 0x5f3759df - (i >> 1);
x = *(float *)&i;
x = x*(1.5f - xhalf*x*x);
return x;
}
int main(int argc, char *argv[])
{
TimeVal timeStart = getPerfTime();
double res = 0.0;
for (int z = 0; z < 10000000; ++z)
{
res += InvSqrt(double(4121214.151244124125));
}
TimeVal timeEnd = getPerfTime();
printf("%f # %.3fms\n", res, getPerfDeltaTimeUsec(timeStart, timeEnd) / 1000.0);
return 0;
}
package main
import (
"fmt"
"time"
"math"
)
func InvSqrt(x float32) float32 {
xhalf := 0.5 * x
i := math.Float32bits(x)
i = 0x5f3759df - (i >> 1)
x = math.Float32frombits(i)
x = x * (1.5 - xhalf * x * x)
return x
}
func main() {
time_start := time.Now()
var res float64
for z := 0; z < 10000000; z++ {
res += float64(InvSqrt(4121214.151244124125))
}
fmt.Print(res)
fmt.Print(" # ")
fmt.Println(time.Now().Sub(time_start));
}
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <float.h>
#include <sys/time.h>
#include <stdint.h>
typedef int64_t TimeVal;
TimeVal getPerfTime()
{
timeval now;
gettimeofday(&now, 0);
return (TimeVal)now.tv_sec*1000000L + (TimeVal)now.tv_usec;
}
int getPerfDeltaTimeUsec(const TimeVal start, const TimeVal end)
{
return (int)(end - start);
}
float InvSqrt(float x)
{
return 1.0 / sqrtf(x);
}
int main(int argc, char *argv[])
{
TimeVal timeStart = getPerfTime();
double res = 0.0;
for (int z = 0; z < 10000000; ++z)
{
res += InvSqrt(4121214.151244124125);
}
TimeVal timeEnd = getPerfTime();
printf("%f # %.3fms\n", res, getPerfDeltaTimeUsec(timeStart, timeEnd) / 1000.0);
return 0;
}
package main
import (
"fmt"
"time"
)
//go:noescape
func Sqrt(x float32) float32 // ./main2_$GOARCH.s
func InvSqrt(x float32) float32 {
return float32(1.0 / Sqrt(x))
}
func main() {
time_start := time.Now()
var res float64
for z := 0; z < 10000000; z++ {
res += float64(InvSqrt(4121214.151244124125))
}
fmt.Print(res)
fmt.Print(" # ")
fmt.Println(time.Now().Sub(time_start));
}
// func Sqrt(x float32) float32
TEXT ·Sqrt+0(SB),$0-16
SQRTSS x+0(FP), X0
MOVSS X0,r+8(FP)
RET
v1
4917.670739814639 # 24.788318ms
v2
4925.920511595905 # 50.62856ms
v3
4917.670740 # 8.815ms
v4
4925.920512 # 12.797ms
#!/bin/sh
cd main1; go build -o "v1"; cd ..
cd main2; go build -o "v2"; cd ..
g++ -O3 -o v3 main.cpp
g++ -O3 -o v4 main2.cpp
echo
echo "v1"
./main1/v1
echo
echo "v2"
./main2/v2
echo
echo "v3"
./v3
echo
echo "v4"
./v4
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