snprintf/strncpy/strlcpy速度测试

速度测试代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/time.h>
#include <sched.h>
#define COUNT 10000000
//#define COUNT 10000000
#define MILLION 1000000L

size_t VisCore_Strlcpy(char *dst, const char *src, size_t n)
{
    const char *src0 = src;
    char dummy[];

    if (!n) {
        dst = dummy;
    }
    else {
        --n;
    }   

    while ((*dst = *src) != ) {
        if (n) {
            --n;
            ++dst;
        }
        ++src;
    }

    return src - src0;
} 

int main(void)
{
    int i;
    long long   tdif;
    struct timeval tend, tstart;
    char data[];
    char *buf1 = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
        "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
        "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaababbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb"
        "aaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb"
        "ccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc";

    char *buf = "aaaaaaaaaaaaaaaaaaaaaaaa";

    if (gettimeofday(&tstart, NULL) == -) {
        fprintf(stderr, "Failed to get start time\n");
        return ;
    }
#if 1
    for (i = ; i < COUNT; i++) {
        //snprintf(data, sizeof(data), "%s", buf);
        //snprintf(data, sizeof(data), "%s", buf);
        //strlcpy(data, buf, sizeof(data));
        VisCore_Strlcpy(data, buf, sizeof(data));
        //strncpy(data, buf, sizeof(data));
    }
#endif
    if (gettimeofday(&tend, NULL) == -) {
        fprintf(stderr, "Failed to get end time\n");
        return ;
    }
    tdif = MILLION * (tend.tv_sec - tstart.tv_sec) + (tend.tv_usec - tstart.tv_usec);
    //printf("nanosleep() time is %lld us\n", tdif);
        printf("nanosleep() time is %f us\n", tdif*1.0/COUNT);
    //printf("nanosleep() time is %lld us\n", tdif/COUNT);
    return ;
}

在hi3520a中的测试速度结果：

源、目标长度大小 相关函数	dst:24  src:678	dst:680  src:678	dst:1024  src:678	dst:1024  src:24
strncpy(us)          O2 优化	0.037871	2.408301	3.155248	2.264491
snprintf(us)         O2 优化	3.061944	3.320676	3.311918	1.46123
strlcpy(us)          O2 优化	3.681469	3.681542	3.681374	0.174848
VisCore_Strlcpy(us)  O2 优化	2.934305	2.571704	2.57172	0.108673

源、目标长度大小 相关函数	dst:24  src:678	dst:680  src:678	dst:1024  src:678	dst:1024  src:24
strncpy(us)          O2 优化	0.037871	2.408301	3.155248	2.264491
snprintf(us)         O2 优化	3.061944	3.320676	3.311918	1.46123
strlcpy(us)          O2 优化	3.681469	3.681542	3.681374	0.174848
VisCore_Strlcpy(us)  O2 优化	2.934305	2.571704	2.57172	0.108673
strlcpy(us)          Os 优化	3.684127	3.684136	3.68421	0.165779
VisCore_Strlcpy(us)  Os 优化	3.678672	3.678688	3.678671	0.185096
VisCore_Strlcpy(us)  O0 默认	16.902501	18.300108	18.302474	0.710118

参考博文：

[原创]snprintf与strncpy效率对比

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