dahdi_tools 分析（三）dahdi_testdahdi_tools 分析（三）dahdi_test

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dahdi_tools 分析（三）dahdi_test

dahdi_test 的使用

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# dahdi_test -h
Usage: dahdi_test [-c COUNT] [-v]
Valid options are:
-c COUNT
Run just COUNT cycles (otherwise: forever).
-v
More verbose output.
-h
This help text.

示例：

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# dahdi_test 
Opened pseudo dahdi interface, measuring accuracy...
97.888% 97.881% 97.891% 97.884% 97.883% 97.878% 97.895% 97.884%
97.878% ^C
--- Results after 9 passes ---
Best: 97.895% -- Worst: 97.878% -- Average: 97.884602%
Cummulative Accuracy (not per pass): 97.885

代码分析

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static double calculate_accuracy(double count, double ms)
{
return ((count - _fmin(count, fabs(count - ms))) / count) * 100.0;
}
int main(int argc, char *argv[])
{
int fd;
int res;
int c;
int count = 0;
int seconds = 0;
int curarg = 1;
char buf[8192];
float ms;
struct timeval start, now;
fd = open("/dev/dahdi/pseudo", O_RDWR);
// 打开/dev/dahdi/pseudo
if (fd < 0) {
fprintf(stderr, "Unable to open dahdi interface: %sn", strerror(errno));
exit(1);
}
for (;;) {
if (count == 0)
ms = 0;
gettimeofday(&start, NULL);
// 计时开始
res = read(fd, buf, sizeof(buf));
// 读取 8192 字节数据
if (res < 0) {
fprintf(stderr, "Failed to read from pseudo interface: %sn", strerror(errno));
exit(1);
}
count += res;
gettimeofday(&now, NULL);
// 计时结束
ms += (now.tv_sec - start.tv_sec) * 8000;
ms += (now.tv_usec - start.tv_usec) / 125.0;
if (count >= SIZE) {
const double percent = calculate_accuracy(count, ms);
if (verbose) {
printf("n%d samples in %0.3f system clock sample intervals (%.3f%%)",
count, ms, percent);
} else if (pass > 0 && (pass % 8) == 0) {
printf("n");
}
if (percent > best)
best = percent;
if (percent < worst)
worst = percent;
if (!verbose)
printf("%.3f%% ", percent);
total += percent;
fflush(stdout);
total_count += count;
total_time += ms;
count = 0;
pass++;
}
}

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static double calculate_accuracy(double count, double ms)
{
return ((count - _fmin(count, fabs(count - ms))) / count) * 100.0;
}
int main(int argc, char *argv[])
{
int fd;
int res;
int c;
int count = 0;
int seconds = 0;
int curarg = 1;
char buf[8192];
float ms;
struct timeval start, now;
fd = open("/dev/dahdi/pseudo", O_RDWR);
// 打开/dev/dahdi/pseudo
if (fd < 0) {
fprintf(stderr, "Unable to open dahdi interface: %sn", strerror(errno));
exit(1);
}
for (;;) {
if (count == 0)
ms = 0;
gettimeofday(&start, NULL);
// 计时开始
res = read(fd, buf, sizeof(buf));
// 读取 8192 字节数据
if (res < 0) {
fprintf(stderr, "Failed to read from pseudo interface: %sn", strerror(errno));
exit(1);
}
count += res;
gettimeofday(&now, NULL);
// 计时结束
ms += (now.tv_sec - start.tv_sec) * 8000;
ms += (now.tv_usec - start.tv_usec) / 125.0;
if (count >= SIZE) {
const double percent = calculate_accuracy(count, ms);
if (verbose) {
printf("n%d samples in %0.3f system clock sample intervals (%.3f%%)",
count, ms, percent);
} else if (pass > 0 && (pass % 8) == 0) {
printf("n");
}
if (percent > best)
best = percent;
if (percent < worst)
worst = percent;
if (!verbose)
printf("%.3f%% ", percent);
total += percent;
fflush(stdout);
total_count += count;
total_time += ms;
count = 0;
pass++;
}
}