kopia lustrzana https://github.com/pabr/leansdr
108 wiersze
3.1 KiB
C++
108 wiersze
3.1 KiB
C++
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <unistd.h>
|
|
#include <errno.h>
|
|
#include <sys/time.h>
|
|
#include <fcntl.h>
|
|
#include <string.h>
|
|
|
|
void fatal(const char *s) { perror(s); exit(1); }
|
|
|
|
void usage(const char *name, FILE *f, int c) {
|
|
fprintf(f, "Usage: %s [options]\n", name);
|
|
fprintf(f,
|
|
"Forward from stdin to stdout at constant rate.\n"
|
|
"\nOptions:\n"
|
|
" --block Pause when stdout is busy (default: '#' on stderr)\n"
|
|
" --nonblock Silently ignore when stdout is busy\n"
|
|
" --cbr R Set rate in bits per second\n"
|
|
" --cbr8 R Set rate in bytes per second\n"
|
|
" --cbr16 R Set rate in 16-bit words per second\n"
|
|
" --cbr32 R Set rate in 32-bit words per second\n"
|
|
" --cbr64 R Set rate in 64-bit words per second\n"
|
|
" -h Display this help message and exit\n"
|
|
);
|
|
exit(c);
|
|
}
|
|
|
|
int main(int argc, const char *argv[]) {
|
|
bool block=false, nonblock=false;
|
|
int bytespersec = 2400000 * 2;
|
|
|
|
for ( int i=1; i<argc; ++i ) {
|
|
if ( ! strcmp(argv[i], "-h") )
|
|
usage(argv[0], stdout, 0);
|
|
else if ( ! strcmp(argv[i], "--block") )
|
|
block = true;
|
|
else if ( ! strcmp(argv[i], "--nonblock") )
|
|
nonblock = true;
|
|
else if ( ! strcmp(argv[i], "--cbr") && i+1<argc )
|
|
bytespersec = atoll(argv[++i]) / 8;
|
|
else if ( ! strcmp(argv[i], "--cbr8") && i+1<argc )
|
|
bytespersec = atoll(argv[++i]);
|
|
else if ( ! strcmp(argv[i], "--cbr16") && i+1<argc )
|
|
bytespersec = atoll(argv[++i]) * 2;
|
|
else if ( ! strcmp(argv[i], "--cbr32") && i+1<argc )
|
|
bytespersec = atoll(argv[++i]) * 4;
|
|
else if ( ! strcmp(argv[i], "--cbr64") && i+1<argc )
|
|
bytespersec = atoll(argv[++i]) * 8;
|
|
else
|
|
usage(argv[0], stderr, 1);
|
|
}
|
|
|
|
size_t blocksize = 4096;
|
|
|
|
if ( bytespersec < blocksize )
|
|
blocksize = bytespersec;
|
|
|
|
if ( ! block ) {
|
|
long flags = fcntl(1, F_GETFL);
|
|
flags |= O_NONBLOCK;
|
|
if ( fcntl(1, F_SETFL, flags) ) fatal("fcntl(F_SETFL)");
|
|
}
|
|
|
|
struct timeval tv0;
|
|
if ( gettimeofday(&tv0, NULL) ) fatal("gettimeofday");
|
|
|
|
unsigned long long current = 0;
|
|
|
|
while ( 1 ) {
|
|
struct timeval tv;
|
|
if ( gettimeofday(&tv, NULL) ) fatal("gettimeofday");
|
|
unsigned long long reltime =
|
|
(tv.tv_sec -tv0.tv_sec )*1000000LL +
|
|
(tv.tv_usec-tv0.tv_usec);
|
|
unsigned long long target = reltime * bytespersec / 1000000;
|
|
unsigned long long want = target - current;
|
|
if ( want < blocksize ) {
|
|
long long us = blocksize * 1000000LL / bytespersec;
|
|
if ( us > 1000000 ) us = 1000000;
|
|
usleep(us);
|
|
} else {
|
|
want = blocksize;
|
|
unsigned char buf[want];
|
|
ssize_t nr = read(0, buf, want);
|
|
if ( nr < 0 ) fatal("read");
|
|
if ( ! nr ) return 0;
|
|
current += nr;
|
|
for ( unsigned char *p=buf; nr; ) {
|
|
ssize_t nw = write(1, p, nr);
|
|
if ( nw < 0 ) {
|
|
if ( errno == EWOULDBLOCK ) {
|
|
if ( ! nonblock ) fprintf(stderr, "#");
|
|
nr = 0;
|
|
} else
|
|
fatal("write");
|
|
} else if ( ! nw ) fatal("write: EOF");
|
|
else {
|
|
// Try again. If stdout is really busy we will get
|
|
// EWOULDBLOCK eventually, unless --block was set.
|
|
p += nw;
|
|
nr -= nw;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
}
|