FreeCalypso > hg > freecalypso-tools
view loadtools/ttypassthru.c @ 407:19e5a3e2f9c0
fcup-settime: moved time() retrieval a little closer to the output
A fundamental problem with all simple time transfer tools is that there is
always some delay between the time retrieval on the source system and that
transmitted time being set on the destination, and the resulting time
on the destination system is off by that delay amount. This delay cannot
be fully eliminated when working in a simple environment like ours,
but we should make our best effort to minimize it. In the present case,
moving the atinterf_init() call before the time() retrieval should make
a teensy-tiny improvement.
author | Mychaela Falconia <falcon@freecalypso.org> |
---|---|
date | Sat, 11 Aug 2018 21:52:17 +0000 |
parents | e7502631a0f9 |
children |
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line source
/* * This module implements the pass-thru operation mode, in which * the Unix host tty is cross-connected directly to the target * running some code we have just loaded. */ #include <sys/types.h> #include <sys/ioctl.h> #include <sys/errno.h> #include <termios.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <strings.h> extern int errno; extern int target_fd; static struct termios saved_termios, my_termios; static void safe_output(buf, cc) u_char *buf; { int i, c; for (i = 0; i < cc; i++) { c = buf[i]; if (c == '\r' || c == '\n' || c == '\t' || c == '\b') { putchar(c); continue; } if (c & 0x80) { putchar('M'); putchar('-'); c &= 0x7F; } if (c < 0x20) { putchar('^'); putchar(c + '@'); } else if (c == 0x7F) { putchar('^'); putchar('?'); } else putchar(c); } fflush(stdout); } static void loop() { char buf[BUFSIZ]; fd_set fds, fds1; register int i, cc, max; FD_ZERO(&fds); FD_SET(0, &fds); FD_SET(target_fd, &fds); max = target_fd + 1; for (;;) { bcopy(&fds, &fds1, sizeof(fd_set)); i = select(max, &fds1, NULL, NULL, NULL); if (i < 0) { if (errno == EINTR) continue; tcsetattr(0, TCSAFLUSH, &saved_termios); perror("select"); exit(1); } if (FD_ISSET(0, &fds1)) { cc = read(0, buf, sizeof buf); if (cc <= 0) return; if (cc == 1 && buf[0] == 0x1C) return; write(target_fd, buf, cc); } if (FD_ISSET(target_fd, &fds1)) { cc = read(target_fd, buf, sizeof buf); if (cc <= 0) { tcsetattr(0, TCSAFLUSH, &saved_termios); fprintf(stderr, "EOF/error on target tty\n"); exit(1); } safe_output(buf, cc); } } } tty_passthru() { static int zero = 0; ioctl(target_fd, FIONBIO, &zero); tcgetattr(0, &saved_termios); bcopy(&saved_termios, &my_termios, sizeof(struct termios)); cfmakeraw(&my_termios); my_termios.c_cc[VMIN] = 1; my_termios.c_cc[VTIME] = 0; tcsetattr(0, TCSAFLUSH, &my_termios); printf("Entering tty pass-thru; type ^\\ to exit\r\n\n"); loop(); tcsetattr(0, TCSAFLUSH, &saved_termios); return 0; }