FreeCalypso > hg > freecalypso-tools
view rvinterf/etmsync/interf.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
/* * In this module we implement our synchronous interface to the target * via rvinterf. */ #include <sys/types.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include "limits.h" #include "localsock.h" #include "pktmux.h" #include "exitcodes.h" extern int sock; int rx_enable_state; u_char rvi_msg[LOCALSOCK_MAX_MSG]; int rvi_msg_len; static void collect_bytes_from_rvi(buf, nbytes) u_char *buf; { int cc; while (nbytes) { cc = read(sock, buf, nbytes); if (cc <= 0) { perror("read from rvinterf socket"); exit(ERROR_RVINTERF); } buf += cc; nbytes -= cc; } } collect_rvi_msg() { u_char lenbuf[2]; collect_bytes_from_rvi(lenbuf, 2); rvi_msg_len = lenbuf[0] << 8 | lenbuf[1]; if (rvi_msg_len < 1 || rvi_msg_len > LOCALSOCK_MAX_MSG) { fprintf(stderr, "Invalid length from rvinterf: %02X%02X\n", lenbuf[0], lenbuf[1]); exit(ERROR_RVINTERF); } collect_bytes_from_rvi(rvi_msg, rvi_msg_len); return(0); } send_rvimisc_command(cmdpkt, cmdlen) u_char *cmdpkt; { u_char lenbuf[2]; lenbuf[0] = 0; lenbuf[1] = cmdlen; write(sock, lenbuf, 2); write(sock, cmdpkt, cmdlen); } rx_control(enable) { u_char cmdpkt[2]; int cmdlen; /* are we already in the desired state? */ if (rx_enable_state == enable) return(0); /* no, do the work */ if (enable) { cmdpkt[0] = CLI2RVI_WANT_MUXPROTO; cmdpkt[1] = RVT_TM_HEADER; cmdlen = 2; } else { cmdpkt[0] = CLI2RVI_RESET_PACKET_RX; cmdlen = 1; } send_rvimisc_command(cmdpkt, cmdlen); collect_rvi_msg(); if (rvi_msg[0] != RVI2CLI_LOCAL_CMD_RESP || rvi_msg_len < 2) { fprintf(stderr, "error: unexpected response to rvinterf local command\n"); exit(ERROR_RVINTERF); } if (rvi_msg[1] != '+') { fprintf(stderr, "Error from rvinterf: %.*s\n", rvi_msg_len - 1, rvi_msg + 1); exit(ERROR_RVINTERF); } rx_enable_state = enable; return(0); } send_pkt_to_target(pkt, pktlen) u_char *pkt; { u_char hdrbuf[3]; int len1; len1 = pktlen + 1; hdrbuf[0] = len1 >> 8; hdrbuf[1] = len1 & 0xFF; hdrbuf[2] = CLI2RVI_PKT_TO_TARGET; write(sock, hdrbuf, 3); write(sock, pkt, pktlen); } target_pkt_exch(outpkt, outpktlen) u_char *outpkt; { rx_control(1); send_pkt_to_target(outpkt, outpktlen); collect_rvi_msg(); if (rvi_msg[0] != RVI2CLI_PKT_FROM_TARGET) { fprintf(stderr, "error: unexpected response type from rvinterf\n"); exit(ERROR_RVINTERF); } return(0); } etm_pkt_exch(outbuf, outlen) u_char *outbuf; { int i, c; outbuf[0] = RVT_TM_HEADER; c = 0; for (i = 1; i <= outlen; i++) c ^= outbuf[i]; outbuf[i] = c; target_pkt_exch(outbuf, outlen + 2); if (rvi_msg[1] != RVT_TM_HEADER) { printf("error: packet from target is not ETM!\n"); return(ERROR_TARGET); } if (rvi_msg_len < 5) { printf("error: ETM response packet is too short\n"); return(ERROR_TARGET); } c = 0; for (i = 2; i < rvi_msg_len; i++) c ^= rvi_msg[i]; if (c) { printf("ETM response checksum error!\n"); return(ERROR_TARGET); } if (rvi_msg[2] != outbuf[1]) { printf("error: target response is from wrong ETM component\n"); return(ERROR_TARGET); } return(0); }