diff options
Diffstat (limited to 'serial.c')
-rw-r--r-- | serial.c | 70 |
1 files changed, 70 insertions, 0 deletions
@@ -361,3 +361,73 @@ int serialport_read(unsigned char *buf, unsigned int readcnt) return 0; } + +/* Tries up to timeout ms to read readcnt characters and places them into the array starting at c. Returns + * 0 on success, positive values on temporary errors (e.g. timeouts) and negative ones on permanent errors. + * If really_read is not NULL, this function sets its contents to the number of bytes read successfully. */ +int serialport_read_nonblock(unsigned char *c, unsigned int readcnt, unsigned int timeout, unsigned int *really_read) +{ + int ret = 1; + /* disable blocked i/o and declare platform-specific variables */ +#ifdef _WIN32 + DWORD rv; + COMMTIMEOUTS oldTimeout; + COMMTIMEOUTS newTimeout = { + .ReadIntervalTimeout = MAXDWORD, + .ReadTotalTimeoutMultiplier = 0, + .ReadTotalTimeoutConstant = 0, + .WriteTotalTimeoutMultiplier = 0, + .WriteTotalTimeoutConstant = 0 + }; + if(!GetCommTimeouts(sp_fd, &oldTimeout)) { + msg_perr_strerror("Could not get serial port timeout settings: "); + return -1; + } + if(!SetCommTimeouts(sp_fd, &newTimeout)) { +#else + ssize_t rv; + const int flags = fcntl(sp_fd, F_GETFL); + if (fcntl(sp_fd, F_SETFL, flags | O_NONBLOCK) != 0) { +#endif + msg_perr_strerror("Could not set serial port timeout settings %s"); + return -1; + } + + int i; + int rd_bytes = 0; + for (i = 0; i < timeout; i++) { + msg_pspew("readcnt %d rd_bytes %d\n", readcnt, rd_bytes); +#ifdef _WIN32 + ReadFile(sp_fd, c + rd_bytes, readcnt - rd_bytes, &rv, NULL); + msg_pspew("read %lu bytes\n", rv); +#else + rv = read(sp_fd, c + rd_bytes, readcnt - rd_bytes); + msg_pspew("read %zd bytes\n", rv); +#endif + if ((rv == -1) && (errno != EAGAIN)) { + msg_perr_strerror("Serial port read error: "); + ret = -1; + break; + } + if (rv > 0) + rd_bytes += rv; + if (rd_bytes == readcnt) { + ret = 0; + break; + } + internal_delay(1000); /* 1ms units */ + } + if (really_read != NULL) + *really_read = rd_bytes; + + /* restore original blocking behavior */ +#ifdef _WIN32 + if (!SetCommTimeouts(sp_fd, &oldTimeout)) { +#else + if (fcntl(sp_fd, F_SETFL, flags) != 0) { +#endif + msg_perr_strerror("Could not restore serial port timeout settings: %s\n"); + ret = -1; + } + return ret; +} |