1 /* Pausing execution of the current thread. 2 Copyright (C) 2009-2021 Free Software Foundation, Inc. 3 Written by Eric Blake <ebb9@byu.net>, 2009. 4 5 This file is free software: you can redistribute it and/or modify 6 it under the terms of the GNU Lesser General Public License as 7 published by the Free Software Foundation; either version 2.1 of the 8 License, or (at your option) any later version. 9 10 This file is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 GNU Lesser General Public License for more details. 14 15 You should have received a copy of the GNU Lesser General Public License 16 along with this program. If not, see <https://www.gnu.org/licenses/>. */ 17 18 /* This file is _intentionally_ light-weight. Rather than using 19 select or nanosleep, both of which drag in external libraries on 20 some platforms, this merely rounds up to the nearest second if 21 usleep() does not exist. If sub-second resolution is important, 22 then use a more powerful interface to begin with. */ 23 24 #include <config.h> 25 26 /* Specification. */ 27 #include <unistd.h> 28 29 #include <errno.h> 30 31 #if defined _WIN32 && ! defined __CYGWIN__ 32 # define WIN32_LEAN_AND_MEAN /* avoid including junk */ 33 # include <windows.h> 34 #endif 35 36 #ifndef HAVE_USLEEP 37 # define HAVE_USLEEP 0 38 #endif 39 40 /* Sleep for MICRO microseconds, which can be greater than 1 second. 41 Return -1 and set errno to EINVAL on range error (about 4295 42 seconds), or 0 on success. Interaction with SIGALARM is 43 unspecified. */ 44 45 int 46 usleep (useconds_t micro) /* */ 47 #undef usleep 48 { 49 #if defined _WIN32 && ! defined __CYGWIN__ 50 unsigned int milliseconds = micro / 1000; 51 if (sizeof milliseconds < sizeof micro && micro / 1000 != milliseconds) 52 { 53 errno = EINVAL; 54 return -1; 55 } 56 if (micro % 1000) 57 milliseconds++; 58 Sleep (milliseconds); 59 return 0; 60 #else 61 unsigned int seconds = micro / 1000000; 62 if (sizeof seconds < sizeof micro && micro / 1000000 != seconds) 63 { 64 errno = EINVAL; 65 return -1; 66 } 67 if (!HAVE_USLEEP && micro % 1000000) 68 seconds++; 69 while ((seconds = sleep (seconds)) != 0); 70 71 # if !HAVE_USLEEP 72 # define usleep(x) 0 73 # endif 74 return usleep (micro % 1000000); 75 #endif 76 }