1 files changed, 51 insertions, 0 deletions
diff --git a/m4/usleep.m4 b/m4/usleep.m4
new file mode 100644
index 0000000..d904224
--- /dev/null
+++ b/m4/usleep.m4
@@ -0,0 +1,51 @@
+# usleep.m4 serial 8
+dnl Copyright (C) 2009-2023 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+dnl This macro intentionally does not check for select or nanosleep;
+dnl both of those modules can require external libraries.
+AC_DEFUN([gl_FUNC_USLEEP],
+[
+  AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
+  dnl usleep was required in POSIX 2001, but dropped as obsolete in
+  dnl POSIX 2008; therefore, it is not always exposed in headers.
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CHECK_FUNCS_ONCE([usleep])
+  AC_CHECK_TYPE([useconds_t], [],
+    [AC_DEFINE([useconds_t], [unsigned int], [Define to an unsigned 32-bit
+      type if <sys/types.h> lacks this type.])])
+  if test $ac_cv_func_usleep = no; then
+    HAVE_USLEEP=0
+  else
+    dnl POSIX allows implementations to reject arguments larger than
+    dnl 999999, but GNU guarantees it will work.
+    AC_CACHE_CHECK([whether usleep allows large arguments],
+      [gl_cv_func_usleep_works],
+      [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
+#include <unistd.h>
+]], [[return !!usleep (1000000);]])],
+        [gl_cv_func_usleep_works=yes], [gl_cv_func_usleep_works=no],
+        [case "$host_os" in
+                          # Guess yes on glibc systems.
+           *-gnu* | gnu*) gl_cv_func_usleep_works="guessing yes" ;;
+                          # Guess yes on musl systems.
+           *-musl*)       gl_cv_func_usleep_works="guessing yes" ;;
+                          # Guess yes on systems that emulate the Linux system calls.
+           midipix*)      gl_cv_func_usleep_works="guessing yes" ;;
+                          # Guess no on native Windows.
+           mingw*)        gl_cv_func_usleep_works="guessing no" ;;
+                          # If we don't know, obey --enable-cross-guesses.
+           *)             gl_cv_func_usleep_works="$gl_cross_guess_normal" ;;
+         esac
+        ])])
+    case "$gl_cv_func_usleep_works" in
+      *yes) ;;
+      *)
+        REPLACE_USLEEP=1
+        ;;
+    esac
+  fi
+])