1 files changed, 42 insertions, 0 deletions
diff --git a/sysdeps/generic/fast-jitter.h b/sysdeps/generic/fast-jitter.h
new file mode 100644
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+++ b/sysdeps/generic/fast-jitter.h
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+/* Fallback for fast jitter just return 0.
+   Copyright (C) 2019-2022 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _FAST_JITTER_H
+# define _FAST_JITTER_H
+
+# include <stdint.h>
+# include <hp-timing.h>
+
+/* Baseline just return 0.  We could create jitter using a clock or
+   'random_bits' but that may imply a syscall and the goal of
+   'get_fast_jitter' is minimal overhead "randomness" when such
+   randomness helps performance.  Adding high overhead the function
+   defeats the purpose.  */
+static inline uint32_t
+get_fast_jitter (void)
+{
+# if HP_TIMING_INLINE
+  hp_timing_t jitter;
+  HP_TIMING_NOW (jitter);
+  return (uint32_t) jitter;
+# else
+  return 0;
+# endif
+}
+
+#endif