From 14a66370e294f6cb14360e7ae85a05e56810edd7 Mon Sep 17 00:00:00 2001
From: Matthieu Schaller <schaller@strw.leidenuniv.nl>
Date: Tue, 18 Sep 2018 17:47:48 +0200
Subject: [PATCH] Better documentation of the functions in timeline.h.
Corrected get_min_active_bin() to report the correct minimal bin on the 1st
step.
---
src/timeline.h | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/src/timeline.h b/src/timeline.h
index 4078a904c3..38727def50 100644
--- a/src/timeline.h
+++ b/src/timeline.h
@@ -62,24 +62,30 @@ get_integer_timestep(timebin_t bin) {
* @brief Returns the time bin corresponding to a given time_step size.
*
* Assumes that integertime_t maps to an unsigned long long.
+ * Given our definitions, this is log_2 of the time_step rounded down minus one.
+ *
+ * We use a fast (but exact for any non-zero value) logarithm in base 2
+ * calculation based on the bit representation of the number:
+ * log_2(x) = (number of bits in the type) - (number of leading 0-bits in x) - 1
*/
__attribute__((const)) static INLINE timebin_t
get_time_bin(integertime_t time_step) {
/* ((int) log_2(time_step)) - 1 */
- return (timebin_t)(62 - intrinsics_clzll(time_step));
+ return (timebin_t)((8 * sizeof(integertime_t) - 2) -
+ intrinsics_clzll((unsigned long long)time_step));
}
/**
* @brief Returns the physical time interval corresponding to a time bin.
*
* @param bin The time bin of interest.
- * @param timeBase the minimal time-step size of the simulation.
+ * @param time_base the minimal time-step size of the simulation.
*/
__attribute__((const)) static INLINE double get_timestep(timebin_t bin,
- double timeBase) {
+ double time_base) {
- return get_integer_timestep(bin) * timeBase;
+ return get_integer_timestep(bin) * time_base;
}
/**
@@ -142,7 +148,7 @@ __attribute__((const)) static INLINE timebin_t
get_min_active_bin(integertime_t ti_current, integertime_t ti_old) {
const timebin_t min_bin = get_max_active_bin(ti_current - ti_old);
- return (ti_old > 0) ? min_bin : (min_bin - 1);
+ return min_bin;
}
#endif /* SWIFT_TIMELINE_H */
--
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