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| author | Paul Eggert <eggert@cs.ucla.edu> | 2024-06-22 20:42:04 -0400 |
|---|---|---|
| committer | Paul Eggert <eggert@cs.ucla.edu> | 2024-06-22 20:42:55 -0400 |
| commit | 2b848a4e504319cce150000a2c3855f66d89714b (patch) | |
| tree | c83882d2a6eb83fdd1cac9411f63b49fdd042f2f /src/timefns.c | |
| parent | 77e3a56507d0f06662d1be692194a4e40f6ffc68 (diff) | |
Fix FIXME in comment
* src/timefns.c (decode_float_time): Explain why the code
can use large precision here, removing a FIXME by updating
the containing comment.
Diffstat (limited to 'src/timefns.c')
| -rw-r--r-- | src/timefns.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/src/timefns.c b/src/timefns.c index 0ecbb6e6793..746e422ffb6 100644 --- a/src/timefns.c +++ b/src/timefns.c @@ -414,9 +414,11 @@ decode_float_time (double t, struct lisp_time *result) else { int scale = double_integer_scale (t); - /* FIXME: `double_integer_scale` often returns values that are - "pessimistic" (i.e. larger than necessary), so 3.5 gets converted - to (7881299347898368 . 2251799813685248) rather than (7 . 2). + /* Because SCALE treats trailing zeros in T as significant, + on typical platforms with IEEE floating point + (time-convert 3.5 t) yields (7881299347898368 . 2251799813685248), + a precision of 2**-51 s, not (7 . 2), a precision of 0.5 s. + Although numerically correct, this generates largish integers. On 64bit systems, this should not matter very much, tho. */ eassume (scale < flt_radix_power_size); |