From 914cf4b91ba8bdf63cd10a66f970c396329beeab Mon Sep 17 00:00:00 2001 From: Paul Eggert Date: Mon, 1 Aug 2022 00:38:32 -0700 Subject: [PATCH] Make time arithmetic more like comparison Since time comparison says X == X, have time arithmetic behave similarly for X - X. This should also be a bit faster due to not having to test for floats and NaNs. * src/timefns.c (time_arith, time_cmp): Simplify by not worrying about NaNs, which are not time values. (time_arith): Simplify by not worrying about subtracting nil from nil; the caller now handles this. (Ftime_subtract): Handle subtracting X from X specially. --- src/timefns.c | 44 +++++++++++--------------------------------- 1 file changed, 11 insertions(+), 33 deletions(-) diff --git a/src/timefns.c b/src/timefns.c index 25bfda513c2..c8becac8634 100644 --- a/src/timefns.c +++ b/src/timefns.c @@ -1074,27 +1074,9 @@ lispint_arith (Lisp_Object a, Lisp_Object b, bool subtract) static Lisp_Object time_arith (Lisp_Object a, Lisp_Object b, bool subtract) { - if (FLOATP (a) && !isfinite (XFLOAT_DATA (a))) - { - double da = XFLOAT_DATA (a); - double db = float_time (b); - return make_float (subtract ? da - db : da + db); - } enum timeform aform, bform; struct lisp_time ta = lisp_time_struct (a, &aform); - - if (FLOATP (b) && !isfinite (XFLOAT_DATA (b))) - return subtract ? make_float (-XFLOAT_DATA (b)) : b; - - /* Subtract nil from nil correctly, and handle other eq values - quicker while we're at it. Compare here rather than earlier, to - handle NaNs and check formats. */ - struct lisp_time tb; - if (BASE_EQ (a, b)) - bform = aform, tb = ta; - else - tb = lisp_time_struct (b, &bform); - + struct lisp_time tb = lisp_time_struct (b, &bform); Lisp_Object ticks, hz; if (FASTER_TIMEFNS && BASE_EQ (ta.hz, tb.hz)) @@ -1201,27 +1183,23 @@ See `format-time-string' for the various forms of a time value. For example, nil stands for the current time. */) (Lisp_Object a, Lisp_Object b) { + /* Subtract nil from nil correctly, and handle other eq values + quicker while we're at it. This means (time-subtract X X) does + not signal an error if X is not a valid time value, but that's OK. */ + if (BASE_EQ (a, b)) + return timespec_to_lisp ((struct timespec) {0}); + return time_arith (a, b, true); } -/* Return negative, 0, positive if a < b, a == b, a > b respectively. - Return positive if either a or b is a NaN; this is good enough - for the current callers. */ +/* Return negative, 0, positive if A < B, A == B, A > B respectively. + A and B should be Lisp time values. */ static int time_cmp (Lisp_Object a, Lisp_Object b) { - if ((FLOATP (a) && !isfinite (XFLOAT_DATA (a))) - || (FLOATP (b) && !isfinite (XFLOAT_DATA (b)))) - { - double da = FLOATP (a) ? XFLOAT_DATA (a) : 0; - double db = FLOATP (b) ? XFLOAT_DATA (b) : 0; - return da < db ? -1 : da != db; - } - /* Compare nil to nil correctly, and handle other eq values quicker - while we're at it. Compare here rather than earlier, to handle - NaNs. This means (time-equal-p X X) does not signal an error if - X is not a valid time value, but that's OK. */ + while we're at it. This means (time-equal-p X X) does not signal + an error if X is not a valid time value, but that's OK. */ if (BASE_EQ (a, b)) return 0; -- 2.39.2