From e942581488a139eaf82d77f4d430cf18ace6c728 Mon Sep 17 00:00:00 2001 From: Paul Eggert Date: Mon, 18 Sep 2023 14:09:24 -0700 Subject: [PATCH] Improve XUNTAG comment * src/lisp.h (XUNTAG): Shorten (and I hope clarify) new comment. --- src/lisp.h | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/src/lisp.h b/src/lisp.h index de6746f1c07..79ce8e5fa8e 100644 --- a/src/lisp.h +++ b/src/lisp.h @@ -808,10 +808,9 @@ INLINE void } /* Extract A's pointer value, assuming A's Lisp type is TYPE and the - extracted pointer's type is CTYPE *. - Note that the second term vanishes if EMACS_INT is wider than pointers - and the tag is in the upper bits (ie, USE_LSB_TAG=0); this makes - untagging slightly cheaper in that case. */ + extracted pointer's type is CTYPE *. When !USE_LSB_TAG this simply + extracts A's low-order bits, as (uintptr_t) LISP_WORD_TAG (type) is + always zero then. */ #define XUNTAG(a, type, ctype) \ ((ctype *) ((uintptr_t) XLP (a) - (uintptr_t) LISP_WORD_TAG (type))) -- 2.39.5