From 1e3a66df459750071a9003a131d7f2c319dbb331 Mon Sep 17 00:00:00 2001 From: Gregory Heytings Date: Fri, 12 May 2023 21:56:31 +0000 Subject: [PATCH] Add an assertion in, and a commentary for, 'get_nearby_bol_pos' * src/xdisp.c: (get_nearby_bol_pos): Document the function, and add an assertion on its return value. --- src/xdisp.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/src/xdisp.c b/src/xdisp.c index 30a32896aba..6572d14d934 100644 --- a/src/xdisp.c +++ b/src/xdisp.c @@ -3545,7 +3545,7 @@ init_iterator (struct it *it, struct window *w, The corresponding function 'get_medium_narrowing_zv' (and 'medium_narrowing_zv' field in 'struct it') is not used to set the - end limit of a the restriction, which is again unnecessary, but to + end limit of the restriction, which is again unnecessary, but to determine, in 'reseat', whether the iterator has moved far enough from its original position, and whether the start position of the restriction must be computed anew. @@ -3613,10 +3613,15 @@ get_medium_narrowing_zv (struct window *w, ptrdiff_t pos) return min ((pos / len + 1) * len, ZV); } +/* Find the position of the last BOL before POS, unless it is too far + away. The buffer portion in which the search occurs is gradually + enlarged: [POS-500..POS], [POS-5500..POS-500], + [POS-55500..POS-5500], and finally [POS-555500..POS-55500]. Return + BEGV-1 if no BOL was found in [POS-555500..POS]. */ static ptrdiff_t get_nearby_bol_pos (ptrdiff_t pos) { - ptrdiff_t start, pos_bytepos, cur, next, found, bol = BEGV - 1; + ptrdiff_t start, pos_bytepos, cur, next, found, bol = BEGV - 1, init_pos = pos; int dist; for (dist = 500; dist <= 500000; dist *= 10) { @@ -3633,10 +3638,11 @@ get_nearby_bol_pos (ptrdiff_t pos) break; } if (bol >= BEGV || start == BEGV) - return bol; + break; else pos = pos - dist < BEGV ? BEGV : pos - dist; } + eassert (bol <= init_pos); return bol; } -- 2.39.2