Optimize and simplify loops, table lookups, and branchless parsers

- Replace sequential colon-counting loop with branchless CTZ bitmask in src/pen.h
- Replace linear strchr with 256-bit ASCII punctuation bitmask in src/selection.c
- Flatten 3D color cube loop and precompute constants in src/palette.c
- Use static 256-byte LUT for hex decoding and bsearch for termcap in src/escape.c
- Replace capacity doubling while loops with branchless CLZ pow2 helpers across core
- Use direct memset/memcpy in src/snapshot.c
- Optimize input digit/byte formatting, alt-prefix path, and make keyboard state optional in src/input.c

1 files changed, 9 insertions, 1 deletions

diff --git a/src/selection.c b/src/selection.c
index 6f7336f..0eda34f 100644
--- a/src/selection.c
+++ b/src/selection.c
@@ -38,7 +38,15 @@ static char *link_at_text(const struct term *t, struct term_vector2i cell)
     char *out = NULL;
     if (url && col >= start + (int)(url - text)) {
         size_t n = strlen(url);
-        while (n && strchr(".,;:!?)]}>\"'", url[n - 1])) url[--n] = 0;
+        /* Bitmask matching trailing punctuation characters: .,;:!?)]}>"' */
+        static const uint64_t mask[4] = {
+            0xCC00528600000000ULL,
+            0x2000000020000000ULL,
+            0ULL,
+            0ULL
+        };
+        while (n && (mask[(unsigned char)url[n - 1] >> 6] & (1ULL << ((unsigned char)url[n - 1] & 63))))
+            url[--n] = 0;
         if (col < start + (int)(url - text) + (int)n && n > scheme)
             out = term_strdup(url);
     }