[src/trunk]: src/external/bsd/top/dist/machine simplify and explain

[christos <christos%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/ef2a4416acd9
branches:  trunk
changeset: 456219:ef2a4416acd9
user:      christos <christos%NetBSD.org@localhost>
date:      Sat Apr 27 14:10:01 2019 +0000

description:
simplify and explain

diffstat:

 external/bsd/top/dist/machine/m_netbsd.c |  27 +++++++++++++--------------
 1 files changed, 13 insertions(+), 14 deletions(-)

diffs (54 lines):

diff -r afdd47c25f70 -r ef2a4416acd9 external/bsd/top/dist/machine/m_netbsd.c
--- a/external/bsd/top/dist/machine/m_netbsd.c  Sat Apr 27 12:12:25 2019 +0000
+++ b/external/bsd/top/dist/machine/m_netbsd.c  Sat Apr 27 14:10:01 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: m_netbsd.c,v 1.22 2019/04/26 19:39:19 christos Exp $   */
+/*     $NetBSD: m_netbsd.c,v 1.23 2019/04/27 14:10:01 christos Exp $   */
 
 /*
  * top - a top users display for Unix
@@ -37,12 +37,12 @@
  *             Andrew Doran <ad%NetBSD.org@localhost>
  *
  *
- * $Id: m_netbsd.c,v 1.22 2019/04/26 19:39:19 christos Exp $
+ * $Id: m_netbsd.c,v 1.23 2019/04/27 14:10:01 christos Exp $
  */
 #include <sys/cdefs.h>
 
 #ifndef lint
-__RCSID("$NetBSD: m_netbsd.c,v 1.22 2019/04/26 19:39:19 christos Exp $");
+__RCSID("$NetBSD: m_netbsd.c,v 1.23 2019/04/27 14:10:01 christos Exp $");
 #endif
 
 #include <sys/param.h>
@@ -882,19 +882,18 @@
 countable(char *p, size_t l)
 {
        static const char digits[] = "0123456789";
-       size_t first = strcspn(p, digits);
-       size_t last = strspn(p + first, digits);
-       size_t len = first + last;
-       if (p[len] || last == 0)
-               return p;
-       if (len < l)
+       size_t first = strcspn(p, digits);              // non digits
+       size_t last = strspn(p + first, digits);        // trailing digits
+       size_t len = first + last;                      
+       if (p[len] || last == 0)        // should be total and must have digits
                return p;
-       if (l < last + 1)
+       if (len < l)                    // if shorter, done
+               return p;
+       if (l < last + 1)               // if not enough for digits, done
                return p;
-       size_t start = l - last - 1;
-       p[start] = '*';
-       memmove(p + start + 1, p + first, len - first);
-       p[l] = '\0';
+       size_t start = l - last - 1;    // compute starting point
+       p[start] = '*';                 // put a star
+       memmove(p + start + 1, p + first, last + 1);    // move digits and NUL
        return p;
 }