[src/trunk]: src/sys/kern Implement format_bytes(), which pretty prints a giv...

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

details:   https://anonhg.NetBSD.org/src/rev/3284b6914f14
branches:  trunk
changeset: 472820:3284b6914f14
user:      lukem <lukem%NetBSD.org@localhost>
date:      Sun May 09 13:48:44 1999 +0000

description:
Implement format_bytes(), which pretty prints a given u_int64_t into a
given buffer, and if necessary, reducing the display width of the
number to fit in the buffer by increasing the units (from kilobytes
(2^10) through to exabytes (2^60)).

diffstat:

 sys/kern/kern_subr.c |  47 ++++++++++++++++++++++++++++++++++++++++++++---
 1 files changed, 44 insertions(+), 3 deletions(-)

diffs (64 lines):

diff -r f4977a2ac57e -r 3284b6914f14 sys/kern/kern_subr.c
--- a/sys/kern/kern_subr.c      Sun May 09 12:28:15 1999 +0000
+++ b/sys/kern/kern_subr.c      Sun May 09 13:48:44 1999 +0000
@@ -1,12 +1,12 @@
-/*     $NetBSD: kern_subr.c,v 1.47 1999/04/21 02:37:07 mrg Exp $       */
+/*     $NetBSD: kern_subr.c,v 1.48 1999/05/09 13:48:44 lukem Exp $     */
 
 /*-
- * Copyright (c) 1997, 1998 The NetBSD Foundation, Inc.
+ * Copyright (c) 1997, 1998, 1999 The NetBSD Foundation, Inc.
  * All rights reserved.
  *
  * This code is derived from software contributed to The NetBSD Foundation
  * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
- * NASA Ames Research Center.
+ * NASA Ames Research Center, and by Luke Mewburn.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -950,3 +950,44 @@
                }
        }
 }
+
+/*
+ * snprintf() `bytes' into `buf', reformatting it so that the number
+ * (plus a possible `xB' extension) fits into len bytes (including the
+ * terminating NUL).  Returns the number of bytes stored in buf, or -1
+ * if there was a problem.  E.g, given a len of 9: 
+ *     bytes           result
+ *     -----           ------
+ *     99999           `99999'
+ *     100000          `97 KB'
+ *     66715648        `65152 KB'
+ *     252215296       `240 MB'
+ */
+int
+format_bytes(buf, len, bytes)
+       char            *buf;
+       size_t           len;
+       u_int64_t        bytes;
+{
+               /* prefixes are: Kilo, Mega, Giga, Tera, Peta, Exa */
+       static const char prefixes[] = " KMGTPE";
+
+       int             i, r;
+       u_int64_t       max;
+
+       if (len > 0)
+               buf[0] = '\0';
+       if (len < 6)
+               return (-1);            /* not enough room for `xx yB\0' */
+
+       for (max = 1, i = 0; i < len - 4; i++)
+               max *= 10;
+       for (i = 0; bytes >= max && i < sizeof(prefixes); i++)
+               bytes /= 1024;
+
+       r = snprintf(buf, len, "%qd", (long long)bytes);
+       if (i > 0)
+               r += snprintf(buf + r, len - r, " %cB", prefixes[i]);
+
+       return (r);
+}