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/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright 2017 Jason king
*/
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/debug.h>
#include "libcmdutils.h"
/* The largest suffix that can fit, aka an exabyte (2^60 / 10^18) */
#define INDEX_MAX (6)
/* Verify INDEX_MAX fits */
CTASSERT(INDEX_MAX * 10 < sizeof (uint64_t) * 8);
void
nicenum_scale(uint64_t n, size_t units, char *buf, size_t buflen,
uint32_t flags)
{
uint64_t divamt = 1024;
uint64_t divisor = 1;
int index = 0;
int rc = 0;
char u;
if (units == 0)
units = 1;
if (n > 0) {
n *= units;
if (n < units)
goto overflow;
}
if (flags & NN_DIVISOR_1000)
divamt = 1000;
/*
* This tries to find the suffix S(n) such that
* S(n) <= n < S(n+1), where S(n) = 2^(n*10) | 10^(3*n)
* (i.e. 1024/1000, 1,048,576/1,000,000, etc). Stop once S(n)
* is the largest prefix supported (i.e. don't bother computing
* and checking S(n+1). Since INDEX_MAX should be the largest
* suffix that fits (currently an exabyte), S(INDEX_MAX + 1) is
* never checked as it would overflow.
*/
while (index < INDEX_MAX) {
uint64_t newdiv = divisor * divamt;
/* CTASSERT() guarantee these never trip */
VERIFY3U(newdiv, >=, divamt);
VERIFY3U(newdiv, >=, divisor);
if (n < newdiv)
break;
divisor = newdiv;
index++;
}
u = " KMGTPE"[index];
if (index == 0) {
rc = snprintf(buf, buflen, "%llu", n);
} else if (n % divisor == 0) {
/*
* If this is an even multiple of the base, always display
* without any decimal precision.
*/
rc = snprintf(buf, buflen, "%llu%c", n / divisor, u);
} else {
/*
* We want to choose a precision that reflects the best choice
* for fitting in 5 characters. This can get rather tricky
* when we have numbers that are very close to an order of
* magnitude. For example, when displaying 10239 (which is
* really 9.999K), we want only a single place of precision
* for 10.0K. We could develop some complex heuristics for
* this, but it's much easier just to try each combination
* in turn.
*/
int i;
for (i = 2; i >= 0; i--) {
if ((rc = snprintf(buf, buflen, "%.*f%c", i,
(double)n / divisor, u)) <= 5)
break;
}
}
if (rc + 1 > buflen || rc < 0)
goto overflow;
return;
overflow:
/* prefer a more verbose message if possible */
if (buflen > 10)
(void) strlcpy(buf, "<overflow>", buflen);
else
(void) strlcpy(buf, "??", buflen);
}
void
nicenum(uint64_t num, char *buf, size_t buflen)
{
nicenum_scale(num, 1, buf, buflen, 0);
}
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