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/*
* percent.c - Take percentage of a number
*
* Copyright (C) 2006 Theodore Ts'o <tytso@mit.edu>
*
* %Begin-Header%
* This file may be redistributed under the terms of the GNU Library
* General Public License, version 2.
* %End-Header%
*/
#include "config.h"
#include "e2p.h"
#include <stdlib.h>
/*
* We work really hard to calculate this accurately, while avoiding
* an overflow. "Is there a hyphen in anal-retentive?" :-)
*/
unsigned int e2p_percent(int percent, unsigned int base)
{
unsigned int mask = ~((1 << (sizeof(unsigned int) - 1) * 8) - 1);
if (!percent)
return 0;
if (100 % percent == 0)
return base / (100 / percent);
if (mask & base)
return (base / 100) * percent;
return base * percent / 100;
}
#ifdef DEBUG
#include <unistd.h>
#include <stdio.h>
main(int argc, char **argv)
{
unsigned int base;
int percent;
char *p;
int log_block_size = 0;
if (argc != 3) {
fprintf(stderr, "Usage: %s percent base\n", argv[0]);
exit(1);
}
percent = strtoul(argv[1], &p, 0);
if (p[0] && p[1]) {
fprintf(stderr, "Bad percent: %s\n", argv[1]);
exit(1);
}
base = strtoul(argv[2], &p, 0);
if (p[0] && p[1]) {
fprintf(stderr, "Bad base: %s\n", argv[2]);
exit(1);
}
printf("%d percent of %u is %u.\n", percent, base,
e2p_percent(percent, base));
exit(0);
}
#endif
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