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82 lines
2.1 KiB
C
82 lines
2.1 KiB
C
/* Copyright (c) 2003-2004, Roger Dingledine
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* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
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* Copyright (c) 2007-2018, The Tor Project, Inc. */
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/* See LICENSE for licensing information */
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/**
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* \file muldiv.c
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*
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* \brief Integer math related to multiplication, division, and rounding.
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**/
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#include "lib/intmath/muldiv.h"
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#include "lib/err/torerr.h"
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#include <stdlib.h>
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/** Return the lowest x such that x is at least <b>number</b>, and x modulo
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* <b>divisor</b> == 0. If no such x can be expressed as an unsigned, return
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* UINT_MAX. Asserts if divisor is zero. */
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unsigned
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round_to_next_multiple_of(unsigned number, unsigned divisor)
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{
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raw_assert(divisor > 0);
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if (UINT_MAX - divisor + 1 < number)
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return UINT_MAX;
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number += divisor - 1;
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number -= number % divisor;
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return number;
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}
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/** Return the lowest x such that x is at least <b>number</b>, and x modulo
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* <b>divisor</b> == 0. If no such x can be expressed as a uint32_t, return
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* UINT32_MAX. Asserts if divisor is zero. */
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uint32_t
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round_uint32_to_next_multiple_of(uint32_t number, uint32_t divisor)
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{
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raw_assert(divisor > 0);
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if (UINT32_MAX - divisor + 1 < number)
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return UINT32_MAX;
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number += divisor - 1;
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number -= number % divisor;
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return number;
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}
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/** Return the lowest x such that x is at least <b>number</b>, and x modulo
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* <b>divisor</b> == 0. If no such x can be expressed as a uint64_t, return
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* UINT64_MAX. Asserts if divisor is zero. */
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uint64_t
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round_uint64_to_next_multiple_of(uint64_t number, uint64_t divisor)
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{
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raw_assert(divisor > 0);
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if (UINT64_MAX - divisor + 1 < number)
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return UINT64_MAX;
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number += divisor - 1;
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number -= number % divisor;
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return number;
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}
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/* Helper: return greatest common divisor of a,b */
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static uint64_t
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gcd64(uint64_t a, uint64_t b)
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{
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while (b) {
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uint64_t t = b;
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b = a % b;
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a = t;
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}
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return a;
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}
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/* Given a fraction *<b>numer</b> / *<b>denom</b>, simplify it.
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* Requires that the denominator is greater than 0. */
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void
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simplify_fraction64(uint64_t *numer, uint64_t *denom)
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{
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raw_assert(denom);
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uint64_t gcd = gcd64(*numer, *denom);
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*numer /= gcd;
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*denom /= gcd;
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}
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