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/* Copyright (c) 2003-2004, Roger Dingledine
* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
* Copyright (c) 2007-2020, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/**
* \file addsub.c
*
* \brief Helpers for addition and subtraction.
*
* Currently limited to non-wrapping (saturating) addition.
**/
#include "lib/intmath/addsub.h"
#include "lib/cc/compat_compiler.h"
/* Helper: safely add two uint32_t's, capping at UINT32_MAX rather
* than overflow */
uint32_t
tor_add_u32_nowrap(uint32_t a, uint32_t b)
{
/* a+b > UINT32_MAX check, without overflow */
if (PREDICT_UNLIKELY(a > UINT32_MAX - b)) {
return UINT32_MAX;
} else {
return a+b;
}
}
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