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//------------------------------------------------------------------------------
// GB_size_t_multiply: multiply two size_t and guard against overflow
//------------------------------------------------------------------------------
// SuiteSparse:GraphBLAS, Timothy A. Davis, (c) 2017-2022, All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0
//------------------------------------------------------------------------------
// c = a*b but check for overflow
#include "GB.h"
GB_PUBLIC
bool GB_size_t_multiply // true if ok, false if overflow
(
size_t *c, // c = a*b, or zero if overflow occurs
const size_t a,
const size_t b
)
{
ASSERT (c != NULL) ;
(*c) = 0 ;
if (a == 0 || b == 0)
{
return (true) ;
}
if (a > SIZE_MAX / 2 || b > SIZE_MAX / 2)
{
// a or b are out of range
return (false) ;
}
// a + b is now safe to compute
if ((a + b) > (SIZE_MAX / GB_IMIN (a,b)))
{
// a * b may overflow
return (false) ;
}
// a * b will not overflow
(*c) = a * b ;
return (true) ;
}
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