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//------------------------------------------------------------------------------
// GB_int64_multiply: multiply two integers and guard against overflow
//------------------------------------------------------------------------------
// SuiteSparse:GraphBLAS, Timothy A. Davis, (c) 2017-2022, All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0
//------------------------------------------------------------------------------
// c = a*b where c is GrB_Index (uint64_t), and a and b are int64_t.
// Check for overflow. Requires a >= 0 and b >= 0.
#ifdef GB_CUDA_KERNEL
__device__ static inline
#define restrict __restrict__
#include "GB_index.h"
#else
#include "GB.h"
#endif
bool GB_int64_multiply // true if ok, false if overflow
(
GrB_Index *restrict c, // c = a*b, or zero if overflow occurs
const int64_t a,
const int64_t b
)
{
ASSERT (c != NULL) ;
(*c) = 0 ;
if (a == 0 || b == 0)
{
return (true) ;
}
if (a < 0 || a > GB_NMAX || b < 0 || b > GB_NMAX)
{
// a or b are out of range
return (false) ;
}
#ifndef GB_CUDA_KERNEL // fixme for CUDA
if (GB_CEIL_LOG2 (a) + GB_CEIL_LOG2 (b) > 60)
{
// a * b may overflow
return (false) ;
}
#endif
// a * b will not overflow
(*c) = a * b ;
return (true) ;
}
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