overflow.h File Reference

A helper file for checking overflows. More...

#include <limits.h>

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Macros
#define	LONG_LONG_MAX   LLONG_MAX
#define	LONG_LONG_MIN   LLONG_MIN
#define	ADDITION_OVERFLOW_CHECK(a, x, tmax, tmin)
	checks for overflows while adding two numbers More...
#define	SUBTRACTION_OVERFLOW_CHECK(a, x, tmax, tmin)
	checks for overflows while subtracting two numbers More...
#define	MULTIPLICATION_OVERFLOW_CHECK(a, x, tmax, tmin)
	checks for overflows while multiplying two numbers More...
#define	ADDITION_OVERFLOW_CHECK_i32(a, x)   ADDITION_OVERFLOW_CHECK(a, x, INT_MAX, INT_MIN)
	checks for overflows while adding two 32 bit signed numbers More...
#define	SUBTRACTION_OVERFLOW_CHECK_i32(a, x)   SUBTRACTION_OVERFLOW_CHECK(a, x, INT_MAX, INT_MIN)
	checks for overflows while subtracting two 32 bit signed numbers More...
#define	MULTIPLICATION_OVERFLOW_CHECK_i32(a, x)   MULTIPLICATION_OVERFLOW_CHECK(a, x, INT_MAX, INT_MIN)
	checks for overflows while multiplying two 32 bit signed numbers More...
#define	ADDITION_OVERFLOW_CHECK_i64(a, x)   ADDITION_OVERFLOW_CHECK(a, x, LONG_LONG_MAX, LONG_LONG_MIN)
	checks for overflows while adding two 64 bit signed numbers More...
#define	SUBTRACTION_OVERFLOW_CHECK_i64(a, x)   SUBTRACTION_OVERFLOW_CHECK(a, x, LONG_LONG_MAX, LONG_LONG_MIN)
	checks for overflows while subtracting two 64 bit signed numbers More...
#define	MULTIPLICATION_OVERFLOW_CHECK_i64(a, x)   MULTIPLICATION_OVERFLOW_CHECK(a, x, LONG_LONG_MAX, LONG_LONG_MIN)
	checks for overflows while multiplying two 64 bit signed numbers More...

Detailed Description

A helper file for checking overflows.

Macro Definition Documentation

ADDITION_OVERFLOW_CHECK

#define ADDITION_OVERFLOW_CHECK	(		a,
			x,
			tmax,
			tmin
	)

Value:

    ( \
    ((x) > 0) || ((a) > (tmax) - (x))) /* `a + x` would overflow */ \
    || ((x) < 0) || ((a) < (tmin) - (x))) /* `a + x` would underflow */ \
)

checks for overflows while adding two numbers

Parameters

a
x
tmax	: the max value of the type in question
tmin	: the min value of the type in question

Returns

1 : overflow will happen

0 : no overflow

ADDITION_OVERFLOW_CHECK_i32

#define ADDITION_OVERFLOW_CHECK_i32	(		a,
			x
	)		ADDITION_OVERFLOW_CHECK(a, x, INT_MAX, INT_MIN)

checks for overflows while adding two 32 bit signed numbers

Parameters

a
x

Returns

1 : overflow will happen

0 : no overflow

ADDITION_OVERFLOW_CHECK_i64

#define ADDITION_OVERFLOW_CHECK_i64	(		a,
			x
	)		ADDITION_OVERFLOW_CHECK(a, x, LONG_LONG_MAX, LONG_LONG_MIN)

checks for overflows while adding two 64 bit signed numbers

Parameters

a
x

Returns

1 : overflow will happen

0 : no overflow

MULTIPLICATION_OVERFLOW_CHECK

#define MULTIPLICATION_OVERFLOW_CHECK	(		a,
			x,
			tmax,
			tmin
	)

Value:

    ( \
    (x) != 0 && ((x) * (a) < 0 \
    || ((a) > (tmax) / (x)) /* `a * x` would overflow */ \
    || (((a) < (tmin) / (x)))) /* `a * x` would underflow */ \
)

checks for overflows while multiplying two numbers

Parameters

a
x
tmax	: the max value of the type in question
tmin	: the min value of the type in question

Returns

1 : overflow will happen

0 : no overflow

MULTIPLICATION_OVERFLOW_CHECK_i32

#define MULTIPLICATION_OVERFLOW_CHECK_i32	(		a,
			x
	)		MULTIPLICATION_OVERFLOW_CHECK(a, x, INT_MAX, INT_MIN)

checks for overflows while multiplying two 32 bit signed numbers

Parameters

a
x

Returns

1 : overflow will happen

0 : no overflow

MULTIPLICATION_OVERFLOW_CHECK_i64

#define MULTIPLICATION_OVERFLOW_CHECK_i64	(		a,
			x
	)		MULTIPLICATION_OVERFLOW_CHECK(a, x, LONG_LONG_MAX, LONG_LONG_MIN)

checks for overflows while multiplying two 64 bit signed numbers

Parameters

a
x

Returns

1 : overflow will happen

0 : no overflow

SUBTRACTION_OVERFLOW_CHECK

#define SUBTRACTION_OVERFLOW_CHECK	(		a,
			x,
			tmax,
			tmin
	)

Value:

    ( \
    (((x) < 0) || ((a) > (tmax) + (x))) /* `a - x` would overflow */ \
    || (((x) > 0) || ((a) < (tmin) + (x))) /* `a - x` would underflow */ \
)

checks for overflows while subtracting two numbers

Parameters

a
x
tmax	: the max value of the type in question
tmin	: the min value of the type in question

Returns

1 : overflow will happen

0 : no overflow

SUBTRACTION_OVERFLOW_CHECK_i32

#define SUBTRACTION_OVERFLOW_CHECK_i32	(		a,
			x
	)		SUBTRACTION_OVERFLOW_CHECK(a, x, INT_MAX, INT_MIN)

checks for overflows while subtracting two 32 bit signed numbers

Parameters

a
x

Returns

1 : overflow will happen

0 : no overflow

SUBTRACTION_OVERFLOW_CHECK_i64

#define SUBTRACTION_OVERFLOW_CHECK_i64	(		a,
			x
	)		SUBTRACTION_OVERFLOW_CHECK(a, x, LONG_LONG_MAX, LONG_LONG_MIN)

checks for overflows while subtracting two 64 bit signed numbers

Parameters

a
x

Returns

1 : overflow will happen

0 : no overflow