overflow.hpp File Reference

Overflow-checked integer arithmetic for monomial exponents and degree sums. More...

#include "exceptions.hpp"
#include <cassert>
#include <M2/config.h>

Go to the source code of this file.

Namespaces
namespace	safe

Macros
#define	HAS_BUILTIN(x)
#define	expect_false(x)
#define	expect_true(x)

Functions
void	safe::ov (const char *msg)
static int32_t	safe::fits_7 (int32_t x, const char *msg)
static int32_t	safe::fits_15 (int32_t x, const char *msg)
static int32_t	safe::fits_31 (int32_t x, const char *msg)
static int32_t	safe::fits_7 (int32_t x)
static int32_t	safe::fits_15 (int32_t x)
static int32_t	safe::fits_31 (int32_t x)
static int32_t	safe::over_1 (int32_t x)
static int32_t	safe::over_2 (int32_t x)
static int32_t	safe::over_4 (int32_t x)
static int32_t	safe::add (int32_t x, int32_t y, const char *msg)
static int32_t	safe::add (int32_t x, int32_t y)
static int32_t	safe::add_to (int32_t &x, int32_t y, const char *msg)
static int32_t	safe::add_to (int32_t &x, int32_t y)
static int32_t	safe::sub (int32_t x, int32_t y, const char *msg)
static int32_t	safe::sub (int32_t x, int32_t y)
static int32_t	safe::sub_from (int32_t &x, int32_t y, const char *msg)
static int32_t	safe::sub_from (int32_t &x, int32_t y)
static int32_t	safe::sub_pos (int32_t x, int32_t y, const char *msg)
static int32_t	safe::sub_pos (int32_t x, int32_t y)
static int32_t	safe::minus (int32_t x, const char *msg)
static int32_t	safe::minus (int32_t x)
static int32_t	safe::pos_add (int32_t x, int32_t y, const char *msg)
static int32_t	safe::pos_add (int32_t x, int32_t y)
static int32_t	safe::pos_add_2 (int32_t x, int32_t y, const char *msg)
static int32_t	safe::pos_add_2 (int32_t x, int32_t y)
static int32_t	safe::pos_add_4 (int32_t x, int32_t y, const char *msg)
static int32_t	safe::pos_add_4 (int32_t x, int32_t y)
static int32_t	safe::mult (int32_t x, int32_t y, const char *msg)
static int32_t	safe::mult (int32_t x, int32_t y)
static int32_t	safe::mult_by (int32_t &x, int32_t y, const char *msg)
static int32_t	safe::mult_by (int32_t &x, int32_t y)
static int32_t	safe::div (int32_t x, int32_t y, const char *msg)
static int32_t	safe::div (int32_t x, int32_t y)
static int32_t	safe::div_by (int32_t &x, int32_t y, const char *msg)
static int32_t	safe::div_by (int32_t &x, int32_t y)

Detailed Description

Overflow-checked integer arithmetic for monomial exponents and degree sums.

Note

AI-generated documentation. Verify against the source before relying on it.

Provides the safe:: arithmetic helpers (add, add_to, sub, sub_from, sub_pos, pos_add) and the bit-width predicates fits_7 / fits_15 / ... that monomial-arithmetic paths in the engine route through. Exponents are stored as int32_t; a silent wraparound in e + e' would not just produce a wrong answer but would put the result below either input, breaking the monomial-order invariant and potentially making a Groebner basis loop forever or reduce to a non-zero canonical form. Each helper performs the operation, checks the bound, and on failure calls safe::ov(msg) — which (in overflow.cpp) throws exc::overflow_exception.

The bound checks are bit-pattern tests against a high-bit mask (e.g. ((uint32_t)x & ~0x7f) != 0), not compiler overflow intrinsics; the header pulls in __has_builtin only to wire expect_false / expect_true macros around the bad path via __builtin_expect, so the success path stays branch-predicted. Callers include the aring-* family, the GB variants, the resolution engines, and the monoid / monomial-order machinery.

See also

exceptions.hpp

imonorder.hpp

Definition in file overflow.hpp.