monomial.h

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// Copyright (C) 2009 Sebastian Pancratz                                     //
//                                                                           //
// Distributed under the terms of the GNU General Public License as          //
// published by the Free Software Foundation; either version 2 of the        //
// License, or (at your option) any later version.                           //
//                                                                           //
// http://www.gnu.org/licenses/                                              //

#ifndef _MONOMIAL_H_
#define _MONOMIAL_H_

#include <inttypes.h>


// Number of variables (less one)                                            //

#define _N_  2

// Data types                                                                //

typedef uint64_t monomial_t;

#if _N_ < 3
typedef uint32_t exponent_t;
#elif _N_ < 7
typedef uint16_t exponent_t;
#else
typedef uint8_t exponent_t;
#endif

// Object-like macros                                                        //

#define MON_BITS_PER_EXP (64/(_N_+1))

#define MON_BITMASK_BLOCK ((monomial_t) ((((monomial_t)1) << MON_BITS_PER_EXP) - ((monomial_t)1)))

#define MON_BITMASK_ALL (64 % (_N_ + 1) ? ((monomial_t) ((((monomial_t)1) << ((_N_ + 1) * MON_BITS_PER_EXP)) - ((monomial_t)1))) : 0xFFFFFFFFFFFFFFFFULL)

#if _N_ == 1
#define MON_VARS "XY"
#elif _N_ == 2
#define MON_VARS "XYZ"
#elif _N_ == 3
#define MON_VARS "WXYZ"
#elif _N_ == 4
#define MON_VARS "VWXYZ"
#elif _N_ == 5
#define MON_VARS "UVWYXZ"
#elif _N_ == 6
#define MON_VARS "TUVWXYZ"
#else
#define MON_VARS "STUVWXYZ"
#endif

// Function-like macros                                                      //

// Initialization

#define MON_INIT(x)  ((x) = 0)

#define MON_CLEAR(x)

#define MON_SET(x, y)  ((x) = (y))

#define MON_SWAP(x, y)  { monomial_t _t_ = (x); (x) = (y); (y) = _t_; }

#define MON_ONE(x)  ((x) = 0)


// Access

#define MON_GET_EXP(x, i)  ((exponent_t) (((x) >> ((i) * MON_BITS_PER_EXP)) & MON_BITMASK_BLOCK))

#define MON_SET_EXP(x, i, e)  ((x) = (((x) & (MON_BITMASK_ALL - (MON_BITMASK_BLOCK << ((i) * MON_BITS_PER_EXP)))) | (((monomial_t)(e)) << ((i) * MON_BITS_PER_EXP))))

#define MON_INC_EXP(x, i, e)  ((x) = ((x) + (((monomial_t)(e)) << ((i) * MON_BITS_PER_EXP))))

#define MON_DEC_EXP(x, i, e)  ((x) = ((x) - (((monomial_t)(e)) << ((i) * MON_BITS_PER_EXP))))


// Comparison

#define MON_CMP_INVLEX(x, y)  (((x) < (y)) ? -1 : ((x) > (y) ? 1 : 0))

#define MON_IS_ONE(x)  ((x) == 0)


// Multiplication and division

#define MON_MUL(x, y, z)  ((x) = (y) + (z))

#define MON_DIV(x, y, z)  ((x) = (y) - (z))


// Function declarations                                                     //

uint32_t mon_degree(monomial_t op);

int32_t mon_divides(monomial_t x, monomial_t y);

char * mon_to_string(monomial_t x, const uint8_t n);
char * mon_to_string_pretty(monomial_t x, const uint8_t n, const char * vars);
monomial_t mon_from_string(char * str);

monomial_t * mon_generate_by_degree(uint32_t * len, const uint8_t n, const uint32_t d);

#endif

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