Scalar_arithmetic.cpp

/*******************************************************************/
/***  FILE :     Scalar_arithmetic.c                             ***/
/***  AUTHOR:    David P Jacobs                                  ***/
/***  PROGRAMMER: Sekhar Muddana                                 ***/
/***  PUBLIC ROUTINES:                                           ***/
/***      Scalar S_init()                                        ***/
/***      Scalar S_zero()                                        ***/
/***      Scalar S_one()                                         ***/
/***      Scalar S_minus1()                                      ***/
/***      Scalar S_minus()                                       ***/
/***      Scalar S_add()                                         ***/
/***      Scalar S_sub()                                         ***/
/***      Scalar S_div()                                         ***/
/***      Scalar S_mul()                                         ***/
/***      Scalar S_inv()                                         ***/
/***  PRIVATE ROUTINES:                                          ***/
/***      void Print_inv_table()                                 ***/
/***  MODULE DESCRIPTION:                                        ***/
/***      This module contains routines dealing with Scalar      ***/
/***      Arithmatic.                                            ***/
/*******************************************************************/

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>

#include "Scalar_arithmetic.h"
#include "Build_defs.h"
#include "driver.h"

Scalar Prime;
Scalar Inverse_table[PRIME_BOUND];
uint16_t _d_;
uint32_t _c_;

void S_init() {
    Prime = GetField();    /* Initialize the global variable Prime. */

    _d_ = Prime;
    _c_ = (~(0U)) / _d_ + 1;

/* Initialize the global table of inverses. */
    for (Scalar i = 1; i < Prime; i++) {
        for (Scalar j = 1; j < Prime; j++) {
            if (_modp(i * j) == 1) {
                Inverse_table[i] = j;
                break;
            }
        }
    }
}