#ifndef FF_WWW_H
#define FF_WWW_H

#include "big_XXX.h"
#include "config_ff_WWW.h"

using namespace amcl;

#define HFLEN_WWW (FFLEN_WWW/2) /**< Useful for half-size RSA private key operations */
#define P_MBITS_WWW (MODBYTES_XXX*8)
#define P_TBITS_WWW (P_MBITS_WWW%BASEBITS_XXX)
#define P_EXCESS_WWW(a) (((a[NLEN_XXX-1])>>(P_TBITS_WWW))+1)
#define P_FEXCESS_WWW ((chunk)1<<(BASEBITS_XXX*NLEN_XXX-P_MBITS_WWW-1))


namespace WWW {

/* Finite Field Prototypes */
/**	@brief Copy one FF element of given length to another
 *
	@param x FF instance to be copied to, on exit = y
	@param y FF instance to be copied from
	@param n size of FF in BIGs

 */
extern void FF_copy(XXX::BIG *x,XXX::BIG *y,int n);
/**	@brief Initialize an FF element of given length from a 32-bit integer m
 *
	@param x FF instance to be copied to, on exit = m
	@param m integer
	@param n size of FF in BIGs
 */
extern void FF_init(XXX::BIG *x,sign32 m,int n);
/**	@brief Set FF element of given size to zero
 *
	@param x FF instance to be set to zero
	@param n size of FF in BIGs
 */
extern void FF_zero(XXX::BIG *x,int n);
/**	@brief Tests for FF element equal to zero
 *
	@param x FF number to be tested
	@param n size of FF in BIGs
	@return 1 if zero, else returns 0
 */
extern int FF_iszilch(XXX::BIG *x,int n);
/**	@brief  return parity of an FF, that is the least significant bit
 *
	@param x FF number
	@return 0 or 1
 */
extern int FF_parity(XXX::BIG *x);
/**	@brief  return least significant m bits of an FF
 *
	@param x FF number
	@param m number of bits to return. Assumed to be less than BASEBITS.
	@return least significant n bits as an integer
 */
extern int FF_lastbits(XXX::BIG *x,int m);
/**	@brief Set FF element of given size to unity
 *
	@param x FF instance to be set to unity
	@param n size of FF in BIGs
 */
extern void FF_one(XXX::BIG *x,int n);
/**	@brief Compares two FF numbers. Inputs must be normalised externally
 *
	@param x first FF number to be compared
	@param y second FF number to be compared
	@param n size of FF in BIGs
	@return -1 is x<y, 0 if x=y, 1 if x>y
 */
extern int FF_comp(XXX::BIG *x,XXX::BIG *y,int n);
/**	@brief addition of two FFs
 *
	@param x FF instance, on exit = y+z
	@param y FF instance
	@param z FF instance
	@param n size of FF in BIGs
 */
extern void FF_add(XXX::BIG *x,XXX::BIG *y,XXX::BIG *z,int n);
/**	@brief subtraction of two FFs
 *
	@param x FF instance, on exit = y-z
	@param y FF instance
	@param z FF instance
	@param n size of FF in BIGs
 */
extern void FF_sub(XXX::BIG *x,XXX::BIG *y,XXX::BIG *z,int n);
/**	@brief increment an FF by an integer,and normalise
 *
	@param x FF instance, on exit = x+m
	@param m an integer to be added to x
	@param n size of FF in BIGs
 */
extern void FF_inc(XXX::BIG *x,int m,int n);
/**	@brief Decrement an FF by an integer,and normalise
 *
	@param x FF instance, on exit = x-m
	@param m an integer to be subtracted from x
	@param n size of FF in BIGs
 */
extern void FF_dec(XXX::BIG *x,int m,int n);
/**	@brief Normalises the components of an FF
 *
	@param x FF instance to be normalised
	@param n size of FF in BIGs
 */
extern void FF_norm(XXX::BIG *x,int n);
/**	@brief Shift left an FF by 1 bit
 *
	@param x FF instance to be shifted left
	@param n size of FF in BIGs
 */
extern void FF_shl(XXX::BIG *x,int n);
/**	@brief Shift right an FF by 1 bit
 *
	@param x FF instance to be shifted right
	@param n size of FF in BIGs
 */
extern void FF_shr(XXX::BIG *x,int n);
/**	@brief Formats and outputs an FF to the console
 *
	@param x FF instance to be printed
	@param n size of FF in BIGs
 */
extern void FF_output(XXX::BIG *x,int n);
/**	@brief Formats and outputs an FF to the console, in raw form
 *
 	@param x FF instance to be printed
 	@param n size of FF in BIGs
 */
extern void FF_rawoutput(XXX::BIG *x,int n);
/**	@brief Formats and outputs an FF instance to an octet string
 *
	Converts an FF to big-endian base 256 form.
	@param S output octet string
	@param x FF instance to be converted to an octet string
	@param n size of FF in BIGs
 */
extern void FF_toOctet(octet *S,XXX::BIG *x,int n);
/**	@brief Populates an FF instance from an octet string
 *
	Creates FF from big-endian base 256 form.
	@param x FF instance to be created from an octet string
	@param S input octet string
	@param n size of FF in BIGs
 */
extern void FF_fromOctet(XXX::BIG *x,octet *S,int n);
/**	@brief Multiplication of two FFs
 *
	Uses Karatsuba method internally
	@param x FF instance, on exit = y*z
	@param y FF instance
	@param z FF instance
	@param n size of FF in BIGs
 */
extern void FF_mul(XXX::BIG *x,XXX::BIG *y,XXX::BIG *z,int n);
/**	@brief Reduce FF mod a modulus
 *
	This is slow
	@param x FF instance to be reduced mod m - on exit = x mod m
	@param m FF modulus
	@param n size of FF in BIGs
 */
extern void FF_mod(XXX::BIG *x,XXX::BIG *m,int n);
/**	@brief Square an FF
 *
	Uses Karatsuba method internally
	@param x FF instance, on exit = y^2
	@param y FF instance to be squared
	@param n size of FF in BIGs
 */
extern void FF_sqr(XXX::BIG *x,XXX::BIG *y,int n);
/**	@brief Reduces a double-length FF with respect to a given modulus
 *
	This is slow
	@param x FF instance, on exit = y mod z
	@param y FF instance, of double length 2*n
	@param z FF modulus
	@param n size of FF in BIGs
 */
extern void FF_dmod(XXX::BIG *x,XXX::BIG *y,XXX::BIG *z,int n);
/**	@brief Invert an FF mod a prime modulus
 *
	@param x FF instance, on exit = 1/y mod z
	@param y FF instance
	@param z FF prime modulus
	@param n size of FF in BIGs
 */
extern void FF_invmodp(XXX::BIG *x,XXX::BIG *y,XXX::BIG *z,int n);
/**	@brief Create an FF from a random number generator
 *
	@param x FF instance, on exit x is a random number of length n BIGs with most significant bit a 1
	@param R an instance of a Cryptographically Secure Random Number Generator
	@param n size of FF in BIGs
 */
extern void FF_random(XXX::BIG *x,csprng *R,int n);
/**	@brief Create a random FF less than a given modulus from a random number generator
 *
	@param x FF instance, on exit x is a random number < y
	@param y FF instance, the modulus
	@param R an instance of a Cryptographically Secure Random Number Generator
	@param n size of FF in BIGs
 */
extern void FF_randomnum(XXX::BIG *x,XXX::BIG *y,csprng *R,int n);
/**	@brief Calculate r=x^e mod m, side channel resistant
 *
	@param r FF instance, on exit = x^e mod p
	@param x FF instance
	@param e FF exponent
	@param m FF modulus
	@param n size of FF in BIGs
 */
extern void FF_skpow(XXX::BIG *r,XXX::BIG *x,XXX::BIG * e,XXX::BIG *m,int n);
/**	@brief Calculate r=x^e mod m, side channel resistant
 *
	For short BIG exponent
	@param r FF instance, on exit = x^e mod p
	@param x FF instance
	@param e BIG exponent
	@param m FF modulus
	@param n size of FF in BIGs
 */
extern void FF_skspow(XXX::BIG *r,XXX::BIG *x,XXX::BIG e,XXX::BIG *m,int n);
/**	@brief Calculate r=x^e mod m
 *
	For very short integer exponent
	@param r FF instance, on exit = x^e mod p
	@param x FF instance
	@param e integer exponent
	@param m FF modulus
	@param n size of FF in BIGs
 */
extern void FF_power(XXX::BIG *r,XXX::BIG *x,int e,XXX::BIG *m,int n);
/**	@brief Calculate r=x^e mod m
 *
	@param r FF instance, on exit = x^e mod p
	@param x FF instance
	@param e FF exponent
	@param m FF modulus
	@param n size of FF in BIGs
 */
extern void FF_pow(XXX::BIG *r,XXX::BIG *x,XXX::BIG *e,XXX::BIG *m,int n);
/**	@brief Test if an FF has factor in common with integer s
 *
	@param x FF instance to be tested
	@param s the supplied integer
	@param n size of FF in BIGs
	@return 1 if gcd(x,s)!=1, else return 0
 */
extern int FF_cfactor(XXX::BIG *x,sign32 s,int n);
/**	@brief Test if an FF is prime
 *
	Uses Miller-Rabin Method
	@param x FF instance to be tested
	@param R an instance of a Cryptographically Secure Random Number Generator
	@param n size of FF in BIGs
	@return 1 if x is (almost certainly) prime, else return 0
 */
extern int FF_prime(XXX::BIG *x,csprng *R,int n);
/**	@brief Calculate r=x^e.y^f mod m
 *
	@param r FF instance, on exit = x^e.y^f mod p
	@param x FF instance
	@param e BIG exponent
	@param y FF instance
	@param f BIG exponent
	@param m FF modulus
	@param n size of FF in BIGs
 */
extern void FF_pow2(XXX::BIG *r,XXX::BIG *x,XXX::BIG e,XXX::BIG *y,XXX::BIG f,XXX::BIG *m,int n);

}

#endif