/***********************************************************************
?*?Copyright?Henry?Minsky?（hqm@alum.mit.edu）?1991-2009
?*
?*?This?software?library?is?licensed?under?terms?of?the?GNU?GENERAL
?*?PUBLIC?LICENSE
?*?
?*
?*?RSCODE?is?free?software:?you?can?redistribute?it?and/or?modify
?*?it?under?the?terms?of?the?GNU?General?Public?License?as?published?by
?*?the?Free?Software?Foundation?either?version?3?of?the?License?or
?*?（at?your?option）?any?later?version.
?*
?*?RSCODE?is?distributed?in?the?hope?that?it?will?be?useful
?*?but?WITHOUT?ANY?WARRANTY;?without?even?the?implied?warranty?of
?*?MERCHANTABILITY?or?FITNESS?FOR?A?PARTICULAR?PURPOSE.??See?the
?*?GNU?General?Public?License?for?more?details.
?*
?*?You?should?have?received?a?copy?of?the?GNU?General?Public?License
?*?along?with?Rscode.??If?not?see?.
?*
?*?Commercial?licensing?is?available?under?a?separate?license?please
?*?contact?author?for?details.
?*
?*?Source?code?is?available?at?http://rscode.sourceforge.net
?*?Berlekamp-Peterson?and?Berlekamp-Massey?Algorithms?for?error-location
?*
?*?From?Cain?Clark?“Error-Correction?Coding?For?Digital?Communications“?pp.?205.
?*
?*?This?finds?the?coefficients?of?the?error?locator?polynomial.
?*
?*?The?roots?are?then?found?by?looking?for?the?values?of?a^n
?*?where?evaluating?the?polynomial?yields?zero.
?*
?*?Error?correction?is?done?using?the?error-evaluator?equation??on?pp?207.
?*
?*/

#include?
#include?“ecc.h“

/*?The?Error?Locator?Polynomial?also?known?as?Lambda?or?Sigma.?Lambda[0]?==?1?*/
static?int?Lambda[MAXDEG];

/*?The?Error?Evaluator?Polynomial?*/
static?int?Omega[MAXDEG];

/*?local?ANSI?declarations?*/
static?int?compute_discrepancy（int?lambda[]?int?S[]?int?L?int?n）;
static?void?init_gamma（int?gamma[]）;
static?void?compute_modified_omega?（void）;
static?void?mul_z_poly?（int?src[]）;

/*?error?locations?found?using?Chien‘s?search*/
static?int?ErrorLocs[256];
static?int?NErrors;

/*?erasure?flags?*/
static?int?ErasureLocs[256];
static?int?NErasures;

/*?From??Cain?Clark?“Error-Correction?Coding?For?Digital?Communications“?pp.?216.?*/
void
Modified_Berlekamp_Massey?（void）
{	
??int?n?L?L2?k?d?i;
??int?psi[MAXDEG]?psi2[MAXDEG]?D[MAXDEG];
??int?gamma[MAXDEG];
	
??/*?initialize?Gamma?the?erasure?locator?polynomial?*/
??init_gamma（gamma）;

??/*?initialize?to?z?*/
??copy_poly（D?gamma）;
??mul_z_poly（D）;
	
??copy_poly（psi?gamma）;	
??k?=?-1;?L?=?NErasures;
	
??for?（n?=?NErasures;?n?	
????d?=?compute_discrepancy（psi?synBytes?L?n）;
		
????if?（d?!=?0）?{
		
??????/*?psi2?=?psi?-?d*D?*/
??????for?（i?=?0;?i?		
		
??????if?（L?	L2?=?n-k;
	k?=?n-L;
	/*?D?=?scale_poly（ginv（d）?psi）;?*/
	for?（i?=?0;?i?	L?=?L2;
??????}
			
??????/*?psi?=?psi2?*/
??????for?（i?=?0;?i?????}
		
????mul_z_poly（D）;
??}
	
??for（i?=?0;?i?