//?------------------------------------------------------------------------
//????????File:?bch_bm.c
//????????Date:?April?3?2002
//?Description:?An?encoder/decoder?for?binary?BCH?codes
//??????????????Error?correction?using?the?BERLEKAMP-MASSEY?ALGORITHM
//?------------------------------------------------------------------------
//?This?program?is?complementary?material?for?the?book:
//
//?R.H.?Morelos-Zaragoza?The?Art?of?Error?Correcting?Coding?Wiley?2002.
//
//?ISBN?0471?49581?6
//
//?This?and?other?programs?are?available?at?http://the-art-of-ecc.com
//
//?You?may?use?this?program?for?academic?and?personal?purposes?only.?
//?If?this?program?is?used?to?perform?simulations?whose?results?are?
//?published?in?a?journal?or?book?please?refer?to?the?book?above.
//
//?The?use?of?this?program?in?a?commercial?product?requires?explicit?
//?written?permission?from?the?author.?The?author?is?not?responsible?or?
//?liable?for?damage?or?loss?that?may?be?caused?by?the?use?of?this?program.?
//
//?Copyright?（c）?2002.?Robert?H.?Morelos-Zaragoza.?All?rights?reserved.
//?------------------------------------------------------------------------

#include?
#include?

int?????????????m?n?length?k?t?d;
int?????????????p[21];
int?????????????alpha_to[1048576]?index_of[1048576]?g[548576];
int?????????????recd[1048576]?data[1048576]?bb[548576];
int?????????????seed;
int?????????????numerr?errpos[1024]?decerror?=?0;


void?
read_p（）
/*
?*	Read?m?the?degree?of?a?primitive?polynomial?p（x）?used?to?compute?the
?*	Galois?field?GF（2**m）.?Get?precomputed?coefficients?p[]?of?p（x）.?Read
?*	the?code?length.
?*/
{
	int			i?ninf;

	printf（“\nEnter?a?value?of?m?such?that?the?code?length?is\n“）;
	printf（“2**（m-1）?-?1?????do?{
	???printf（“Enter?m?（between?2?and?20）:?“）;
	???scanf（“%d“?&m）;
????}?while?（?!（m>1）?||?!（m<21）?）;
	for?（i=1;?i		p[i]?=?0;
	p[0]?=?p[m]?=?1;
	if?（m?==?2）			p[1]?=?1;
	else?if?（m?==?3）	p[1]?=?1;
	else?if?（m?==?4）	p[1]?=?1;
	else?if?（m?==?5）	p[2]?=?1;
	else?if?（m?==?6）	p[1]?=?1;
	else?if?（m?==?7）	p[1]?=?1;
	else?if?（m?==?8）	p[4]?=?p[5]?=?p[6]?=?1;
	else?if?（m?==?9）	p[4]?=?1;
	else?if?（m?==?10）	p[3]?=?1;
	else?if?（m?==?11）	p[2]?=?1;
	else?if?（m?==?12）	p[3]?=?p[4]?=?p[7]?=?1;
	else?if?（m?==?13）	p[1]?=?p[3]?=?p[4]?=?1;
	else?if?（m?==?14）	p[1]?=?p[11]?=?p[12]?=?1;
	else?if?（m?==?15）	p[1]?=?1;
	else?if?（m?==?16）	p[2]?=?p[3]?=?p[5]?=?1;
	else?if?（m?==?17）	p[3]?=?1;
	else?if?（m?==?18）	p[7]?=?1;
	else?if?（m?==?19）	p[1]?=?p[5]?=?p[6]?=?1;
	else?if?（m?==?20）	p[3]?=?1;
	printf（“p（x）?=?“）;
????n?=?1;
	for?（i?=?0;?i?<=?m;?i++）?{
????????n?*=?2;
		printf（“%1d“?p[i]）;
????????}
	printf（“\n“）;
	n?=?n?/?2?-?1;
	ninf?=?（n?+?1）?/?2?-?1;
	do??{
		printf（“Enter?code?length?（%d?		scanf（“%d“?&length）;
	}?while?（?!（（length?<=?n）&&（length>ninf））?）;
}


void?
generate_gf（）
/*
?*?Generate?field?GF（2*

?屬性????????????大小?????日期????時間???名稱
-----------?---------??----------?-----??----
?????文件???????15015??2009-05-25?10:39??bch\bch_bm.c