Lexicographic code: Difference between revisions

Revision as of 14:28, 6 March 2022

Revision as of 14:33, 6 March 2022

Line 789:

| volume = 48

| year = 2002}}</ref>

== Implementation ==

Following C generate lexicographic code and parameters are set for the Golay code (N=24, D=8).

<syntaxhighlight lang="c">

#include <stdio.h>

#include <stdlib.h>

int main() { /* GOLAY CODE generation */

int i, j, k;

int _pc[1<<16] = {0}; // PopCount Macro

for (i=0; i < (1<<16); i++)

for (j=0; j < 16; j++)

_pc[i] += (i>>j)&1;

#define pc(X) (_pc[(X)&0xffff] + _pc[((X)>>16)&0xffff])

#define N 24 // N bits

#define D 8 // D bits distance

unsigned int * z = malloc(1<<28);

for (i=j=0; i < (1<<N); i++)

{ // Scan all previous

for(k=j-1; k >= 0; k--) // lexicodes.

if( pc( z[k]^i ) < D) // Reverse cheking

break; // is way faster...

if (k == -1) { // Add new lexicode

for (k=0; k < N; k++) // & print it

printf("%d", (i>>k)&1);

printf(" : %d\n", j);

z[j++] = i;

}

}

}

</syntaxhighlight>

== Combinatorial game theory ==