www.pudn.com > QRcode.rar > BCH15_5.java
package jp.sourceforge.qrcode.codec.ecc;
public class BCH15_5 {
int[][] gf16;
boolean[] recieveData;
int numCorrectedError;
public BCH15_5(boolean[] source) {
gf16 = createGF16();
recieveData = source;
//printBit("Recieve data", recieveData);
}
public boolean[] correct() {
int[] s = calcSyndrome(recieveData);
int[] errorPos = detectErrorBitPosition(s);
boolean[] output = correctErrorBit(recieveData, errorPos);
return output;
}
int[][] createGF16() {
gf16 = new int[16][4];
int[] seed = {1, 1, 0, 0};
for (int i = 0; i < 4; i++)
gf16[i][i] = 1;
for (int i = 0; i < 4; i++)
gf16[4][i] = seed[i];
for (int i = 5; i < 16; i++) {
for (int j = 1; j < 4; j++) {
gf16[i][j] = gf16[i - 1][j - 1];
}
if (gf16[i - 1][3] == 1) {
for (int j = 0; j < 4; j++)
gf16[i][j] = (gf16[i][j] + seed[j]) % 2;
}
}
return gf16;
}
int searchElement(int[] x) {
int k;
for (k = 0; k < 15; k++) {
if ( x[0] == gf16[k][0]
&& x[1] == gf16[k][1]
&& x[2] == gf16[k][2]
&& x[3] == gf16[k][3]
) break;
}
return k;
}
/*String getInputString() {
String inputString = null;
InputStreamReader isr = new InputStreamReader(System.in);
BufferedReader br = new BufferedReader(isr);
try {
inputString = br.readLine();
} catch (IOException e){}
return inputString;
}*/
/*public int getInput() {
System.out.print("Input Number 0-127: ");
String str = getInputString();
int input = Integer.parseInt(str);
return input;
}*/
int[] getCode(int input) {
int[] f = new int[15];
int[] r = new int[8];
for (int i = 0; i < 15; i++) {
//1 + x + x^3
int w1, w2;
int yin;
w1 = r[7];
if (i < 7) {
yin = (input >> (6 - i)) % 2;
w2 = (yin + w1) % 2;
}
else {
yin = w1;
w2 = 0;
}
r[7] = (r[6] + w2) % 2;
r[6] = (r[5] + w2) % 2;
r[5] = r[4];
r[4] = (r[3] + w2) % 2;
r[3] = r[2];
r[2] = r[1];
r[1] = r[0];
r[0] = w2;
f[14 - i] = yin;
}
return f;
}
static String[] bitName = {"c0", "c1", "c2","c3", "c4", "c5","c6", "c7", "c8", "c9",
"d0", "d1", "d2", "d3", "d4", };
// static void printBit(String title, boolean[] bit) {
// System.out.print(title+": ");
// for (int i = 0; i < 15; i++) {
// if (i == 5) System.out.print(" ");
// System.out.print((bit[14 - i] == true) ? "1" : "0" );
// }
// System.out.print(" (");
// for (int i = 0; i < 15; i++) {
// if (i == 5) System.out.print(" ");
// System.out.print(bitName[14 - i]);
// }
// System.out.println(")");
// }
int addGF(int arg1, int arg2) {
int[] p = new int[4];
for (int m = 0; m < 4; m++) {
int w1 = (arg1 < 0 || arg1 >= 15) ? 0 : gf16[arg1][m];
int w2 = (arg2 < 0 || arg2 >= 15) ? 0 : gf16[arg2][m];
p[m] = (w1 + w2) % 2;
}
return searchElement(p);
}
/*void addRandomError(boolean[] f) {
Random random = new Random();
random.setSeed(System.currentTimeMillis());
int r;
int numError = 3; //[TODO]change number of error and check
for (int i = 0; i < numError; i++) {
r = random.nextInt();
if (r < 0) r = -r;
if (r / (double)Integer.MAX_VALUE < 0.9) {
int errorPos = r % 15;
f[errorPos] = !f[errorPos];
}
}
}*/
int[] calcSyndrome(boolean[] y) {
int[] s = new int[5];
int[] p = new int[4];
int k;
for (k = 0; k < 15; k++) {
if (y[k] == true) for (int m = 0; m < 4; m++)
p[m] = (p[m] + gf16[k][m]) % 2;
}
k = searchElement(p);
s[0] = (k >= 15)? -1 : k;
/*System.out.println("SyndromeS1 = " + ((s[0] == -1) ?
"0" :
"ƒ¿^" + String.valueOf(s[0]))
);*/
s[1] = (s[0] < 0) ? -1 : (s[0] * 2) % 15;
/*System.out.println("SyndromeS2 = " + ((s[1] == -1) ?
"0" :
"ƒ¿^" + String.valueOf(s[1]))
);*/
p = new int[4];
for (k = 0; k < 15; k++) {
if (y[k] == true) for (int m = 0; m < 4; m++)
p[m] = (p[m] + gf16[(k * 3) % 15][m]) % 2;
}
k = searchElement(p);
s[2] = (k >= 15) ? -1 : k;
/*System.out.println("SyndromeS3 = " + ((s[2] == -1) ?
"0" :
"ƒ¿^" + String.valueOf(s[2]))
);*/
s[3] = (s[1] < 0) ? -1 : (s[1] * 2) % 15;
/*System.out.println("SyndromeS4 = " + ((s[3] == -1) ?
"0" :
"ƒ¿^" + String.valueOf(s[3]))
);*/
p = new int[4];
for (k = 0; k < 15; k++) {
if (y[k] == true) for (int m = 0; m < 4; m++)
p[m] = (p[m] + gf16[(k * 5) % 15][m]) % 2;
}
k = searchElement(p);
s[4] = (k >= 15)? -1 : k;
/*System.out.println("SyndromeS5 = " + ((s[4] == -1) ?
"0" :
"ƒ¿^" + String.valueOf(s[4]))
);*/
return s;
}
int[] calcErrorPositionVariable(int[] s) {
int[] e = new int[4];
// calc ƒÐ1
e[0] = s[0];
//System.out.println("ƒÐ1 = " + String.valueOf(e[0]));
// calc ƒÐ2
int t = (s[0] + s[1]) % 15;
int mother = addGF(s[2], t);
mother = (mother >= 15) ? -1 : mother;
t = (s[2] + s[1]) % 15;
int child = addGF(s[4], t);
child = (child >= 15) ? -1 : child;
e[1] = (child < 0 && mother < 0) ? -1 : (child - mother + 15) % 15;
//System.out.println("ƒÐ2 = " + String.valueOf(e[1]));
// calc ƒÐ3
t = (s[1] + e[0]) % 15;
int t1 = addGF(s[2], t);
t = (s[0] + e[1]) % 15;
e[2] = addGF(t1, t);
//System.out.println("ƒÐ3 = " + String.valueOf(e[2]));
return e;
}
int[] detectErrorBitPosition(int[] s) {
int[] e = calcErrorPositionVariable(s);
int[] errorPos = new int[4];
if (e[0] == -1) {
//System.out.println("No errors.");
return errorPos;
}
else if (e[1] == -1) {
/*System.out.println("1 error. position is "+
String.valueOf(e[0]) +
" (" + bitName[e[0]] + ")")*/;
errorPos[0] = 1;
errorPos[1] = e[0];
return errorPos;
}
//else {
//System.out.println("2 or more errors.");
//}
int numError = 0;
int[] p;
int x3, x2, x1;
int t, t1, t2, anError;
//error detection
for (int i = 0; i < 15; i++) {
//calc x^3 + ƒÐ1*x^2 + ƒÐ2*x + ƒÐ3 = 0
x3 = (i * 3) % 15;
x2 = (i * 2) % 15;
x1 = i;
p = new int[4];
t = (e[0] + x2) % 15;
t1 = addGF(x3, t);
t = (e[1] + x1) % 15;
t2 = addGF(t, e[2]);
anError = addGF(t1,t2);
if (anError >= 15) {
/*System.out.println("Error found. position is " +
String.valueOf(i) +
"(" + bitName[i]+ ")");*/
errorPos[0]++;
errorPos[errorPos[0]] = i;
}
}
return errorPos;
}
boolean[] correctErrorBit(boolean[] y, int[] errorPos) {
//errorPos[0]‚ɃGƒ‰[‚Ì”AerrorPos[1],[2],[3]‚ÉŽÀۂ̈ʒu‚ª“ü‚Á‚Ä‚¢‚é
for (int i = 1; i <= errorPos[0]; i++)
y[errorPos[i]] = !y[errorPos[i]];
numCorrectedError = errorPos[0];
//printBit("Collected data", y);
return y;
}
public int getNumCorrectedError() {
return numCorrectedError;
}
/*boolean[] parseBooleanArray(String source)
{
int i = Integer.parseInt(source, 2);
boolean b[] = new boolean[source.length()];
for(int j = 0; j < 15; j++)
{
int t = i >> j & 1;
if(t == 1)
b[j] = true;
else
b[j] = false;
}
return b;
}*/
}