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Now uses new Reed Solomon encoder code

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git-svn-id: https://zxing.googlecode.com/svn/trunk@709 59b500cc-1b3d-0410-9834-0bbf25fbcc57
This commit is contained in:
srowen 2008-11-15 20:23:32 +00:00
parent c5d81d76d1
commit 247e7c95bb
2 changed files with 33 additions and 100 deletions
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4
core/src/com/google/zxing/qrcode/encoder/ByteArray.java
View file

@ -52,6 +52,10 @@ public final class ByteArray {
return bytes[index] & 0xff; return bytes[index] & 0xff;
} }
public void set(int index, int value) {
bytes[index] = (byte) value;
}
public int size() { public int size() {
return size; return size;
} }

129
core/src/com/google/zxing/qrcode/encoder/Encoder.java
View file

@ -16,11 +16,10 @@
package com.google.zxing.qrcode.encoder; package com.google.zxing.qrcode.encoder;
import java.util.Vector; import com.google.zxing.common.reedsolomon.ReedSolomonEncoder;
import com.google.zxing.common.reedsolomon.GF256;
// class GF_Poly; import java.util.Vector;
// #include "util/reedsolomon/galois_field.h"
// #include "util/reedsolomon/galois_poly.h"
/** /**
* @author satorux@google.com (Satoru Takabayashi) - creator * @author satorux@google.com (Satoru Takabayashi) - creator
@ -278,9 +277,6 @@ private static final ECPolyInfo kECPolynomials[] = {
27, 101, 184, 127, 3, 5, 8, 163, 238 }), 27, 101, 184, 127, 3, 5, 8, 163, 238 }),
}; };
private static final int kFieldSize = 8;
private static GF_Poly[] g_ec_polynomials = new GF_Poly[kMaxNumECBytes + 1];
private static final class BlockPair { private static final class BlockPair {
private ByteArray dataBytes; private ByteArray dataBytes;
@ -514,8 +510,8 @@ private static final ECPolyInfo kECPolynomials[] = {
// the result in "num_data_bytes_in_block", and "num_ec_bytes_in_block". See table 12 in 8.5.1 of // the result in "num_data_bytes_in_block", and "num_ec_bytes_in_block". See table 12 in 8.5.1 of
// JISX0510:2004 (p.30) // JISX0510:2004 (p.30)
static void GetNumDataBytesAndNumECBytesForBlockID(int num_total_bytes, int num_data_bytes, static void GetNumDataBytesAndNumECBytesForBlockID(int num_total_bytes, int num_data_bytes,
int num_rs_blocks, int block_id, Integer num_data_bytes_in_block, int num_rs_blocks, int block_id, int[] num_data_bytes_in_block,
Integer num_ec_bytes_in_block) { int[] num_ec_bytes_in_block) {
Debug.DCHECK_LT(block_id, num_rs_blocks); Debug.DCHECK_LT(block_id, num_rs_blocks);
// num_rs_blocks_in_group2 = 196 % 5 = 1 // num_rs_blocks_in_group2 = 196 % 5 = 1
final int num_rs_blocks_in_group2 = num_total_bytes % num_rs_blocks; final int num_rs_blocks_in_group2 = num_total_bytes % num_rs_blocks;
@ -548,11 +544,11 @@ private static final ECPolyInfo kECPolynomials[] = {
num_rs_blocks_in_group2)); num_rs_blocks_in_group2));
if (block_id < num_rs_blocks_in_group1) { if (block_id < num_rs_blocks_in_group1) {
num_data_bytes_in_block = num_data_bytes_in_group1; num_data_bytes_in_block[0] = num_data_bytes_in_group1;
num_ec_bytes_in_block = num_ec_bytes_in_group1; num_ec_bytes_in_block[0] = num_ec_bytes_in_group1;
} else { } else {
num_data_bytes_in_block = num_data_bytes_in_group2; num_data_bytes_in_block[0] = num_data_bytes_in_group2;
num_ec_bytes_in_block = num_ec_bytes_in_group2; num_ec_bytes_in_block[0] = num_ec_bytes_in_group2;
} }
} }
@ -572,11 +568,11 @@ private static final ECPolyInfo kECPolynomials[] = {
int max_num_ec_bytes = 0; int max_num_ec_bytes = 0;
// Since, we know the number of reedsolmon blocks, we can initialize the vector with the number. // Since, we know the number of reedsolmon blocks, we can initialize the vector with the number.
Vector<BlockPair> blocks = new Vector<BlockPair>(num_rs_blocks); Vector blocks = new Vector(num_rs_blocks);
for (int i = 0; i < num_rs_blocks; ++i) { for (int i = 0; i < num_rs_blocks; ++i) {
Integer num_data_bytes_in_block = new Integer(0); int[] num_data_bytes_in_block = new int[1];
Integer num_ec_bytes_in_block = new Integer(0); int[] num_ec_bytes_in_block = new int[1];
GetNumDataBytesAndNumECBytesForBlockID( GetNumDataBytesAndNumECBytesForBlockID(
num_total_bytes, num_data_bytes, num_rs_blocks, i, num_total_bytes, num_data_bytes, num_rs_blocks, i,
num_data_bytes_in_block, num_ec_bytes_in_block); num_data_bytes_in_block, num_ec_bytes_in_block);
@ -585,19 +581,19 @@ private static final ECPolyInfo kECPolynomials[] = {
ByteArray ec_bytes = new ByteArray(); ByteArray ec_bytes = new ByteArray();
blocks.addElement(new BlockPair(data_bytes, ec_bytes)); blocks.addElement(new BlockPair(data_bytes, ec_bytes));
data_bytes.set(bits, data_bytes_offset, num_data_bytes_in_block); data_bytes.set(bits, data_bytes_offset, num_data_bytes_in_block[0]);
GenerateECBytes(data_bytes, num_ec_bytes_in_block, ec_bytes); GenerateECBytes(data_bytes, num_ec_bytes_in_block[0], ec_bytes);
max_num_data_bytes = Math.max(max_num_data_bytes, data_bytes.size()); max_num_data_bytes = Math.max(max_num_data_bytes, data_bytes.size());
max_num_ec_bytes = Math.max(max_num_ec_bytes, ec_bytes.size()); max_num_ec_bytes = Math.max(max_num_ec_bytes, ec_bytes.size());
data_bytes_offset += num_data_bytes_in_block; data_bytes_offset += num_data_bytes_in_block[0];
} }
Debug.DCHECK_EQ(num_data_bytes, data_bytes_offset); Debug.DCHECK_EQ(num_data_bytes, data_bytes_offset);
// First, place data blocks. // First, place data blocks.
for (int i = 0; i < max_num_data_bytes; ++i) { for (int i = 0; i < max_num_data_bytes; ++i) {
for (int j = 0; j < blocks.size(); ++j) { for (int j = 0; j < blocks.size(); ++j) {
final ByteArray data_bytes = blocks.elementAt(j).getDataBytes(); final ByteArray data_bytes = ((BlockPair) blocks.elementAt(j)).getDataBytes();
if (i < data_bytes.size()) { if (i < data_bytes.size()) {
result.AppendBits(data_bytes.at(i), 8); result.AppendBits(data_bytes.at(i), 8);
} }
@ -606,7 +602,7 @@ private static final ECPolyInfo kECPolynomials[] = {
// Then, place error correction blocks. // Then, place error correction blocks.
for (int i = 0; i < max_num_ec_bytes; ++i) { for (int i = 0; i < max_num_ec_bytes; ++i) {
for (int j = 0; j < blocks.size(); ++j) { for (int j = 0; j < blocks.size(); ++j) {
final ByteArray ec_bytes = blocks.elementAt(j).getErrorCorrectionBytes(); final ByteArray ec_bytes = ((BlockPair) blocks.elementAt(j)).getErrorCorrectionBytes();
if (i < ec_bytes.size()) { if (i < ec_bytes.size()) {
result.AppendBits(ec_bytes.at(i), 8); result.AppendBits(ec_bytes.at(i), 8);
} }
@ -620,6 +616,18 @@ private static final ECPolyInfo kECPolynomials[] = {
return false; return false;
} }
private static void GenerateECBytes(ByteArray data_bytes, int num_ec_bytes_in_block, ByteArray ec_bytes) {
int numDataBytes = data_bytes.size();
int[] toEncode = new int[numDataBytes + ec_bytes.size()];
for (int i = 0; i < numDataBytes; i++) {
toEncode[i] = data_bytes.at(i);
}
new ReedSolomonEncoder(GF256.QR_CODE_FIELD).encode(toEncode, num_ec_bytes_in_block);
for (int i = 0; i < ec_bytes.size(); i++) {
ec_bytes.set(i, toEncode[numDataBytes + i]);
}
}
// Append mode info. On success, store the result in "bits" and return true. On error, return // Append mode info. On success, store the result in "bits" and return true. On error, return
// false. // false.
static boolean AppendModeInfo(int mode, BitVector bits) { static boolean AppendModeInfo(int mode, BitVector bits) {
@ -768,85 +776,6 @@ private static final ECPolyInfo kECPolynomials[] = {
return true; return true;
} }
// Only call once
static {
InitECPolynomials();
}
// Initialize "g_ec_polynomials" with numbers in kECPolynomials.
private static void InitECPolynomials() {
final GaloisField field = GaloisField.GetField(kFieldSize);
for (int i = 0; i < kECPolynomials.length; ++i) {
final ECPolyInfo ec_poly_info = kECPolynomials[i];
final int ec_length = ec_poly_info.ec_length;
vector<GF_Element> *coeffs = new vector<GF_Element>;
// The number of coefficients is one more than "ec_length". That's why the termination
// condition is <= instead of <.
for (int j = 0; j <= ec_length; ++j) {
// We need exp'ed numbers for later use.
final int coeff = field.Exp(ec_poly_info.coeffs[j]);
coeffs.push_back(coeff);
}
// Reverse the coefficients since the numbers in kECPolynomials are ordered in reverse order
// to the order GF_Poly expects.
reverse(coeffs.begin(), coeffs.end());
GF_Poly ec_poly = new GF_Poly(coeffs, GaloisField.GetField(kFieldSize));
g_ec_polynomials[ec_length] = ec_poly;
}
}
// Get error correction polynomials. The polynomials are defined in Appendix A of JISX0510 2004
// (p. 59). In the appendix, they use exponential notations for the polynomials. We need to apply
// GaloisField.Log() to all coefficients generated by the function to compare numbers with the
// ones in the appendix.
//
// Example:
// - Input: 17
// - Output (in reverse order)
// {119,66,83,120,119,22,197,83,249,41,143,134,85,53,125,99,79}
// - Log()'ed output (in reverse order)
// {0,43,139,206,78,43,239,123,206,214,147,24,99,150,39,243,163,136}
private static final GF_Poly GetECPoly(int ec_length) {
Debug.DCHECK_GE(kMaxNumECBytes, ec_length);
final GF_Poly ec_poly = g_ec_polynomials[ec_length];
Debug.DCHECK(ec_poly);
return ec_poly;
}
// Generate error correction bytes of "ec_length".
//
// Example:
// - Input: {32,65,205,69,41,220,46,128,236}, ec_length = 17
// - Output: {42,159,74,221,244,169,239,150,138,70,237,85,224,96,74,219,61}
private static void GenerateECBytes(final ByteArray data_bytes, int ec_length, ByteArray ec_bytes) {
// First, fill the vector with "ec_length" copies of 0. They are low-order zero coefficients.
vector<GF_Element> *coeffs = new vector<GF_Element>(ec_length, 0);
// Then copy data_bytes backward.
copy(data_bytes.rbegin(), data_bytes.rend(), back_inserter(*coeffs));
// Now we have data polynomial.
GF_Poly data_poly(coeffs, GaloisField.GetField(kFieldSize));
// Get error correction polynomial.
final GF_Poly &ec_poly = GetECPoly(ec_length);
pair<GF_Poly*, GF_Poly*> divrem = GF_Poly.DivRem(data_poly, ec_poly);
// Basically, the coefficients in the remainder polynomial are the error correction bytes.
GF_Poly *remainder = divrem.second;
ec_bytes.reserve(ec_length);
// However, high-order zero cofficients in the remainder polynomial are ommited. We should add
// zero by ourselvs.
final int num_pruned_zero_coeffs = ec_length - (remainder.degree() + 1);
for (int i = 0; i < num_pruned_zero_coeffs; ++i) {
ec_bytes.appendByte(0);
}
// Copy the remainder numbers to "ec_bytes".
for (int i = remainder.degree(); i >= 0; --i) {
ec_bytes.appendByte(remainder.coeff(i));
}
Debug.DCHECK_EQ(ec_length, ec_bytes.size());
}
// Check if "byte1" and "byte2" can compose a valid Kanji letter (2-byte Shift_JIS letter). The // Check if "byte1" and "byte2" can compose a valid Kanji letter (2-byte Shift_JIS letter). The
// numbers are from http://ja.wikipedia.org/wiki/Shift_JIS. // numbers are from http://ja.wikipedia.org/wiki/Shift_JIS.
private static boolean IsValidKanji(final int byte1, final int byte2) { private static boolean IsValidKanji(final int byte1, final int byte2) {