From 2fc396a607df86519a4bdea29f0fef9304118a0b Mon Sep 17 00:00:00 2001
From: Project Nayuki <me@nayuki.io>
Date: Thu, 23 Nov 2017 06:13:10 +0000
Subject: [PATCH] Implemented some supporting methods and changes for
 BitBuffer, QrSegment, QrTemplate.

---
 src/io/nayuki/fastqrcodegen/BitBuffer.java  | 42 +++++++++++++++++++++
 src/io/nayuki/fastqrcodegen/QrSegment.java  | 21 +++++++++++
 src/io/nayuki/fastqrcodegen/QrTemplate.java |  2 +-
 3 files changed, 64 insertions(+), 1 deletion(-)

diff --git a/src/io/nayuki/fastqrcodegen/BitBuffer.java b/src/io/nayuki/fastqrcodegen/BitBuffer.java
index a73158b..875d1f8 100644
--- a/src/io/nayuki/fastqrcodegen/BitBuffer.java
+++ b/src/io/nayuki/fastqrcodegen/BitBuffer.java
@@ -24,6 +24,7 @@
 package io.nayuki.fastqrcodegen;
 
 import java.util.Arrays;
+import java.util.Objects;
 
 
 final class BitBuffer {
@@ -54,6 +55,16 @@ final class BitBuffer {
 	}
 	
 	
+	public byte[] getBytes() {
+		if (bitLength % 8 != 0)
+			throw new IllegalStateException("Data is not a whole number of bytes");
+		byte[] result = new byte[bitLength / 8];
+		for (int i = 0; i < result.length; i++)
+			result[i] = (byte)(data[i >>> 2] >>> (~i << 3));
+		return result;
+	}
+	
+	
 	public void appendBits(int val, int len) {
 		if (len < 0 || len > 31 || val >>> len != 0)
 			throw new IllegalArgumentException("Value out of range");
@@ -76,4 +87,35 @@ final class BitBuffer {
 		bitLength += len;
 	}
 	
+	
+	public void appendBits(int[] vals, int len) {
+		Objects.requireNonNull(vals);
+		if (len == 0)
+			return;
+		if (len < 0 || len > vals.length * 32)
+			throw new IllegalArgumentException("Value out of range");
+		int wholeWords = len / 32;
+		int tailBits = len % 32;
+		if (tailBits > 0 && vals[wholeWords] << tailBits != 0)
+			throw new IllegalArgumentException("Last word must have low bits clear");
+		
+		while (bitLength + len > data.length * 32)
+			data = Arrays.copyOf(data, data.length * 2);
+		
+		int shift = bitLength % 32;
+		if (shift == 0) {
+			System.arraycopy(vals, 0, data, bitLength / 32, (len + 31) / 32);
+			bitLength += len;
+		} else {
+			for (int i = 0; i < wholeWords; i++) {
+				int word = vals[i];
+				data[bitLength >>> 5] |= word >>> shift;
+				bitLength += 32;
+				data[bitLength >>> 5] = word << (32 - shift);
+			}
+			if (tailBits > 0)
+				appendBits(vals[wholeWords] >>> (32 - tailBits), tailBits);
+		}
+	}
+	
 }
diff --git a/src/io/nayuki/fastqrcodegen/QrSegment.java b/src/io/nayuki/fastqrcodegen/QrSegment.java
index 44a9689..91f0545 100644
--- a/src/io/nayuki/fastqrcodegen/QrSegment.java
+++ b/src/io/nayuki/fastqrcodegen/QrSegment.java
@@ -167,6 +167,27 @@ public final class QrSegment {
 	}
 	
 	
+	// Package-private helper function.
+	static int getTotalBits(List<QrSegment> segs, int version) {
+		Objects.requireNonNull(segs);
+		if (version < 1 || version > 40)
+			throw new IllegalArgumentException("Version number out of range");
+		
+		long result = 0;
+		for (QrSegment seg : segs) {
+			Objects.requireNonNull(seg);
+			int ccbits = seg.mode.numCharCountBits(version);
+			// Fail if segment length value doesn't fit in the length field's bit-width
+			if (seg.numChars >= (1 << ccbits))
+				return -1;
+			result += 4L + ccbits + seg.bitLength;
+			if (result > Integer.MAX_VALUE)
+				return -1;
+		}
+		return (int)result;
+	}
+	
+	
 	
 	/*---- Constants ----*/
 	
diff --git a/src/io/nayuki/fastqrcodegen/QrTemplate.java b/src/io/nayuki/fastqrcodegen/QrTemplate.java
index 492e58c..b60ce81 100644
--- a/src/io/nayuki/fastqrcodegen/QrTemplate.java
+++ b/src/io/nayuki/fastqrcodegen/QrTemplate.java
@@ -300,7 +300,7 @@ final class QrTemplate {
 	// Returns the number of data bits that can be stored in a QR Code of the given version number, after
 	// all function modules are excluded. This includes remainder bits, so it might not be a multiple of 8.
 	// The result is in the range [208, 29648]. This could be implemented as a 40-entry lookup table.
-	private static int getNumRawDataModules(int ver) {
+	static int getNumRawDataModules(int ver) {
 		if (ver < MIN_VERSION || ver > MAX_VERSION)
 			throw new IllegalArgumentException("Version number out of range");
 		int result = (16 * ver + 128) * ver + 64;