formalize code for reading unsigned bytes

git-svn-id: https://svn.code.sf.net/p/jackcess/code/jackcess/trunk@255 f203690c-595d-4dc9-a70b-905162fa7fd2

4 files changed, 61 insertions, 18 deletions

diff --git a/src/java/com/healthmarketscience/jackcess/ByteUtil.java b/src/java/com/healthmarketscience/jackcess/ByteUtil.java
index 054affa..876187a 100644
--- a/src/java/com/healthmarketscience/jackcess/ByteUtil.java
+++ b/src/java/com/healthmarketscience/jackcess/ByteUtil.java
@@ -140,14 +140,38 @@ public final class ByteUtil {
       offset += 2;
     }
     
-    int rtn = toUnsignedInt(buffer.get(offset));
-    rtn += (toUnsignedInt(buffer.get(offset + (1 * offInc))) << 8);
-    rtn += (toUnsignedInt(buffer.get(offset + (2 * offInc))) << 16);
-    rtn &= 0xFFFFFF;
+    int rtn = getUnsignedByte(buffer, offset);
+    rtn += (getUnsignedByte(buffer, offset + (1 * offInc)) << 8);
+    rtn += (getUnsignedByte(buffer, offset + (2 * offInc)) << 16);
     return rtn;
   }
 
   /**
+   * Read a 3 byte int from a buffer
+   * @param buffer Buffer containing the bytes
+   * @return The int
+   */
+  public static int getUnsignedByte(ByteBuffer buffer) {
+    int pos = buffer.position();
+    int rtn = getUnsignedByte(buffer, pos);
+    buffer.position(pos + 1);
+    return rtn;
+  }
+
+  /**
+   * Read a 3 byte int from a buffer
+   * @param buffer Buffer containing the bytes
+   * @param offset Offset at which to read the byte
+   * @return The int
+   */
+  public static int getUnsignedByte(ByteBuffer buffer, int offset) {  
+    return asUnsignedByte(buffer.get(offset));
+  }
+
+  
+  /**
+   * @param buffer Buffer containing the bytes
+   * @param order  the order of the bytes of the int
    * @return an int from the current position in the given buffer, read using
    *         the given ByteOrder
    */
@@ -159,6 +183,9 @@ public final class ByteUtil {
   }
   
   /**
+   * @param buffer Buffer containing the bytes
+   * @param offset Offset at which to start reading the int
+   * @param order  the order of the bytes of the int
    * @return an int from the given position in the given buffer, read using
    *         the given ByteOrder
    */
@@ -174,6 +201,9 @@ public final class ByteUtil {
   /**
    * Writes an int at the current position in the given buffer, using the
    * given ByteOrder
+   * @param buffer buffer into which to insert the int
+   * @param val Int to insert
+   * @param order the order to insert the bytes of the int
    */
   public static void putInt(ByteBuffer buffer, int val, ByteOrder order) {
     int offset = buffer.position();
@@ -184,6 +214,10 @@ public final class ByteUtil {
   /**
    * Writes an int at the given position in the given buffer, using the
    * given ByteOrder
+   * @param buffer buffer into which to insert the int
+   * @param val Int to insert
+   * @param offset offset at which to insert the int
+   * @param order the order to insert the bytes of the int
    */
   public static void putInt(ByteBuffer buffer, int val, int offset,
                            ByteOrder order)
@@ -251,6 +285,15 @@ public final class ByteUtil {
   }
   
   /**
+   * Convert a byte array to a hexadecimal string for display
+   * @param buffer Buffer to display, starting at offset 0
+   * @return The display String
+   */
+  public static String toHexString(byte[] array) {
+    return toHexString(ByteBuffer.wrap(array), 0, array.length);
+  }
+  
+  /**
    * Convert a byte buffer to a hexadecimal string for display
    * @param buffer Buffer to display, starting at offset 0
    * @param offset Offset at which to start reading the buffer
@@ -341,7 +384,7 @@ public final class ByteUtil {
   /**
    * @return the byte value converted to an unsigned int value
    */
-  public static int toUnsignedInt(byte b) { 
+  public static int asUnsignedByte(byte b) { 
     return b & 0xFF;
   }
   
diff --git a/src/java/com/healthmarketscience/jackcess/Column.java b/src/java/com/healthmarketscience/jackcess/Column.java
index c262b84..9d3583a 100644
--- a/src/java/com/healthmarketscience/jackcess/Column.java
+++ b/src/java/com/healthmarketscience/jackcess/Column.java
@@ -452,7 +452,7 @@ public class Column implements Comparable<Column> {
                               lvalDefinition.length);
       }
 
-      int rowNum = ByteUtil.toUnsignedInt(def.get());
+      int rowNum = ByteUtil.getUnsignedByte(def);
       int pageNum = ByteUtil.get3ByteInt(def, def.position());
       ByteBuffer lvalPage = getPageChannel().createPageBuffer();
       
@@ -486,7 +486,7 @@ public class Column implements Comparable<Column> {
           
           // read next page information
           lvalPage.position(rowStart);
-          rowNum = ByteUtil.toUnsignedInt(lvalPage.get());
+          rowNum = ByteUtil.getUnsignedByte(lvalPage);
           pageNum = ByteUtil.get3ByteInt(lvalPage);
 
           // update rowEnd and remainingLen based on chunkLength
diff --git a/src/java/com/healthmarketscience/jackcess/Index.java b/src/java/com/healthmarketscience/jackcess/Index.java
index fb21194..8ba49f8 100644
--- a/src/java/com/healthmarketscience/jackcess/Index.java
+++ b/src/java/com/healthmarketscience/jackcess/Index.java
@@ -138,8 +138,8 @@ public class Index implements Comparable<Index> {
           ++pos;
         }
         if(pos < len) {
-          return ((ByteUtil.toUnsignedInt(left[pos]) <
-                   ByteUtil.toUnsignedInt(right[pos])) ? -1 : 1);
+          return ((ByteUtil.asUnsignedByte(left[pos]) <
+                   ByteUtil.asUnsignedByte(right[pos])) ? -1 : 1);
         }
         return ((left.length < right.length) ? -1 :
                 ((left.length > right.length) ? 1 : 0));
@@ -466,8 +466,8 @@ public class Index implements Comparable<Index> {
   {
     // note, "header" data is in LITTLE_ENDIAN format, entry data is in
     // BIG_ENDIAN format
-    int numCompressedBytes = indexPage.get(
-        getFormat().OFFSET_INDEX_COMPRESSED_BYTE_COUNT);
+    int numCompressedBytes = ByteUtil.getUnsignedByte(
+        indexPage, getFormat().OFFSET_INDEX_COMPRESSED_BYTE_COUNT);
     int entryMaskLength = getFormat().SIZE_INDEX_ENTRY_MASK;
     int entryMaskPos = getFormat().OFFSET_INDEX_ENTRY_MASK;
     int entryPos = entryMaskPos + getFormat().SIZE_INDEX_ENTRY_MASK;
@@ -1364,7 +1364,7 @@ public class Index implements Comparable<Index> {
 
       // read the rowId
       int page = ByteUtil.get3ByteInt(buffer, ByteOrder.BIG_ENDIAN);
-      int row = ByteUtil.toUnsignedInt(buffer.get());
+      int row = ByteUtil.getUnsignedByte(buffer);
       
       _rowId = new RowId(page, row);
       _type = EntryType.NORMAL;
diff --git a/src/java/com/healthmarketscience/jackcess/Table.java b/src/java/com/healthmarketscience/jackcess/Table.java
index b87698e..8d09f8b 100644
--- a/src/java/com/healthmarketscience/jackcess/Table.java
+++ b/src/java/com/healthmarketscience/jackcess/Table.java
@@ -580,7 +580,7 @@ public class Table
       
         // Overflow page.  the "row" data in the current page points to
         // another page/row
-        int overflowRowNum = ByteUtil.toUnsignedInt(rowBuffer.get(rowStart));
+        int overflowRowNum = ByteUtil.getUnsignedByte(rowBuffer, rowStart);
         int overflowPageNum = ByteUtil.get3ByteInt(rowBuffer, rowStart + 1);
         rowBuffer = rowState.setOverflowRow(
             new RowId(overflowPageNum, overflowRowNum));
@@ -915,12 +915,12 @@ public class Table
     _indexSlotCount = tableBuffer.getInt(getFormat().OFFSET_NUM_INDEX_SLOTS);
     _indexCount = tableBuffer.getInt(getFormat().OFFSET_NUM_INDEXES);
 
-    int rowNum = ByteUtil.toUnsignedInt(
-        tableBuffer.get(getFormat().OFFSET_OWNED_PAGES));
+    int rowNum = ByteUtil.getUnsignedByte(
+        tableBuffer, getFormat().OFFSET_OWNED_PAGES);
     int pageNum = ByteUtil.get3ByteInt(tableBuffer, getFormat().OFFSET_OWNED_PAGES + 1);
     _ownedPages = UsageMap.read(getDatabase(), pageNum, rowNum, false);
-    rowNum = ByteUtil.toUnsignedInt(
-        tableBuffer.get(getFormat().OFFSET_FREE_SPACE_PAGES));
+    rowNum = ByteUtil.getUnsignedByte(
+        tableBuffer, getFormat().OFFSET_FREE_SPACE_PAGES);
     pageNum = ByteUtil.get3ByteInt(tableBuffer, getFormat().OFFSET_FREE_SPACE_PAGES + 1);
     _freeSpacePages = UsageMap.read(getDatabase(), pageNum, rowNum, false);
     
@@ -1340,7 +1340,7 @@ public class Table
         Object obj = iter.next();
         if (obj instanceof byte[]) {
           byte[] b = (byte[]) obj;
-          rtn.append(ByteUtil.toHexString(ByteBuffer.wrap(b), b.length));
+          rtn.append(ByteUtil.toHexString(b));
           //This block can be used to easily dump a binary column to a file
           /*java.io.File f = java.io.File.createTempFile("ole", ".bin");
             java.io.FileOutputStream out = new java.io.FileOutputStream(f);