private static void ValidateExpectedSize(byte[] value, IAb1DataItem item)
{
int expectedSize = item.Size * item.Entry.ElementCount;
if (expectedSize != value.Length)
{
throw new InvalidItemSizeException(expectedSize, value.Length, item.Name);
}
}
/// <summary>
/// Returns the bytes containing the item value. Note that the data offset field contains the bytes starting
/// at the high-order byte of the 32 bit field.
/// </summary>
/// <param name="item"></param>
/// <returns></returns>
private static byte[] GetLocalItemValue(IAb1DataItem item)
{
var result = new byte[item.Entry.DataSize];
for (int i = 0; i < item.Entry.DataSize; i++)
{
result[i] = (byte)(item.Entry.DataOffset >> (24 - 8 * i));
}
return(result);
}
/// <summary>
/// Attempts to create a data item.
/// </summary>
/// <param name="entry"></param>
/// <returns></returns>
public static IAb1DataItem TryCreateDataItem(Ab1DirectoryEntry entry)
{
IAb1DataItem item = SupportedItems.FirstOrDefault(dataItem => dataItem.Type == entry.ElementTypeCode);
if (item == null)
{
return(null);
}
item = item.Create();
item.Entry = entry;
return(item);
}
/// <summary>
/// Returns the item value.
/// </summary>
/// <param name="item"></param>
/// <exception cref="InvalidItemSizeException">Thrown if the item size does not match the expected size.</exception>"
/// <returns></returns>
private byte[] GetItemValue(IAb1DataItem item)
{
if (item == null)
{
throw new ArgumentNullException("item");
}
//
// Based on the Ab1 specifications, if a item size is greater than 4 bytes the offset points to the data
// otherwise it contains the data.
//
byte[] result =
item.Entry.DataSize <= Constants.MaxLocalItemByteSize
? GetLocalItemValue(item)
: GetRemoteItemValue(item);
ValidateExpectedSize(result, item);
return(result);
}
/// <summary>
/// Parser data.
/// </summary>
/// <param name="context"></param>
public void ParseData(IParserContext context)
{
if (context == null)
{
throw new ArgumentNullException("context");
}
if (context.Header.MajorVersion != MajorVersion)
{
throw new InvalidFileVersionException(MajorVersion, context.Header.MajorVersion);
}
Context = context;
Context.Header.DirectoryEntries.ForEach(
entry =>
{
IAb1DataItem item = DataItemFactory.TryCreateDataItem(entry);
if (item == null)
{
return;
}
item.Accept(this);
});
}
/// <summary>
/// Retrives the matching xml tag of type and id.
/// </summary>
/// <param name="item"></param>
/// <returns></returns>
private AB_RootDataTag RetrieveTag(IAb1DataItem item)
{
return(this.tagsByType[item.Name].First(tag =>
tag.ID == item.Entry.TagNumber.ToString(CultureInfo.InvariantCulture) &&
tag.Name == item.Entry.TagName));
}
private static void ValidateExpectedSize(byte[] value, IAb1DataItem item)
{
int expectedSize = item.Size * item.Entry.ElementCount;
if (expectedSize != value.Length)
throw new InvalidItemSizeException(expectedSize, value.Length, item.Name);
}
/// <summary>
/// Returns the bytes containing the item value. Note that the data offset field contains the bytes starting
/// at the high-order byte of the 32 bit field.
/// </summary>
/// <param name="item"></param>
/// <returns></returns>
private static byte[] GetLocalItemValue(IAb1DataItem item)
{
var result = new byte[item.Entry.DataSize];
for (int i = 0; i < item.Entry.DataSize; i++)
{
result[i] = (byte)(item.Entry.DataOffset >> (24 - 8 * i));
}
return result;
}
/// <summary>
/// Returns the bytes containing the item value based on the data offset pointer and data size.
/// </summary>
/// <param name="item"></param>
/// <returns></returns>
private byte[] GetRemoteItemValue(IAb1DataItem item)
{
Context.Reader.BaseStream.Position = item.Entry.DataOffset;
byte[] result = Context.Reader.ReadBytes(item.Entry.DataSize);
return result;
}
/// <summary>
/// Returns the item value.
/// </summary>
/// <param name="item"></param>
/// <exception cref="InvalidItemSizeException">Thrown if the item size does not match the expected size.</exception>"
/// <returns></returns>
private byte[] GetItemValue(IAb1DataItem item)
{
if (item == null) throw new ArgumentNullException("item");
//
// Based on the Ab1 specifications, if a item size is greater than 4 bytes the offset points to the data
// otherwise it contains the data.
//
byte[] result =
item.Entry.DataSize <= Constants.MaxLocalItemByteSize
? GetLocalItemValue(item)
: GetRemoteItemValue(item);
ValidateExpectedSize(result, item);
return result;
}
/// <summary>
/// Returns the bytes containing the item value based on the data offset pointer and data size.
/// </summary>
/// <param name="item"></param>
/// <returns></returns>
private byte[] GetRemoteItemValue(IAb1DataItem item)
{
Context.Reader.BaseStream.Position = item.Entry.DataOffset;
byte[] result = Context.Reader.ReadBytes(item.Entry.DataSize);
return(result);
}
