// attrData, index (stride count), and length (in words) are provided by the caller
public Section(Modbus MB, AttrData BaseAttr, int index, int Len, bool load)
{
this.MB = MB; // Save Modbus I/O object
this.attr = (T)(object)BaseAttr.Val; // Reverse lookup AttrData => Attr
this.Index = index; // For repeated structures
this.BaseAttr = BaseAttr; // Need the stride for indexing
this.Len = Len; // Save for section write message
this.Load = load; // False => already already cleared to 0's
byte[] t; // Used in case I/O fails
string idx = string.Empty;
if (BaseAttr.Count > 1)
{
idx = $"[{index}]";
}
MB.LogIt($"\nAllocating Section {MB.GetAttributeName(BaseAttr.Class, BaseAttr.Val)}{idx} Length = {Len}, PreLoad = {load}");
if (load) // Load if previous contents needed
{
b = new byte[Len * 2]; // Big enough for all reads
if (Len <= MaxWordSize) // If only one read needed, read it directly
{
t = MB.GetAttributeBlock(BaseAttr, index, Len); //
Buffer.BlockCopy(t, 0, b, 0, t.Length); // save away the bytes
}
else // Otherwise, read it in block size chunks
{
int wordsRead = 0; // Words read so far
int wordsToRead = Len; // Words needed
while (wordsToRead > 0) // Until all have been read
{
t = MB.GetAttributeBlock(BaseAttr, index, Math.Min(wordsToRead, MaxWordSize), wordsRead);
Buffer.BlockCopy(t, 0, b, wordsRead * 2, t.Length); // save away the bytes
wordsRead += MaxWordSize; // Update words read
wordsToRead -= MaxWordSize; // Update words remaining (OK if it goes negative)
}
}
}
else
{
b = new byte[Len * 2]; // Empty array big enough for all data
}
}
