/// <summary>
/// Adds, updates, or removes a map entry.
/// </summary>
/// <param name="offset">File offset at which the address changes.</param>
/// <param name="addr">24-bit address.</param>
public void Set(int offset, int addr)
{
Debug.Assert(offset >= 0);
if (addr == -1)
{
if (offset != 0) // ignore attempts to remove entry at offset zero
{
Remove(offset);
}
return;
}
Debug.Assert(addr >= 0 && addr < 0x01000000); // 24-bit address space
int i;
for (i = 0; i < mAddrList.Count; i++)
{
AddressMapEntry ad = mAddrList[i];
if (ad.Offset == offset)
{
// update existing
ad.Addr = addr;
mAddrList[i] = ad;
return;
}
else if (ad.Offset > offset)
{
// The i'th entry is one past the interesting part.
break;
}
}
// Carve a chunk out of the previous entry.
AddressMapEntry prev = mAddrList[i - 1];
int prevOldLen = prev.Length;
int prevNewLen = offset - prev.Offset;
prev.Length = prevNewLen;
mAddrList[i - 1] = prev;
mAddrList.Insert(i,
new AddressMapEntry(offset, addr, prevOldLen - prevNewLen));
DebugValidate();
}
/// <summary>
/// Internal consistency checks.
/// </summary>
private void DebugValidate()
{
if (mAddrList.Count < 1)
{
throw new Exception("AddressMap: empty");
}
if (mAddrList[0].Offset != 0)
{
throw new Exception("AddressMap: bad offset 0");
}
if (mAddrList.Count == 1)
{
if (mAddrList[0].Length != mTotalLength)
{
throw new Exception("AddressMap: single entry len bad");
}
}
else
{
int totalLen = 0;
for (int i = 0; i < mAddrList.Count; i++)
{
AddressMapEntry ent = mAddrList[i];
if (i != 0)
{
if (ent.Offset != mAddrList[i - 1].Offset + mAddrList[i - 1].Length)
{
throw new Exception("Bad offset step to " + i);
}
}
totalLen += ent.Length;
}
if (totalLen != mTotalLength)
{
throw new Exception("AddressMap: bad length sum (" + totalLen + " vs " +
mTotalLength + ")");
}
}
}
/// <summary>
/// Removes an entry from the set.
/// </summary>
/// <param name="offset">The initial offset of the mapping to remove. This
/// must be the initial value, not a mid-range value.</param>
/// <returns>True if something was removed.</returns>
public bool Remove(int offset)
{
if (offset == 0)
{
throw new Exception("Not allowed to remove entry 0");
}
for (int i = 1; i < mAddrList.Count; i++)
{
if (mAddrList[i].Offset == offset)
{
// Add the length to the previous entry.
AddressMapEntry prev = mAddrList[i - 1];
prev.Length += mAddrList[i].Length;
mAddrList[i - 1] = prev;
mAddrList.RemoveAt(i);
DebugValidate();
return(true);
}
}
return(false);
}
// Copy constructor.
public AddressMapEntry(AddressMapEntry src)
{
Offset = src.Offset;
Addr = src.Addr;
Length = src.Length;
}