internal static string DecodeZString(Queue<byte> zBytes, IZMemory z_memory)
{
var sb = new StringBuilder();
int currentAlphabet = 0;
int lockAlphabet = 0;
char c, c2, c3;
int abbrevAddr = 0;
while (zBytes.Count > 0)
{
c = (char)zBytes.Dequeue();
switch ((int)c)
{
case 1:
case 2:
case 3:
// Abbreviation in V2+
if (zBytes.Count == 0) // This is all we're getting.
break;
c2 = (char)zBytes.Dequeue();
abbrevAddr = z_memory.GetWord(z_memory.Header.AbbreviationTableLocation + (((((int)c) - 1) * 32 + ((int)c2)) * 2));
abbrevAddr *= 2; // Word address
sb.Append(PrintZString(z_memory, abbrevAddr));
break;
case 4: // Always a shift up
if (currentAlphabet == 2)
currentAlphabet = 0;
else
currentAlphabet++;
break;
case 5: // Always a shift down
if (currentAlphabet == 0)
currentAlphabet = 2;
else if (currentAlphabet == 2)
currentAlphabet = 1;
else
currentAlphabet = 0;
break;
case 6: // Literal output character if alphabet is P.
if (currentAlphabet == 2)
{
if (zBytes.Count == 0)
break;
c2 = (char)zBytes.Dequeue();
if (zBytes.Count == 0)
break;
c3 = (char)zBytes.Dequeue();
int w = ((((int)c2 << 5) & 0x03e0) | ((int)c3 & 0x1f));
sb.Append((char)w);
currentAlphabet = lockAlphabet;
}
else
{
sb.Append(Alpha[currentAlphabet][(int)c]);
currentAlphabet = lockAlphabet;
}
break;
default:
sb.Append(Alpha[currentAlphabet][(int)c]);
currentAlphabet = lockAlphabet;
break;
}
}
// We're done!
return sb.ToString();
}
internal static string PrintZString(IZMemory z_memory, int addr)
{
int tmp = 0;
Queue<byte> zBytes = new Queue<byte>();
while ((tmp & 0x8000) == 0)
{
tmp = z_memory.GetWord(addr);
addr += 2;
zBytes.Enqueue((byte)((tmp >> 10) & 0x1f));
zBytes.Enqueue((byte)((tmp >> 5) & 0x1f));
zBytes.Enqueue((byte)(tmp & 0x1f));
}
string ret = ZMachine.Common.ZText.DecodeZString(zBytes, z_memory);
zBytes = null;
return ret;
}