static int read_itcompr16(ITPACK status, ModuleReader reader, short[] buffer, ushort count, ref ushort incnt)
{
int x, y, needbits, havebits, new_count = 0;
ushort bits = status.bits;
ushort bufbits = status.bufbits;
short last = status.last;
byte buf = status.buf;
int place = 0;
while (place < count)
{
needbits = new_count != 0 ? 4 : bits;
x = havebits = 0;
while (needbits != 0)
{
/* feed buffer */
if (bufbits == 0)
{
if (incnt-- > 0)
{
// Turns out the normal mikmod implementation just sorta ignores EOF when reading samples...
// so in this situation I've changed the mikMod test application to fail in these situations
// and going to get sharpMik todo the same.
buf = reader.Read_byte();
if (reader.isEOF())
{
throw new Exception("EOF while reading the samples!");
}
}
else
{
buf = 0;
}
bufbits = 8;
}
/* get as many bits as necessary */
y = needbits < bufbits ? needbits : bufbits;
x |= (buf & ((1 << y) - 1)) << havebits;
buf >>= y;
bufbits = (ushort)(bufbits - (ushort)y);
needbits -= y;
havebits += y;
}
if (new_count != 0)
{
new_count = 0;
if (++x >= bits)
{
x++;
}
bits = (ushort)x;
continue;
}
if (bits < 7)
{
if (x == (1 << (bits - 1)))
{
new_count = 1;
continue;
}
}
else if (bits < 17)
{
y = (0xffff >> (17 - bits)) - 8;
if ((x > y) && (x <= y + 16))
{
if ((x -= y) >= bits)
{
x++;
}
bits = (ushort)(x);
continue;
}
}
else if (bits < 18)
{
if (x >= 0x10000)
{
bits = (ushort)(x - 0x10000 + 1);
continue;
}
}
else
{
/* error in compressed data... */
throw new Exception("Invalid data");
}
if (bits < 16) /* extend sign */
{
x = ((short)(x << (16 - bits))) >> (16 - bits);
}
buffer[place++] = (last += (short)x);
}
status.bits = bits;
status.bufbits = bufbits;
status.last = last;
status.buf = buf;
return(place);
}
static int read_itcompr8(ITPACK status, ModuleReader reader, short[] buffer, ushort count, ref ushort incnt)
{
ushort x;
int y, needbits, havebits, new_count = 0;
ushort bits = status.bits;
ushort bufbits = status.bufbits;
sbyte last = (sbyte)status.last;
byte buf = status.buf;
int place = 0;
while (place < count)
{
needbits = (new_count != 0 ? 3 : bits);
x = 0;
havebits = 0;
while (needbits != 0)
{
/* feed buffer */
if (bufbits == 0)
{
if (incnt-- > 0)
{
buf = reader.Read_byte();
}
else
{
buf = 0;
}
bufbits = 8;
}
/* get as many bits as necessary */
y = needbits < bufbits ? needbits : bufbits;
x |= (ushort)((buf & ((1 << y) - 1)) << havebits);
buf >>= y;
bufbits -= (ushort)y;
needbits -= y;
havebits += y;
}
if (new_count != 0)
{
new_count = 0;
if (++x >= bits)
{
x++;
}
bits = (ushort)x;
continue;
}
if (bits < 7)
{
if (x == (1 << (bits - 1)))
{
new_count = 1;
continue;
}
}
else if (bits < 9)
{
y = (0xff >> (9 - bits)) - 4;
if ((x > y) && (x <= y + 8))
{
if ((x -= (ushort)y) >= bits)
{
x++;
}
bits = (ushort)x;
continue;
}
}
else if (bits < 10)
{
if (x >= 0x100)
{
bits = (ushort)(x - 0x100 + 1);
continue;
}
}
else
{
/* error in compressed data... */
throw new Exception("Invalid Data");
}
if (bits < 8) /* extend sign */
{
x = (ushort)(((sbyte)(x << (8 - bits))) >> (8 - bits));
}
short val = (short)((last += (sbyte)x) << 8);
buffer[place++] = (short)val;
}
status.bits = bits;
status.bufbits = bufbits;
status.last = last;
status.buf = buf;
return(place);
}