///<summary>
/// encode MIO0 header from struct
///</summary>
public static void encode_header(byte[] buf, ref MIO0_Header head)
{
write_u32_be(buf, 0x4D494F30, 0); // write "MIO0" at start of buffer
write_u32_be(buf, head.dest_size, 4);
write_u32_be(buf, head.comp_offset, 8);
write_u32_be(buf, head.uncomp_offset, 12);
}
///<summary>
/// decode MIO0 data<para/>
/// mio0_buf: buffer containing MIO0 data<para/>
/// returns the raw data as a byte array
///</summary>
public static byte[] mio0_decode(byte[] mio0_buf)
{
MIO0_Header head = new MIO0_Header();
uint bytes_written = 0;
int bit_idx = 0;
int comp_idx = 0;
int uncomp_idx = 0;
bool valid;
// extract header
valid = decode_header(mio0_buf, ref head);
// verify MIO0 header
if (!valid)
{
return(null);
}
if (!head.big_endian)
{
return(null);
}
byte[] decoded = new byte[head.dest_size];
// decode data
while (bytes_written < head.dest_size)
{
if (GET_BIT(mio0_buf, MIO0_HEADER_LENGTH, bit_idx) > 0)
{
// 1 - pull uncompressed data
decoded[bytes_written] = mio0_buf[head.uncomp_offset + uncomp_idx];
bytes_written++;
uncomp_idx++;
}
else
{
// 0 - read compressed data
byte a = mio0_buf[head.comp_offset + comp_idx + 0];
byte b = mio0_buf[head.comp_offset + comp_idx + 1];
comp_idx += 2;
int length = ((a & 0xF0) >> 4) + 3;
int idx = ((a & 0x0F) << 8) + b + 1;
for (int i = 0; i < length; i++)
{
decoded[bytes_written] = decoded[bytes_written - idx];
bytes_written++;
}
}
bit_idx++;
}
return(decoded);
}
///<summary>
/// decode MIO0 header<para/>
/// returns true if valid header, false otherwise
///</summary>
public static bool decode_header(byte[] buf, ref MIO0_Header head)
{
byte[] mio0_ascii_be = new byte[] { 0x4D, 0x49, 0x4F, 0x30 };
byte[] mio0_ascii_le = new byte[] { 0x49, 0x4D, 0x30, 0x4F };
if (compareByteArrays(buf, mio0_ascii_be, 4))
{
head.dest_size = read_u32_be(buf, 4);
head.comp_offset = read_u32_be(buf, 8);
head.uncomp_offset = read_u32_be(buf, 12);
head.big_endian = true;
return(true);
}
else if (compareByteArrays(buf, mio0_ascii_le, 4))
{
head.dest_size = read_u32_le(buf, 4);
head.comp_offset = read_u32_le(buf, 8);
head.uncomp_offset = read_u32_le(buf, 12);
head.big_endian = false;
return(true);
}
return(false);
}
