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Message: <blockquote data-quote="Wiimm" data-source="post: 2711678" data-attributes="member: 191758">CISO file formatI have analyzed the CISO format by studying the source code of uLoader. Here I will explain the results and hope that anyone can confirm them.Data Structure[code]enum // some constants{CISO_HEAD_SIZE       = 0x8000,             // total header sizeCISO_MAP_SIZE        = CISO_HEAD_SIZE - 8, // map sizeCISO_MIN_BLOCK_SIZE  = WII_SECTOR_SIZE,    // minimal allowed block size};typedef struct CISO_Head_t{u8  magic[4];            // "CISO"u32 block_size;          // stored as litte endian (not network byte order)u8  map[CISO_MAP_SIZE];  // 0=unused, 1=used, others=invalid} __attribute__ ((packed)) CISO_Head_t;[/code]Each CISO file has a header with 32 KiB (32768 bytes). The first 4 bytes are the magic "CISO". The next 4 bytes are a 4 byte integer stored in little endian (intel format but not network byte order).The MAPThe map uses the rest of the head (32760 bytes). Each byte represents a ISO block with given block size. A '1' means that the block is stored in the file, a '0' means that it is not stored (and is logical filled with zeros).If reading from a CISO it is good to transform the map into a other map:CODE  typedef u16 CISO_Map_t;const CISO_Map_t CISO_UNUSED_BLOCK = (CISO_Map_t)~0;CISO_Head_t * head = ...CISO_Map_t ciso_map[CISO_MAP_SIZE];CISO_Map_t count = 0;int idx;for ( idx = 0; idx < CISO_MAP_SIZE; idx++ )ciso_map[idx] = head->map[idx] ? count++ : CISO_UNUSED_BLOCK;Reading a byte from the CISO file looks like this:[code]u8 ReadByteCISO ( ... file, CISO_Map_t * ciso_map, u32 block_size, off_t iso_off ){const u32 block = iso_off/block_size;if ( block >= CISO_MAP_SIZE || ciso_map[block] == CISO_UNUSED_BLOCK )return 0;// calcualte the base addressu32 file_off = ciso_map[block] * (u64)block_size + CISO_UNUSED_BLOCK;// add the offset inside the blockfile_off += iso_off - block * (u64)block_size;return ReadByte(file,file_off);}[/code]Good block_sizeIt seems that block_size must be a multiple of WII_SECTOR_SIZE (= 32 KiB = 32768).To store a complete Wii disc with 4 699 979 776 bytes the block size must be at least 5*32=160 KiB and for double layer 320 KiB.When extracting a disc from WBFS the uLoader software uses the WBFS sector size (multiple of 2 MiB) as CISO block size. The 'isotociso' tool (part of uLoader source)  uses a fixed block size of 4 MiB. These block sizes are much larger and the ciso files grow a litle bit.My Questions: <ul> <li data-xf-list-type="ul"> Is the block size always a multiple of 32768 (32 KiB)?</li> <li data-xf-list-type="ul"> Must the block size be a power 2?</li> <li data-xf-list-type="ul"> Is there a importand minimal CISO block size?</li> <li data-xf-list-type="ul"> Does a USB loader need a max block limitation to limit the size of the internal mapping table?</li> </ul>wwt + witI have implemented CISO support into my <a href="http://wiimm.de/wwt/" target="_blank">WWT tools</a>.If writing the block size is at least 1 MiB, but the maximum used block number never exceeds  8192.If reading a CISO plausibility checks are done to verify a valid CISO: <ul> <li data-xf-list-type="ul"> The magic must be "CISO".</li> <li data-xf-list-type="ul"> The block size must be a multiple of 32 KiB.</li> <li data-xf-list-type="ul"> No other values than 0 and 1 are allowed for the map.</li> <li data-xf-list-type="ul"> The filesize must be correspondent to the number of used blocks.</li> </ul>My Question: <ul> <li data-xf-list-type="ul"> Are other values than 0 and 1 allowed for the map?</li> </ul></blockquote>

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