Crunch CRN

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CRN

• Format Type : Image / Texture
  
• Endian Order : Big Endian
  
• Signature : Hx
  

Format Specifications

// crn texture header (big endian) - 74 bytes
2 bytes (char) - signature // "Hx"
2 bytes (uint16) - header size   // e.g. 106 
2 bytes (uint16) - header CRC16 
4 bytes (uint32) - data size  
2 bytes (uint16) - data CRC16
2 bytes (uint16) - width
2 bytes (uint16) - height
1 byte (uint8) - mipmap level index // 0 is the largest/first level
1 byte (uint8) - number of faces
1 byte (uint8) - format number
2 bytes (uint16) - flags
4 bytes (uint32) - reserved
4 bytes (uint32) - user data 0
4 bytes (uint32) - user data 1

8 bytes - color endpoints (palette structure)
8 bytes - color selectors (palette structure)
8 bytes - alpha endpoints (palette structure)
8 bytes - alpha selectors (palette structure)

2 bytes (uint16) - tables size
3 bytes - tables offsets
4 bytes - levels offsets


x bytes - compressed image data

Related Structures

// Palette structure

3 bytes - offsets
3 bytes - size
2 bytes - num

CRC calculation

• CRC16 calculation can be described as below:
  

// header crc16
const uint32 header_crc = crc16(&pHeader->m_data_size, (uint32)(pHeader->m_header_size - ((const uint8*)&pHeader->m_data_size - (const uint8*)pHeader)));

//data crc16
const uint32 data_crc = crc16((const uint8*)pData + pHeader->m_header_size, pHeader->m_data_size - pHeader->m_header_size);

// Note: More details in "crn_decomp.h" file.

MultiEx BMS Script

Not written yet.

Notes and Comments

• This file format occurs in games using crunch library.

Games

List of games using this file format:

• Star Stable Online (uses modified CRN file with extra header)

Compatible Programs

• crunch
• crunch_unity (special crunch version compiled for Unity games)