Chunks are the highest level data containers in NSF files. Each chunk is 64kb (0x10000 bytes) in size, in congruence with the 64kb pages allocated to contain them.
Format
Uncompressed chunks
Non-texture chunks
| Offset
|
Field
|
Size
|
Value
|
| 0x0
|
Magic Number
|
2 bytes
|
0x1234
|
| 0x2
|
Type
|
2 bytes
|
!=1
|
| 0x4
|
ID
|
4 bytes
|
*
|
| 0x8
|
Entry Count
|
4 bytes
|
c
|
| 0xC
|
Checksum
|
4 bytes
|
*
|
| 0x10
|
Entry Offsets
|
4 x c bytes
|
*
|
| 0x10 + (4 x c)
|
Entries
|
* x c bytes
|
*
|
Texture chunks
| Offset
|
Field
|
Size
|
Value
|
| 0x0
|
Magic Number
|
2 bytes
|
0x1234
|
| 0x2
|
Type
|
2 bytes
|
1
|
| 0x4
|
Texture Page EID
|
4 bytes
|
*
|
| 0x8
|
Tex. Page Entry Type
|
4 bytes
|
5
|
| 0xC
|
Checksum
|
4 bytes
|
*
|
| 0x10
|
Texture data
|
0xFFF0/65520 bytes
|
*
|
Compressed chunks
| Offset
|
Field
|
Size
|
Value
|
| 0x0
|
Magic Number
|
2 bytes
|
0x1235
|
| 0x2
|
Unused
|
2 bytes
|
*
|
| 0x4
|
Length
|
4 bytes
|
l
|
| 0x8
|
Skip
|
4 bytes
|
s
|
| 0xC
|
Compressed data
|
n bytes
|
*
|
| 0xC+n
|
Skipped data
|
s bytes
|
*
|
| 0xC+n+s
|
Uncompressed data
|
(0x10000 - l) bytes
|
*
|
Types
| Type
|
Name
|
| 0
|
Normal Chunk
|
| 1
|
Texture Chunk
|
| 2
|
Prototype Sound Chunk
|
| 3
|
Sound Chunk
|
| 4
|
Wavebank Chunk
|
| 5
|
Speech Chunk
|
Chunk IDs/CIDs
Each chunk also has its own unique ID: chunk IDs have been assigned according to their sequence in the NSF file; the formula for a Chunk ID (referred to throughout this guide as CID) is: '(index << 1) - 1' or the sequence of odd numbers (which have have their LSB set). The reason for this will be explained shortly. **Texture chunks do NOT have their associated precomputed Chunk ID in the CID field-it is to be computed later.
