NSO (File Format)

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NSO is a file format used on the Nintendo Switch for storing executable code. All Switch game store code as NSO files.

File Format

Header

The file starts with a header. It has the following structure.

Offset	Type	Description
0x00	Char[4]	File magic. Always NSO0 in ASCII.
0x04	UInt32	Version number of the file format.
0x08	Byte[4]	Reserved.
0x0C	UInt32	Flag. xxxx xxxx xxxx xxxx xxxx xxxx xxAB CDEF. A: verify .data hash. B: verify .rodata hash. C: verify .text hash. D: sets whether .data is compressed. E: sets whether ..rodata is compressed. F: sets whether text is compressed.
0x10	UInt32	.text section offset.
0x14	UInt32	.text memory offset.
0x18	UInt32	.text decomopressed size in bytes.
0x1C	UInt32	Module offset.
0x20	UInt32	.rodata section offset.
0x24	UInt32	.rodata memory offset.
0x28	UInt32	.rodata decomopressed size in bytes.
0x2C	UInt32	Module size in bytes.
0x30	UInt32	.data section offset.
0x34	UInt32	.data memory offset.
0x38	UInt32	.data decomopressed size in bytes.
0x3C	UInt32	.bss size.
0x40	Byte[0x20]	Build ID. Identical to .note section from an ELF.
0x60	UInt32	.text compressed size in bytes.
0x64	UInt32	.rodata compressed size in bytes.
0x68	UInt32	.data compressed size in bytes.
0x6C	Byte[0x1C]	Padding.
0x88	UInt32	API .rodata region offset.
0x8C	UInt32	API .rodata region size in bytes.
0x90	UInt32	Dynstr .rodata region offset.
0x94	UInt32	Dynstr .rodata region size in bytes.
0x98	UInt32	Dynsym .rodata region offset.
0x9C	UInt32	Dynsym .rodata region size in bytes.
0xA0	Byte[0x20]	.text decompressed data SHA-256 hash
0xC0	Byte[0x20]	.rodata decompressed data SHA-256 hash
0xE0	Byte[0x20]	.data decompressed data SHA-256 hash

Tools

The following tools can handle NSO files:

• (none)