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The 3DSX format is an executable file-format designed for homebrew applications on the 3DS.

The file is structured like this:

  • Header
  • Extended Header, if the header size field is greater than 32.
  • Code relocation table header
  • Rodata relocation table header
  • Data relocation table header
  • Code segment
  • Rodata segment
  • Data segment
  • Code relocation table
  • Rodata relocation table
  • Data relocation table
  • SMDH data, if there is an extended header.
  • RomFS data, if there is an extended header.

Header

Offset Size Description
0x0 4 Magic (3DSX)
0x4 2 Header size
0x6 2 Relocation Header size
0x8 4 Format version
0xC 4 Flags
0x10 4 Code segment size
0x14 4 Rodata segment size
0x18 4 Data segment size (including bss)
0x1C 4 Bss segment size

Extended Header

Offset Size Description
0x0 4 SMDH offset
0x4 4 SMDH size
0x8 4 RomFS offset

Relocation Header

Offset Size Description
0x0 4 Number of absolute relocations
0x4 4 Number of relative relocations

Relocation

Offset Size Description
0x0 2 Number of words to skip
0x2 2 Number of words to patch