Inside Macintosh: Mac OS Runtime Architectures /

Chapter 10 - Classic 68K Runtime Architecture / How 32-Bit Everything Is Implemented

Intrasegment References

If you compile and link units with any option that specifies the far model for code, any instruction that makes an intrasegment reference is generated with a 32-bit absolute address. This address is the byte offset from the beginning of the segment to the referenced entry point. The address of any instruction making such a reference is stored in compressed form in an area called segment relocation information. The modified _LoadSeg trap, using this information and the load address of the segment, relocates each such instruction by adding the load address of the segment to the instruction's 32-bit address field.