参考一下这个。
CALL/CALLR and RET must be used only in the same section. The effective address for the
CALL/RET is used as an offset to the current PCE register value. For the JP, the effective
address 16 or 17-bit (for indexed addressing) long, is added to the current PCE value. In
order to reach any address in the program space, the JPF jump and CALLF call instructions
are provided with a three byte extended addressing mode while the RETF pops also three
bytes from the stack.
As the memory space is linear, sections can be crossed by two CPU actions: next
instruction byte fetch (PC+1), relative jumps and, in some cases, by JP (for indexed
addressing mode).
Note: For safe memory usage, a function which crosses sections MUST:
- be called by a CALLF
- include only far instructions for code operation (CALLF & JPF)
All label pointers are located in section 0 (JP [ptr.w] example: ptr.w is located in section 0
and the jump address in current section)
Any illegal op-code read from the program space
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