Object Code Translation
MPE documents | |
 Complete PDF | |
| Table of Contents | |
| Index | |
| E0201 Edition 4 ♥ | |
| E0300 Edition 3 | |
| E0692 Edition 3 |
Original CM
Object Code
Translated
Into
CM Instructions NM Instructions
| | | |
+-------------+ ---------> +-------------+
| Orig | | |
| CM | | Translated |
| Section | | NM |
+-------------+ ----+ | Section |
| | |
| | |
+----> +-------------+
| |
Each CM object code instruction may expand to several NM instructions
during translation, but the total translated section requires fewer
NM instructions than would be used to emulate the original object code.
The CM emulator updates CM registers (such as STATUS) during
the emulation of every single instruction. The OCT may recognize
that the STATUS register is not accessed by a sequence of object
code, and so ignore updating the STATUS register until later, when
it is actually referenced. Performance is improved because unnecessary
emulator cycles are saved.
It is important to understand, however, that during the execution
of the resulting NM section of code, the actual MITROC bit values
in the CM STATUS register may be undefined or incorrect in the middle
of the section.
Only at the beginning of each section is the CM state known to be correct.
These "safe" boundaries, between sections, are called node points.
|
Debugging Emulated CM Code |
Node Points in Translated Code |