| ??? 03/31/08 09:00 Read: times |
#152739 - Processor doesn't just ignore instructions! Responding to: ???'s previous message |
Deep Veer said:
but here when i pop acc two times , it ignore the RET No, the processor doesn't just ignore the instruction! If the instruction has been fetched from CODE memory, it will be executed The only way to ensure that an instruction is not executed is to ensure that it is not fetched from CODE memory - eg, by having a jump around it. If you have POPped the "real" return address from the stack, then executing a RET will simply take whatever is left on the top of the stack, and use that as its return address. If you haven't taken care to ensure that this represents a valid return address then the result could be very interesting indeed... |
| Topic | Author | Date |
| call routine problem | 01/01/70 00:00 | |
| Yes, but... | 01/01/70 00:00 | |
| call routine | 01/01/70 00:00 | |
| what do you mean by "come out"? | 01/01/70 00:00 | |
| call routine | 01/01/70 00:00 | |
| Does not ignore RET but... | 01/01/70 00:00 | |
| Good implementation | 01/01/70 00:00 | |
| one of the reasons might be... | 01/01/70 00:00 | |
| call routine | 01/01/70 00:00 | |
| please explain... | 01/01/70 00:00 | |
| Two things need explaining | 01/01/70 00:00 | |
| Processor doesn't just ignore instructions! | 01/01/70 00:00 | |
| I guess ... | 01/01/70 00:00 | |
| call routine | 01/01/70 00:00 | |
use sjmp ljmp ajmp | 01/01/70 00:00 |