| ??? 12/03/04 00:09 Read: times |
#82440 - RE: Irrelevant Responding to: ???'s previous message |
Andy Neil said:
I said:
All the compiler knows about is the 8051 instruction set - the hardware beyond the chip is entirely irrelevant to the compiler! Sasha Jevtic said:
examples include multiple data pointers and expanded address spaces. But all of this is pureley internal to the chip - it has absolutely nothing whatsoever to do with the external hardware on any specific development board or other assembly. Yes, I agree entirely. Sorry; I misinterpreted what you said. My only point was that generation of code that utilizes some special features found in derivatives requires compiler awareness. In fact, multiple DPTRs are usually implemented by adding a "DPTR select" SFR - so there is no change to the instruction set at all for that. The fact that there is no instruction set modification is nice, and admittedly keeps things clean, potentially at the expense of a little bit of performance. Still, regardless of how DPTR selection is implemented in hardware, the compiler requires knowledge of it so that it can generate accesses to the appropriate DPTR, whatever the mechanism for it is. Of course, expanded memory addressing (ie, >64K) is a fundamental change to the architecture - so it must require a change to the instruction set. Absolutely. Sasha Jevtic said:
Of course, it is also convenient (although not necessary) for a compiler to include header files with SFR definitions for the derivatives you will be using. Header files are just source code - they aren't really anything to do with the compiler itself. Of course, compiler vendors like to throw them in so that you get the impression that they're "adding value" - but it's nothing you couldn't write yourself. Very true; it is a nice value-add both as a busywork saver and bug preventer. --Sasha Jevtic |
| Topic | Author | Date |
| Dunfield C Cmplr and TECEL's P500 Board | 01/01/70 00:00 | |
| largely irrelevant | 01/01/70 00:00 | |
| RE: largely irrelevant | 01/01/70 00:00 | |
| Irrelevant | 01/01/70 00:00 | |
RE: Irrelevant | 01/01/70 00:00 |