| ??? 05/19/12 07:48 Read: times Msg Score: +1 +1 Good Answer/Helpful |
#187429 - Separate "the C view of program" from "microcontroller view" Responding to: ???'s previous message |
Yagnesh Mehta said:
You told me that its depends on compiler but is there any common ANSWER?
The concept with TEXT, DATA, BSS is used by unix compilers, but are well-established terms. But the terms only discuss type of information - not what physical storage media that will be used. For a PC, everything will get into RAM. For a microcontroller, TEXT would normally go to flash. But could just as well go to RAM. Bigger microcontrollers runs all code in RAM just for maximum speed. But not all microcontrollers can run code from RAM. For a microcontroller DATA and BSS goes into RAM. But a microcontroller can have multiple RAM regions. Sometimes using same addressing modes so the regions are just like multiple memories with different start address. Sometimes using completely different addressing modes - so the regions can all start from address zero and the used processor instruction decides which of the regions that is addressed. But DATA and BSS can end up in DATA, XDATA, ... And const variables can be moved into CODE. Next thing - CODE here doesn't mean flash. It just means that the 8051 needs to use the specific processor instructions that addresses the CODE memory space. The normal instruction fetching, jumps etc always uses this address space. But it is possible for some 8051 chips to map RAM into this address space. So CODE can contain both ROM and RAM. So there are two completely different sets of class names that can be used. One based around the C standard view of a program. And one based around the processor view of the program. |
| Topic | Author | Date |
| Memory Organization | 01/01/70 00:00 | |
| Tried any good C book lately? | 01/01/70 00:00 | |
| I am using Dennis Ritchie_ANCI C | 01/01/70 00:00 | |
| Variables don't move just because you assign to them | 01/01/70 00:00 | |
| can we start from ZERO........ | 01/01/70 00:00 | |
| Have you read my original post? | 01/01/70 00:00 | |
| mixing stuff | 01/01/70 00:00 | |
| where it will be for MCU? | 01/01/70 00:00 | |
| is there any book for this fundamental things? | 01/01/70 00:00 | |
| and .... | 01/01/70 00:00 | |
| In this a general or Specific Question | 01/01/70 00:00 | |
| its General Que ???? | 01/01/70 00:00 | |
| Separate "the C view of program" from "microcontroller view" | 01/01/70 00:00 | |
| NO! | 01/01/70 00:00 | |
| why not?? | 01/01/70 00:00 | |
| No - generic isn't meaningful | 01/01/70 00:00 | |
| Interview questions can be asked out of limited knowledge | 01/01/70 00:00 | |
Seldom "one" answer other than to trivial questions | 01/01/70 00:00 | |
| In Addition | 01/01/70 00:00 | |
| Embedded? | 01/01/70 00:00 | |
| sometimes, usually | 01/01/70 00:00 |