| ??? 06/14/11 06:21 Read: times |
#182648 - RE: optimize LJMPs to AJMPs, etc Responding to: ???'s previous message |
Maarten Brock said:
10. AJMP/ACALL is only relevant on 2kB limited devices IMHO, otherwise they just use up expensive instructions
Jan Waclawek said:
I think Keil's assembler knows to optimize LJMPs to AJMPs where possible The Keil Assembler has CALL and JMP "generic" mnemonics: Keil Ax51 Manual said:
CALL JMP
Generic jumps and calls are two instruction mnemonics that do not represent a specific opcode: JMP may assemble to SJMP, AJMP, LJMP or EJMP; CALL may assemble to ACALL, LCALL or ECALL. These generic mnemonics always evaluate to an instruction, not necessarily the shortest, that will reach the specified program address operand. http://www.keil.com/support/m...ddress.htm For the Keil C51 Compiler, the ROM directive controls which Jump & Call instructions are used: Keil C51 Manual said:
You use the ROM directive to specify the size of the program memory. This directive affects the coding of the JMP and CALL instructions.
http://www.keil.com/support/m...51_rom.htm |
| Topic | Author | Date |
| 8051 core quiz | 01/01/70 00:00 | |
| quizes are out of fashion these days... | 01/01/70 00:00 | |
| I did it.... | 01/01/70 00:00 | |
| thanks | 01/01/70 00:00 | |
| missed CJNE | 01/01/70 00:00 | |
| indeed | 01/01/70 00:00 | |
| I guess a quite frequent oversight | 01/01/70 00:00 | |
| RE: optimize LJMPs to AJMPs, etc | 01/01/70 00:00 | |
| Maybe? | 01/01/70 00:00 | |
| caught again! | 01/01/70 00:00 | |
| Most common 8051 assembly mistake? | 01/01/70 00:00 | |
| Not just 8051? | 01/01/70 00:00 | |
| Different assemblers have different probabilities | 01/01/70 00:00 | |
| Conceptual & Typographical errors | 01/01/70 00:00 | |
| some assemblers do | 01/01/70 00:00 | |
| Readability helps | 01/01/70 00:00 | |
99's | 01/01/70 00:00 |