Hi, its me again ;)
Any idea how difficult it would be to add optimisation operators like '+=' and company? Here is a piece of compiled C from my project: ; .line 150; stepperirq.c MOTOR.nco += MOTOR.speed; MOVF (_g + 10), W, B ADDWF (_g + 4), W, B MOVWF r0x00 MOVF (_g + 11), W, B ADDWFC (_g + 5), W, B MOVWF r0x01 MOVF r0x00, W MOVWF (_g + 4), B MOVF r0x01, W MOVWF (_g + 5), B This look rather long compared to this snipper I copied from the web: movf a,w addwf b,f btfsc STATUS,C incf b+1,f movf a+1,w addwf b+1,f 6 versus 10 instructions and a two one byte temp vars. I have a beef with the temp vars especially as (unlike I thought before) these get overlaid with temp vars (registers really for the compiler I guess) which necessitates altogether four push/pull instructions in my critical interrupt handler. That [MOTOR.nco += MOTOR.speed] innocent looking C statement is responsible for almost about 30% of my execution time! Of course I could do this in in assembly but that would be more pain as the compiler does a nice job of simplifying the MOTOR.xxxx variable access which is a bit more complicated than it looks and if I go to assembly then I'm on my own. OTH then I could take advantage of the carry flag of this 16 bit add operation that would be useful for me and further improve my execution speed. Anyway would it be difficult to add this optimisation, in the peephole optimiser or earlier in the pipeline? Any other ideas how to optimise that piece of code? br Kusti This e-mail may contain confidential or privileged information. If you are not the intended recipient (or have received this e-mail in error) please notify the sender immediately and destroy this e-mail. Any unauthorized copying, disclosure or distribution of the material in this e-mail is strictly forbidden. We will not be liable for direct, indirect, special or consequential damages arising from alteration of the contents of this message by a third party or as a result of any virus being passed on or as of transmission of this e-mail in general. ------------------------------------------------------------------------------ Open source business process management suite built on Java and Eclipse Turn processes into business applications with Bonita BPM Community Edition Quickly connect people, data, and systems into organized workflows Winner of BOSSIE, CODIE, OW2 and Gartner awards http://p.sf.net/sfu/Bonitasoft _______________________________________________ Sdcc-user mailing list Sdcc-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/sdcc-user
