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How much more efficient is assembly code versus C in terms of clock cycles?

Catwell
My current PIC projects are getting more complicated to the point where I am thinking C might be needed. A side note: most jobs I've had, I ended up using assembly on all the projects due most to my adamant grandstanding of code efficiency of the base language. I was able to get away with this posture for a long time. However, I am now doing complex math on the PIC that I don't want to figure out a clever bit manipulation to solve. EX: Dividing a 16bit number by another using 8bit registers.

The PICs I am working on have limited (1Mhz to 4Mhz clock) cycles, and I am wondering if C is going to waste a substantial amount of time executing. Has anyone ever had experience with both and could share some thoughts on the comparison?

 

 

C

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    You can't put numbers on it easily but well tuned assembler will usually outperform C for speed or code size or even both. However you should remmeber that the algorithm is often much more significant - for example a ripple sort in assembler will be nowhere near as fast as a quick sort in C.

     

    C outperforms assembler (in my experience at least 10:1) in terms of time to write/test/sign off code.

     

    Your best bet is almost always to write the application in C and use assembler for the bits you need to improve (this can be less true with very limited processors like the the original architecture 8 bit PICs).

     

    You do not need to write your own maths routines in assembler unless you want - a million people have doen it already:

     

    http://www.piclist.com/techref/microchip/math/div/index.htm

     

    (just one example - there are many).

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  • 0

    You can't put numbers on it easily but well tuned assembler will usually outperform C for speed or code size or even both. However you should remmeber that the algorithm is often much more significant - for example a ripple sort in assembler will be nowhere near as fast as a quick sort in C.

     

    C outperforms assembler (in my experience at least 10:1) in terms of time to write/test/sign off code.

     

    Your best bet is almost always to write the application in C and use assembler for the bits you need to improve (this can be less true with very limited processors like the the original architecture 8 bit PICs).

     

    You do not need to write your own maths routines in assembler unless you want - a million people have doen it already:

     

    http://www.piclist.com/techref/microchip/math/div/index.htm

     

    (just one example - there are many).

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