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Hot!which version of XC8 support PIC18 extended mode?

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irun2
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2020/07/03 01:25:13 (permalink)
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which version of XC8 support PIC18 extended mode?

Seems to me the XINST=ON option is not supported by XC8, I've tried XC8 v1.21, v1.45, v2.1, they all issued a message saying that extended mode is not supported.
 
 
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    Jim Nickerson
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    Re: which version of XC8 support PIC18 extended mode? 2020/07/06 09:29:52 (permalink)
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    Which specific PIC18 are you using ?
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    jtemples
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    Re: which version of XC8 support PIC18 extended mode? 2020/07/06 09:40:59 (permalink)
    +4 (4)
    Extended mode is not supported by any version of XC8.  Only C18 supports it.
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    ric
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    Re: which version of XC8 support PIC18 extended mode? 2020/07/06 13:33:12 (permalink)
    +2 (4)
    Which begs the question, WHY are you trying to activate extended mode?
    XC8 doesn't support it because they found the compiled code was less efficient with XINST on.

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    jtemples
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    Re: which version of XC8 support PIC18 extended mode? 2020/07/06 14:00:27 (permalink)
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    My theory, based on no evidence at all, is that extended mode was added in an attempt to make C18 competitive with Hi-Tech.  That failed, so they just bought Hi-Tech.
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    1and0
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    Re: which version of XC8 support PIC18 extended mode? 2020/07/06 14:21:47 (permalink)
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    So why the extended instruction set still implemented in the latest PIC18 devices? I don't use it even when programming assembly. ;)
     
     
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    RISC
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    Re: which version of XC8 support PIC18 extended mode? 2020/07/06 14:25:56 (permalink)
    +3 (3)
    Hi,
    I guess it is part of the current PIC18 core...don't change a running system Smile: Smile
    Regards

    For support make sure to check first here : http://microchipdeveloper.com
    There are hundreds of PIC, AVR, SAM...which one do YOU use ?
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    1and0
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    Re: which version of XC8 support PIC18 extended mode? 2020/07/06 15:41:24 (permalink)
    +2 (2)
    RISC
    I guess it is part of the current PIC18 core...don't change a running system

    I'm not so sure about that. ;)  The newer PIC18 devices, like K42 and Q43, removed the ADDFSR, CALLW, and SUBFSR instructions and added the MOVSFL instruction.
     
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    irun2
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    Re: which version of XC8 support PIC18 extended mode? 2020/07/06 20:25:29 (permalink)
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    JANickerson
    Which specific PIC18 are you using ?




    PIC18F44K20, just for testing purpose. I want to compare the efficiency between the standard and extended ISA, but without luck currently XC8 does not support the so-called extended instructions.
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    ric
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    Re: which version of XC8 support PIC18 extended mode? 2020/07/06 20:28:01 (permalink)
    +2 (2)
    irun2
    ... currently XC8 does not support the so-called extended instructions.

    As you may gather from the responses, almost certainly it never will.
    The HiTech programmers were able to get better performance from the standard instruction set.
    Switching to extended mode made some things easier, but many other things harder, so in the end it just wasn't worth it for most applications.
     
    (Reportedly, the programmers were able to influence the design of the "enhanced mid range" PIC16F devices, so THAT extended instruction set is much more compiler friendly. Plus it is completely backward compatible, so you don't have to switch modes.)
    post edited by ric - 2020/07/06 20:30:33

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    irun2
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    Re: which version of XC8 support PIC18 extended mode? 2020/07/06 20:28:45 (permalink)
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    1and0
    So why the extended instruction set still implemented in the latest PIC18 devices? I don't use it even when programming assembly. ;)
     
     




    I'm also wondering why....
    #11
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