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 Posted: Feb 09, 2010 - 05:16 AM |
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Joined: Dec 30, 2004
Posts: 4295
Location: Melbourne,Australia
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| It used to be fun but tedious to reduce state tables to the required logic, but now we have logic compilers that allow us to use a high level description and produce output in next to zero time. Much the same thing as C vs Asm. You won't see much asm in my recently written stuff..... |
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Posted: Feb 09, 2010 - 05:44 AM |
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Joined: Mar 28, 2001
Posts: 12827
Location: Sydney, Australia (Gum trees, Koalas and Kangaroos, No Edelweiss)
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Quote:
We couldn't beat the compiler's code
You mean the compiler's code writer..he/she/them was/were much more experienced in asm coding than the "very experienced developers".....  |
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John Samperi
Ampertronics Pty. Ltd.
www.ampertronics.com.au
* Electronic Design * Custom Products * Contract Assembly
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Posted: Feb 09, 2010 - 06:48 AM |
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Joined: Dec 06, 2008
Posts: 53
Location: india
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what i meant easy was that i had done assembly programming course in college and it was quite the same as 6502 except the sizes,memory,speed,registers,etc. so i easily adapted the assembly language of 6502.
But i feel C is good than asm as abstraction level is more. i.e. to write loop in C is 1 line code whereas in asm we have to write 5-6 lines...
So i prefer C but have no objection for using assembly. |
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regards
www.darshshah.blogspot.com
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Posted: Feb 09, 2010 - 06:49 AM |
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Joined: Dec 30, 2004
Posts: 4295
Location: Melbourne,Australia
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| The compiler writers write rules that for a human to implement would take an inordinate amount of time to implement each time a small change was done - register allocation for example. A human tends to write more 'regular' code, for example with an AVR we might use R16 as a temp register whereas the compiler will use what it wants given the circumstances at that point in the code. If we wrote code that way it would be a pig to maintain. |
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Posted: Feb 09, 2010 - 07:28 AM |
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Joined: Dec 16, 2005
Posts: 1390
Location: Bratislava, Slovakia
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stevech wrote:
(a MIPS).
MIPS is one of the least human RISCs. And RISCs are deliberately built to be used with a compiler.
But you all miss the point. The point is not that A or B is better or worse; but that A or B is fit for a purpose.
JW |
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Posted: Feb 09, 2010 - 08:46 AM |
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Joined: Oct 07, 2002
Posts: 395
Location: Germany
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wek wrote:
But you all miss the point. The point is not that A or B is better or worse; but that A or B is fit for a purpose.
And to answer that you need to know the costs and benefits of each approach. I and probably others have been ignoring the suitability of A or B because we don't know the OP's purpose. |
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Posted: Feb 09, 2010 - 11:15 AM |
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Joined: Jul 18, 2005
Posts: 33138
Location: (using avr-gcc in) Finchingfield, Essex, England
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Quote:
Most C afficionados sincerely do believe that asm is hard and C is easy
For me it's not a question of "hard" vs "easy" but more vs less typing. You can achieve in one line of C what you'd need to type 10 lines of Asm to do (the output of the C compiler will show this regularly). THAT is why I switched to using C in about 1995 after having done Asm (mainly Z80) for 15 years. In my time I've written a WYSIWYG word processor/spreadsheet in Z80 Asm: http://web.ukonline.co.uk/cliff.lawson/anne.htm and http://toastytech.com/guis/pcw.html as well as some of the Sinclair Spectrum operating system so I've done more than my share of Asm but if I had the time again and the tools had been available at the time I'd have done the word pro in C (maybe not the Spectrum - that did need hand optimised Asm) |
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Posted: Feb 09, 2010 - 05:11 PM |
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Joined: Dec 18, 2001
Posts: 2939
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js wrote:
Quote:
We couldn't beat the compiler's code
You mean the compiler's code writer..he/she/them was/were much more experienced in asm coding than the "very experienced developers".....
I disagree. The algorithms used for register/RAM allocation in non-trivial nested loops and function calls, I contend, are impractical for a person to do.
I am not a dope! |
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Posted: Feb 09, 2010 - 11:14 PM |
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Joined: Dec 15, 2008
Posts: 587
Location: Brisbane, Australia
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stevech wrote:
We could beat the compiler for smaller functions. And we probably could for a computer with fewer registers than the one we were using (a MIPS).
I can't remember who to attribute the quote to, but someone once said:
"Beginners should not optimise code. Experts should not optimise code... yet"
The quote was about profiling code before introducing "efficiency" hacks. IMO, writing in assembler is one of those.
-- Damien |
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Posted: Feb 10, 2010 - 12:02 AM |
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Joined: Oct 07, 2002
Posts: 978
Location: Skørping Denmark
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Kartman:
Quote:
A human tends to write more 'regular' code, for example with an AVR we might use R16 as a temp register whereas the compiler will use what it wants given the circumstances at that point in the code.
For me it's the other way round, the C compiler allways want to use the samme registers over and over again that give a lot of useless mov's that you can avoid. (And yes I do know that the compiler do it that way because the lib's are written to a special register use). |
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