[Coco] Need some advice
Greg
glaw at live.com
Sun May 22 00:22:49 EDT 2016
If I was one of those persons on Delphi that said something like this,
maybe one day I'll get the taste of my foot out of my mouth. :-)
I'm not surprised in the least that hand-craft assembly can be
significantly faster than similar C code. The compiler makes it easier
to develop code, but the optimizations applied were very limited and
somewhat crude in the '80s. C compilers of the day commonly supported
embedded assembly code specifically so that portions of the code could
be optimized by a human. It should have been common knowledge by
everyone that the C compilers of the day would never match human
optimized assembly code.
I think the C/C++ compilers today have significantly better optimizers,
but I'm not quite willing to bet a nickle that machine-generated C code
can always match human-generated assembly. On the other hand, I'm not
quite so sure I could create assembly code on a modern processor any
more.
On 5/21/2016 11:10:12 PM, "Dave Philipsen" <dave at davebiz.com> wrote:
>When I wrote Supercomm over 25 years ago the primary impetus was to
>have an OS9 terminal program that could download via xmodem and ymodem
>significantly faster than a popular program that was then available
>which was written in C. Certain persons on Delphi and Compuserve
>chided me and said that a communications program written in C would be
>every bit as fast as one written in assembler. Back then time was
>money. Many BBSs were long distance calls and we paid by the minute.
>So, I did some tests. I wrote what eventually became Supercomm and
>compared it against the program which was written in C. At the time, I
>realized speed improvements somewhere in the neighborhood of 10%, as I
>recall, when downloading files from the same BBS with the same modem.
>I concluded that part of the reason was more optimized code from
>writing in assembler as well as calculating checksum on the fly instead
>at the end of each received block. With the advent of faster
>processors and better C compilers I'm sure that the gap between
>assemblers and C compilers has narrowed.
>
>Dave Philipsen
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