Max
Nice work. Yes. indeed. all cases of float literals should have f
after them ....
I used to just force doubles to floats but I realised that was
lazy programming so I think specific float f literal is important.
In contrast to Bruce, I WOULD change the main source to float
literals, UNLESS they MUST be doubles.
Running on the PC hides alot of evils (or another way to look at
it - buys you alot of flexibility) .
Good on the divides, also, Divides suck. I've never looked at the
code in detail. I'll get it up on the M7 soon.
I think the code needs a hose through it to fix alot of this stuff
that is not suited to microcontroller platforms. Yes yes I know
David likes it truly X platform but IMO one should write with
regard for smaller platforms if they are at all expected to be
targets.. I guess that comes from me having a background of
always being hard up for processor cycles... When I write code,
aware that divides are hard , I always change them to multiplies
if I possibly can and only do divides if I cannot possibly avoid
it
good work again!
cheers
On 20/06/2016 7:18 PM, Bruce Perens
wrote:
Many, perhaps most, CPUs have a float type that is
slower than double, because their internal hardware is
double-only and they convert float to double and back to float
on every operation. Don't change the main source to float types.
Use macros, typedefs, or compiler switches. Also, David will
probably not be happy of the code is made less readable.
Hello,
Good news, after some work it seem I've got a working
solution.
@Steve, note that the CMSIS do not provide function
for atan2() and floor()...
First I've tested to do only single precision operation
(do not allow double operation because M4 cannot handle
double precision operation on the hardware FPU).
In Codec2 it seem that a lot of operation involve
double which seem not always necessary, for example all
the define M_PI and other value which are not defined
whith the suffix 'f' are considered by C ANSI code to be
double.
So operation with those define are double operation not
optimized.
The same occur each time you do an operation with a
litteral without the 'f' suffix. For example (0.5*x or
0.5+x is a double operation which I change to "0.5f*x" and
"0.5f+x").
After fixing this in the Codec, I came to a speedup of
at least 10% for the decoding!!
I cannot say if this is a good hint for speed up and if
you can live with the loss of precision but if yes, maybe
this fix can be done in your main repository
After that I tested some other compile option and
optimization (O2 and some other inlining) without success.
Finally I tested to pass the floating point mode of the
target from "strict" to "relaxed".
See the definition in wiki:
Relaxed
mode prioritizes speed over strict correctness. In
relaxed mode, the compiler may perform speed
optimizations at the expense of reducing the precision
of some calculations, typically a tiny amount. For
instance, (X/3) is not precisely equivalent to
(X*(1.0/3)), but in relaxed mode, the compiler is
allowed to make this transformation anyway, as
multiplication is much faster than division.
Changing that provide me a speed up of about 45%!!!!
Here are the encoding time after all fix:
-Encoding time without
modification was between 25ms and 42ms / After modification it is
between : 18ms and 19ms so a speed up of about 55%.
My processor will be loaded at 48% for
encoding sound at 8000Khz.
-Decoding time without
modification was between 39ms and 56ms / After modification it is
between : 23ms and 27ms so a speed up of about 52%. My processor will be loaded
at 68% for decoding sound at 8000Khz.
I've played back the encoded stream at 1200bps and
1300bps and everything seem okay: I cannot hear any
strong difference between the encoded version with
modification and without my modification.
Hope that this will help some other people to get it
working on their target.
Regards,
Max
What NetFlow Analyzer can do for you? Monitors network
bandwidth and traffic
patterns at an interface-level. Reveals which users, apps, and
protocols are
consuming the most bandwidth. Provides multi-vendor support
for NetFlow,
J-Flow, sFlow and other flows. Make informed decisions using
capacity planning
reports. http://sdm.link/zohomanageengine_______________________________________________
Freetel-codec2 mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/freetel-codec2
------------------------------------------------------------------------------
What NetFlow Analyzer can do for you? Monitors network bandwidth and traffic
patterns at an interface-level. Reveals which users, apps, and protocols are
consuming the most bandwidth. Provides multi-vendor support for NetFlow,
J-Flow, sFlow and other flows. Make informed decisions using capacity planning
reports. http://sdm.link/zohomanageengine
_______________________________________________
Freetel-codec2 mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/freetel-codec2
|
