Re: [EXTERNAL] Remove unprintable chars

You are correct - surprised nobody spotted that earlier and (much to my surprise) it does significantly change the results with Xlate coming out 5x faster.

So there must be an underlying machine function that Xlate maps to that allows the whole process to run down in microcode.

Interesting - thanks for pointing that out.


Jon Paris

On Nov 22, 2021, at 8:06 AM, Francois Lavoie <Francois.Lavoie@xxxxxxxxxxxxxxxxxxxx> wrote:

Why did u put the Xlate inside a for loop??
The Xlate *will* loop every char in the str parm
Remove the For/EndFor and time test it again


-----Original Message-----
From: RPG400-L <rpg400-l-bounces@xxxxxxxxxxxxxxxxxx> On Behalf Of Jon Paris
Sent: Friday, November 19, 2021 11:18
To: RPG programming on IBM i <rpg400-l@xxxxxxxxxxxxxxxxxx>
Subject: Re: [EXTERNAL] Remove unprintable chars

My first thought was the same as Bruce's - that an individual character loop would be by far the fastest approach.

You always have to remember that no magic is involved and that in order to implement %Xlate or %ScanRpl RPG still has to implement a character at a time loop unless there is can underlying system function that can perform the task - and even then that just moves that loop down closer to the hardware.

But so many in this thread seemed convinced that the BIF approach would be faster I decided to test and compare Francois' code with a simple loop.

The time difference is dramatic. The single char loop is orders of magnitude faster.

Run the following and see for yourself. On my system I get the following:

DSPLY Xlate took: 1094
DSPLY Loop took: 59

And those results are consistent.

Here's the code I used - if you spot a bug let me know.

**free

dcl-ds str;
strChar char(1) Dim(1000);
end-ds;

dcl-s blank64 char(64) inz;
dcl-s i int(5);
dcl-s startTime timestamp;
dcl-s endTime timestamp;

startTime = %timestamp();

for i = 1 to %elem(strChar);

str = X'12' + 'some string' +X'350A13';
str = %Xlate(X'000102030405060708090A0B0C0D0E0F+
101112131415161718191A1B1C1D1E1F+
202122232425262728292A2B2C2D2E2F+
303132333435363738393A3B3C3D3E3F'
: blank64
:str);
endfor;

endTime = %timestamp();

Dsply ( 'Xlate took: ' + %char(%diff( endTime : startTime : *MS )));


startTime = %timestamp();

for i = 1 to %elem(strChar);

if strChar(i) < X'40';
strChar(i) = *Blank;
endif;

endfor;

endTime = %timestamp();

Dsply ( 'Loop took: ' + %char(%diff( endTime : startTime : *MS )));


*InLr = *On;

On Nov 18, 2021, at 6:45 PM, Francois Lavoie <Francois.Lavoie@xxxxxxxxxxxxxxxxxxxx> wrote:

Here's the code I tested: ultra fast and ultra compact. A 1-liner
beats any slow do 1-char at a time multi-line of code loop dcl-s str
char(1000);

str=X'12'+'some string'+X'350A13';
str=%Xlate(X'000102030405060708090A0B0C0D0E0F+
101112131415161718191A1B1C1D1E1F+
202122232425262728292A2B2C2D2E2F+
303132333435363738393A3B3C3D3E3F'
:' '+
' '
:str);


make sure the 2nd parm of the Xlate bif has exactly 64 blanks

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