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  3. February 2013

Re: QXXPTOD API from an ILE CL program

Trying to use floating point variables by value (passed or returned) in CL
is, as you have found, not going to work very well. There is another set of
math APIs though that you could use as they pass by reference. These APIs
can be found at
http://publib.boulder.ibm.com/infocenter/iseries/v5r4/topic/apis/ile5a5.htm#TBLMATHTAB.
This set of APIs doesn't include hypot -- your example function -- but you
could implement your own hypot function using these APIs (and appropriate
MI for data type conversion).

Bruce Vining

On Fri, Feb 15, 2013 at 6:29 AM, <paul.roy@xxxxxxx> wrote:

I tried using _LBCPYNV instead of QXXPTOD : the conversion works one way
but I got stuck one step further...
the data returned by the C function (as a return value) is not considered
as valid double when called from ILE CL... whilst the passed parameters
seems ok

_LBCPYNV... crashes with MCH1212

so the problem looks probably not in the conversion API but in the way
that returning double value is encapsulated ...
should I then admit (and regret) that any ILE procedure that returns a
double is not working from ILE CL ?

probably one of my next requirement to IBM: support of type "double/float"
in ILE CL... so that we can use all ILE features from CL.. and make CL
a full member of the ILE family...

hereunder is my code (NOT WORKING)

pgm
DCL VAR(&A) TYPE(*DEC) LEN(15 5) value(300)
DCL VAR(&B) TYPE(*DEC) LEN(15 5) VALUE(400)
DCL VAR(&C) TYPE(*DEC) LEN(15 5) value(0)
dcl &dblA *char 8
dcl &dblB *char 8
dcl &dblC *char 8

DCl &pckAttr *char 7
DCL VAR(&ITYPE) TYPE(*CHAR) STG(*DEFINED) LEN(1)
DEFVAR(&pckATTR)
DCL VAR(&ILEN) TYPE(*CHAR) STG(*DEFINED) LEN(2) DEFVAR
(&pckATTR 2)
DCL VAR(&IRSV) TYPE(*INT) STG(*DEFINED) LEN(4) DEFVAR(
&pckATTR 4)

dcl &dblAttr *char 7
DCL VAR(&OTYPE) TYPE(*CHAR) STG(*DEFINED) LEN(1)
DEFVAR(&dblATTR)
DCL VAR(&OLEN) TYPE(*CHAR) STG(*DEFINED) LEN(2) DEFVAR
(&dblATTR 2)
DCL VAR(&ORSV) TYPE(*INT) STG(*DEFINED) LEN(4) DEFVAR(
&dblATTR 4)

chgvar &itype x'03' /* PACKED*/
chgvar &ilen x'050F' /* 5 DEC 15 DIGITS */
chgvar &otype X'01' /*FLOAT */
chgvar &olen x'0008' /*len */

/* convert Packed decimal to Double */
CALLPRC ('_LBCPYNV') ( &dblA &dblAttr &A &pckAttr)
CALLPRC ('_LBCPYNV') ( &dblB &dblAttr &B &pckAttr)

/* call a C library Math function */
CALLPRC PRC('hypot') PARM((&DBLA *BYVAL) (&DBLB *BYVAL))
RTNVAL(&DBLC)

/*convert Double to Packed decimal */
CALLPRC ('_LBCPYNV') ( &C &pckAttr &dblC &dblAttr )
endpgm












From: Scott Klement <c400-l@xxxxxxxxxxxxxxxx>
To: "Bare Metal Programming IBM i (AS/400 and iSeries)"
<c400-l@xxxxxxxxxxxx>,
Date: 14/02/2013 22:31
Subject: Re: [C400-L] QXXPTOD API from an ILE CL program
Sent by: c400-l-bounces@xxxxxxxxxxxx



Do you have a good reason to use QXXPTOD instead of _LBCPYNV?
Personally, I prefer the latter.

Here's a program of mine that converts from double to packed -- I
imagine you can easily change it to convert the other way (but if you
can't figure it out, let me know)

PGM
DCL VAR(&LILIAN) TYPE(*CHAR) LEN(4)
DCL VAR(&FLOAT) TYPE(*CHAR) LEN(8)
DCL VAR(&GREGOR) TYPE(*CHAR) LEN(23)
DCL VAR(&SECONDS) TYPE(*DEC) LEN(15 0)
DCL VAR(&CHARSEC) TYPE(*CHAR) LEN(15)

DCL VAR(&IATTRIB) TYPE(*CHAR) LEN(7)
DCL VAR(&OATTRIB) TYPE(*CHAR) LEN(7)

/* Get Current Local Time */

CALLPRC PRC(CEELOCT) PARM(&LILIAN +
&FLOAT +
&GREGOR +
*OMIT )

/* To convert the floating point to packed, we need +
to tell the _LBCPYNV builtin what the formats of +
the input and output parameters are. This is +
done via an "attributes" data structure. There +
will be one for the input and one for the output.+
+
In consists of the following fields: +
+
Pos Len Description +
--- --- ------------------------------------ +
1 1 Data type (x'01'=float, x'03=packed) +
2 2 Field length (and decpos) +
for float, this must be 4 or 8 +
for packed, pos 2=decpos, +
pos 3=total digits +
4 4 Reserved (should be binary zeroes) +
*/

CHGVAR VAR(%SST(&IATTRIB 1 1)) VALUE(X'01')
CHGVAR VAR(%BIN(&IATTRIB 2 2)) VALUE(8)
CHGVAR VAR(%BIN(&IATTRIB 4 4)) VALUE(0)

CHGVAR VAR(%SST(&OATTRIB 1 1)) VALUE(X'03')
CHGVAR VAR(%SST(&OATTRIB 2 1)) VALUE(X'00')
CHGVAR VAR(%SST(&OATTRIB 3 1)) VALUE(X'0F')
CHGVAR VAR(%BIN(&OATTRIB 4 4)) VALUE(0)

/* Call the _LBCPYNV MI builtin to convert from float +
to packed. */

CALLPRC PRC('_LBCPYNV') PARM(&SECONDS +
&OATTRIB +
&FLOAT +
&IATTRIB )


/* Create a message that tells what the results were: */

CHGVAR VAR(&CHARSEC) VALUE(&SECONDS)

SNDUSRMSG MSG('The time' *BCAT &GREGOR *BCAT +
'is' *BCAT &CHARSEC *BCAT 'seconds +
from 14 Oct 1582.')
ENDPGM

More info about this MI builtin can be found in the IBM i Information
Center:
http://tinyurl.com/lbcpynv


On 2/14/2013 6:59 AM, paul.roy@xxxxxxx wrote:
Hello,

I would like to use C math functions in a CL program... but most of
those
functions use doubles.. which are not supported in ILE CL...
so my idea was to use QXXPTOD do convert to a internal value passed to
the
math function and then convert the result back to packed

this is just an example of what I would like to work in CL

pgm
DCL VAR(&A) TYPE(*DEC) LEN(15 5) value(300)
DCL VAR(&B) TYPE(*DEC) LEN(15 5) VALUE(400)
DCL VAR(&C) TYPE(*DEC) LEN(15 5) value(0)
dcl &dblA *char 8
dcl &dblB *char 8
dcl &dblC *char 8
DCL VAR(&DIG) TYPE(*INT) VALUE(15)
DCL VAR(&DEC) TYPE(*INT) VALUE(5)
/* convert Packed decimal to Double */
CALLPRC PRC(QXXPTOD) PARM((&A *BYREF) (&DIG *Byval) (
&DEC
*byval)) RTNVAL(&DBLA)
CALLPRC PRC(QXXPTOD) PARM((&B *BYREF) (&DIG *Byval) (
&DEC
*byval)) RTNVAL(&DBLB)
/* call a C library Math function */
CALLPRC PRC('hypot') PARM((&DBLA *BYVAL) (&DBLB
*BYVAL))
RTNVAL(&DBLC)
/*convert Double to Packed decimal */
CALLPRC PRC(QXXDTOP) PARM((&C *byref) (&DIG *Byval) (
&DEC
*byval) (&DBLC *byval))
endpgm

I know there are other ways and other languages but I am just trying to
understand why this is not working in ILE CL.


thanks

Paul


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