Writing $Functions with Your Own Error Messages - Rocket Software

Writing $Functions with Your Own Error Messages
In the $INSCHAR source listing, I have added code to test the string argument to
enforce those two rules:
1) The argument must be exactly 10 bytes
2) The argument must be numeric: digits 0-9
The Modified $INSCHAR Code
The blue lines of code below were added to implement error checking.
**$INSCHAR Receives a numeric character string (ARG1) of length 10
* and returns that character string with the single
* character (ARG2) inserted in col 4 and col 7 of ARG1.
* Col: 4 7
* | |
* v v
* ARG1: 1234567890
* ARG2: _ (DEFAULT)
*
* RETURN: 123_456_7890
$INSCHAR ENTER
MVC BUF2(1),INSDEFC Get default character for insert
ARG 2,NOARG=INSDEF If ARG2 not provided, use default
L R2,4(X1) Type of ARG - required for RTSTRL
CCALL RTSTRL Call ReTurn STRing with Length
* Returns A(ARG2)-1 in R1 and len in R2
MVC BUF2(1),1(R1) Move ARG2 (char for insert) to BUF2
INSDEF ARG 1,NOARG=INSDONE If ARG1 not provided, return null
L R2,4(X1) Type of ARG - required for RTSTRL
CCALL RTSTRL Returns A(ARG1)-1 in R1 and len in R2
C R2,=F'10' Is length of ARG1 exactly 10 bytes?
BNE INSERR1 No, issue error
* Ensure ARG1 is numeric only
MVC BUF1(10),1(R1) Move ARG1 to BUF1
L X1,KAPFF A(KZFF) = 256 foxes
MVC KAJUNK(256),0(X1) Setup table for Translate and Test
MVC KAJUNK+C'0'(C'9'-C'0'+1),KA00 Get zeroes for numbers
BCTR R2,0 Subtract one from length
EX R2,$INSNUM TRT BUF1(0),KAJUNK
IF BNZ If non-numeric character found
ERROR 2,OPT=USER String must be numeric 0-9
B INSDONE Set len of ret string to 0 and return
IFEND
LA R2,10 Get len back in R2
MVC BUF1(20),KA00 Clear BUF1
MVC BUF1(3),1(R1) Move 1st 3 chars of ARG1 to BUF1
MVC BUF1+3(1),BUF2 Insert ARG2
MVC BUF1+4(3),4(R1) Move next 3 chars of ARG1 to BUF1
MVC BUF1+7(1),BUF2 Insert ARG2
S R2,=F'6' Subtract (3+3) bytes from ARG1 length
EX R2,$INSMVC Move rest of ARG1 to BUF1
A R2,=F'8' Get new len of ARG1(6+2+rest of ARG1)
LA R1,BUF1-1 Get A(BUF1) minus 1
B INSRET
INSERR1 ERROR 1,OPT=USER String length must be 10 bytes
INSDONE SR R2,R2 No ARG1, set return string len to 0
Rocket M204 April 2009
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