Re: how to create unsigned hexadecimal initial value

I think even the more recent examples are easy to explain in terms of the
definition I gave for H literals.

Example 1:

DCL DD NN BIN(2) INIT(H'8000');
Diagnostics
Initial value for data object too large.

The above is equivalent to initializing NN with 32768, which is greater
than the largest positive number that can be represented by BIN(2).  So,
the error message is correct.  If the intent is to initialize NN with
-32768, then use one of the following forms:
DCL DD NN BIN(2) INIT(H'FFFF8000');
DCL DD NN BIN(2) INIT(-32768);

Example 2:

DCL DD NN BIN(2) INIT(H'FFFF')
Diagnostics
Initial value for data object too large.

Same problem here.  65535 (H'FFFF') is too large to be represented by a
BIN(2) data object.  Use the following forms to initialize NN to -1:
DCL DD NN BIN(2) INIT(H'FFFFFFFF');
DCL DD NN BIN(2) INIT(-1);

Example 3:

DCL DD NN BIN(2);
DCL DD XX CHAR(2) DEF(NN);

CPYNV  NN, -1;
AND(S) NN,H'0003'; /* Equivalent to AND(S) NN, 3; */
CVTHC MSG-TEXT(1:4), XX;
CALLI SHOW-MESSAGE, *, .SHOW-MESSAGE;    <==== shows  0300    wrong

H'00003' represents the value 3 and has length 1 (unlike character
constants, the leading zeros are not significant).  Based on the
specification for AND(S), the shorter operand is padded on the right with
zeros.  So, the expected result of ANDing op1=x'FFFF' with op2=x'03' is
x'0300'.

A fourth example was given, but I think it has to do with strange behavior
from CPYBLA rather than anything to do with H literals.   The example was
this:

DCL DD XX CHAR(2)
CPYBLA XX,H'1234';  /* WRONG --> yields  result   3400. */

The same result is produced if the H literal is replaced with its decimal
equivalent, 4660.  For some reason, operand 2 is treated as a one byte
value (just the low order byte).  I'll investigate this further.

Bob Donovan


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