HLASM Language Reference

SETA Instruction
5. An arithmetic-valued function is a term.
6. An arithmetic expression must not contain two terms in succession.
7. An arithmetic expression must not contain a decimal point. For example,
123.456 is not a valid arithmetic term, but 123 is.
8. An arithmetic expression must not contain spaces between an operator and a
term, nor between two successive operators except for built-in functions using
the “logical-expression format” described at “Logical (SETB) Expressions” on
page 365.
9. Ordinary symbols specified in arithmetic expressions must be defined before
the arithmetic expression is encountered, and must have an absolute value.
10. An arithmetic expression can contain up to 24 unary and binary operators, and
is limited to 255 levels of parentheses. The parentheses required for sublist
notation, substring notation, and subscript notation count toward this limit.
An arithmetic expression must not contain two terms in succession; however,
any term may be preceded by up to 24 unary operators. +&A−&B is a valid
operand for a SETA instruction. The expression &FIELD+− is invalid because it
has no final term.
Evaluation of Arithmetic Expressions: The assembler evaluates arithmetic
expressions during conditional assembly processing as follows:
1. It evaluates each arithmetic term.
2. It carries out arithmetic operations from left to right. However,
a. It carries out unary operations before binary operations, and
b. It carries out the binary operations of multiplication and division before the
binary operations of addition and subtraction.
3. In division, it gives an integer result; any fractional portion is dropped. Division
by zero gives a 0 result.
4. In parenthesized arithmetic expressions, the assembler evaluates the innermost
expressions first, and then considers them as arithmetic terms in the next outer
level of expressions. It continues this process until the outermost expression is
evaluated.
5. The computed result, including intermediate values, must lie in the range −2 31
| through +2 31 −1. (Note that if the value −2 31 is substituted in a SETC
| expression, its magnitude, 2147483648, is invalid if subsequently substituted in
| a SETA expression.)
SETC Variables in Arithmetic Expressions: The assembler permits a SETC
variable to be used as a term in an arithmetic expression if the character string
value of the variable is a self-defining term. The value represented by the string is
assigned to the arithmetic term. A null string is treated as zero.
Examples:
LCLC
&C(5)
&C(1) SETC 'B''11'''
&C(2) SETC 'C''A'''
&C(3) SETC '23'
&A SETA &C(1)+&C(2)–&C(3)
Chapter 9. How to Write Conditional Assembly Instructions 359