HLASM Language Reference

DC Instruction—Decimal Constants
| Remember that commas separate operands. For readability, use spaces instead,
| as shown in this example:
| TWOCONS DC F'123,445' Two constants
| ONECON DC F'123 456' One constant
Decimal Constants—P and Z
The decimal constants let you introduce data in a form suitable for operations on
decimal data. The packed decimal constants (P-type) are used for processing by
the decimal instructions. The zoned decimal constants (Z-type) are in the form
(EBCDIC representation) you can use as a print image, except for the digit in the
rightmost byte.
The nominal value can be a signed (plus is assumed if the number is unsigned)
decimal number. A decimal point may be written anywhere in the number, or it
may be omitted. The placement of a decimal point in the definition does not affect
the assembly of the constant in any way, because the decimal point is not
assembled into the constant; it only affects the integer and scaling attributes of the
symbol that names the constant.
The specified digits are assumed to constitute an integer (see ▌1▐ in Figure 43).
You may determine correct decimal point alignment either by defining data so that
the point is aligned or by selecting machine instructions that operate on the data
correctly (that is, shift it for purposes of decimal point alignment).
Decimal constants are assembled as follows:
Packed Decimal Constants: Each digit is converted into its 4-bit binary coded
decimal equivalent (see ▌2▐ in Figure 43). The sign indicator (see ▌3▐ in
Figure 43) is assembled into the rightmost four bits of the constant.
Zoned Decimal Constants: Each digit is converted into its 8-bit EBCDIC
representation (see ▌4▐ in Figure 43). The sign indicator (see ▌5▐ in Figure 43)
replaces the first four bits of the low-order byte of the constant.
The range of values that can be assembled into a decimal constant is shown
below:
Type of
decimal
constant
Packed
Zoned
Range of values that
can be specified
1031−1 to −1031
1016−1 to −1016
For both packed and zoned decimals, a plus sign is translated into the hexadecimal
digit C, a minus sign into the digit D. The packed decimal constants (P-type) are
used for processing by the decimal instructions.
If, in a constant with an implicit length, an even number of packed decimal digits is
specified, one digit is left unpaired because the rightmost digit is paired with the
sign. Therefore, in the leftmost byte, the leftmost four bits are set to zeros and the
rightmost four bits contain the unpaired (first) digit.
Chapter 5. Assembler Instruction Statements 151