HLASM Language Reference

DC Instruction
Floating-point constant E, EH 0 to 14
Floating-point constant D, DH 0 to 14
Floating-point constant L, LH 0 to 28
The scale modifier is written as Sn, where n is either a decimal self-defining term,
or an absolute expression enclosed in parentheses. Both forms of the modifier's
value n can be preceded by a sign; if no sign is present, a plus sign is assumed.
Scale Modifier for Fixed-Point Constants: The scale modifier for fixed-point
constants specifies the power of two by which the fixed-point constant must be
multiplied after its nominal value has been converted to its binary representation,
but before it is assembled in its final scaled form. Scaling causes the binary point
to move from its assumed fixed position at the right of the rightmost bit position.
Notes:
1. When the scale modifier has a positive value, it indicates the number of binary
positions occupied by the fractional portion of the binary number.
2. When the scale modifier has a negative value, it indicates the number of binary
positions deleted from the integer portion of the binary number.
3. When low-order positions are lost because of scaling (or lack of scaling),
rounding occurs in the leftmost bit of the lost portion. The rounding is reflected
in the rightmost position saved.
Scale Modifier for Hexadecimal Floating-Point Constants: The scale modifier
for hexadecimal floating-point constants must have a positive value. It specifies the
number of hexadecimal positions that the fractional portion of the binary
representation of a floating-point constant is shifted to the right. The hexadecimal
point is assumed to be fixed at the left of the leftmost position in the fractional field.
When scaling is specified, it causes an unnormalized hexadecimal fraction to be
assembled (unnormalized means the leftmost positions of the fraction contain
hexadecimal zeros). The magnitude of the constant is retained, because the
exponent in the characteristic portion of the constant is adjusted upward
accordingly. When non-zero hexadecimal positions are lost, rounding occurs in the
leftmost hexadecimal position of the lost portion. The rounding is reflected in the
rightmost position saved.
Exponent Modifier
The exponent modifier specifies the power of 10 by which the nominal value of a
constant is to be multiplied before it is converted to its internal binary
representation. It can only be used with the fixed-point (H and F) and floating-point
(E, D, and L) constants. The exponent modifier is written as En, where n can be
either a decimal self-defining term, or an absolute expression enclosed in
parentheses.
The decimal self-defining term or the expression can be preceded by a sign. If no
sign is present, a plus sign is assumed. The range for the exponent modifier is −85
to +75. If a type extension is used to define a floating-point constant, the exponent
modifier can be in the range −2 31 to 2 31 −1. If the nominal value cannot be
represented exactly, a warning message is issued.
Chapter 5. Assembler Instruction Statements 139