HLASM: V1R6 Language Ref

DC instructionpoint is assumed to be fixed at the left of the leftmost position in the fractionalfield. When scaling is specified, it causes an unnormalized hexadecimal fraction tobe assembled (unnormalized means the leftmost positions of the fraction containhexadecimal zeros). The magnitude of the constant is retained, because theexponent in the characteristic portion of the constant is adjusted upwardaccordingly. When non-zero hexadecimal positions are lost, rounding occurs in theleftmost hexadecimal position of the lost portion. The rounding is reflected in therightmost position saved.Exponent modifierThe exponent modifier specifies the power of 10 by which the nominal value of aconstant is to be multiplied before it is converted to its internal binaryrepresentation. It can only be used with the fixed-point (H and F) andfloating-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 expressionenclosed in parentheses.The decimal self-defining term or the expression can be preceded by a sign. If nosign is present, a plus sign is assumed. The range for the exponent modifier is −85to +75. If a type extension is used to define a floating-point constant, the exponentmodifier can be in the range −2 31 to 2 31 −1. If the nominal value cannot berepresented exactly, a warning message is issued.Notes:1. Don’t confuse the exponent modifier with the exponent that can be specified inthe nominal value subfield of fixed-point and floating-point constants.The exponent modifier affects each nominal value specified in the operand,whereas the exponent written as part of the nominal value subfield only affectsthe nominal value it follows. If both types of exponent are specified in a DCoperand, their values are added together before the nominal value is convertedto binary form. However, this sum must lie within the permissible range of −85to +75, unless a type extension is specified.2. The value of the constant, after any exponents have been applied, must becontained in the implicitly or explicitly specified length of the constant to beassembled.Subfield 6: Nominal ValueThe syntax for coding the nominal value is shown in the subfield format on page126.You must specify the nominal value subfield unless a duplication value of zero isspecified. It defines the value of the constant (or constants) described and affectedby the subfields that precede it. It is this value that is assembled into the internalbinary representation of the constant. Table 21 shows the formats for specifyingconstants.Table 21. Specifying constant valuesConstantTypeSingleNominal ValueMultipleNominal Value Page No.C 'value' not allowed 140G '' not allowed 144138 HLASM: V1R6 Language Ref