| 主权项 |
1. A method for determining whether a decimal floating point number is safe or unsafe, said method comprising:
obtaining a machine instruction for execution, the machine instruction comprising an opcode, a register field, an index field, a base field and a displacement value; and obtaining, by a processor of a processing environment, a first operand in a decimal floating point format, the first operand included in a register specified by the register field;
performing a function defined by the opcode of the machine instruction of determining whether the first operand is a safe decimal floating point number or is a potentially unsafe decimal floating point number, said function comprising:determining a data group and a sign for the first operand;determining a plurality of second operand bits using the index field, base field and displacement value of the machine instruction, each bit of the plurality of second operand bits corresponding to a data group and sign combination;selecting a bit of the plurality of second operand bits based on the data group and sign determined for the first operand;determining a value of the selected bit; andsetting a condition code based on the value of the selected bit, the condition code indicating whether a result of a floating point operation is safe or potentially unsafe wherein unsafe indicates that use of a larger data format would produce a different value or quantum. |
