Decimal floating-point support on the IBM System z10 processor

The latest IBM zSeriest processor, the IBM System z10e processor, provides hardware support for the decimal floating-point (DFP) facility that was introduced on the IBM System z9t processor. The z9t processor implements the facility with a mixture of low-level software and hardware assists. Recently, the IBM POWER6e processor-based System pe 570 server introduced a hardware implementation of the DFP facility. The latest zSeries processor includes a decimal floating-point unit based on the POWER6 processor DFP unit that has been enhanced to also support the traditional zSeries decimal fixed-point instruction set. This paper explains the hardware implementation to support both decimal fixed point and DFP and the new software support for the DFP facility, including IBM z/OSt, Javae JIT, and C/Cþþ compilers, as well as support in IBM DB2t and middleware.