Exact control bits vary by implementation. DCRs DCRs are similar to SPRs in that they give status and control information, but DCRs are for resources outside the processor core. They also provide access to SPRs and DCRs. Instructions Table 2 lists different instruction categories, and the types of instructions that exist in that category. Instructions are first decoded by the upper 6 bits, in a field called the primary opcode.
Operands can be registers or immediate values.
Many instructions exist for performing arithmetic operations, including add, subtract, negation, compare, multiply and divide. Many forms exist for immediate values, overflow detection, and carry in and out. Multiply and divide instruction performance varies among implementations, as these are typically multi-cycle instructions. Logical Instructions Table 3. PowerPC Logical Instructions AND OR Exclusive OR Rotate and Mask Shift Misc.