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IDT MIPS32 4Kc Processor Core
Processor Core Instructions
79RC32438 User Reference Manual
2 - 87
November 4, 2002
Notes
MADD - Multiply and Add Word
The MADD instruction multiplies two words and adds the result to the HI/LO register pair. The 32-bit
word value in the GPR rs is multiplied by the 32-bit value in the GPR rt, treating both operands as signed
values, to produce a 64-bit result. The product is added to the 64-bit concatenated values in the HI and LO
register pair. The resulting value is then written back to the HI and LO registers. No arithmetic exception
occurs under any circumstances.
MADDU - Multiply and Add Unsigned Word
The MADDU instruction multiplies two unsigned words and adds the result to the HI/LO register pair.
The 32-bit word value in the GPR rs is multiplied by the 32-bit value in the GPR rt, treating both operands
as unsigned values, to produce a 64-bit result. The product is added to the 64-bit concatenated values in
the HI and LO register pair. The resulting value is then written back to the HI and LO registers. No arithmetic
exception occurs under any conditions.
MSUB - Multiply and Subtract Word
The MSUB instruction multiplies two words and subtracts the result from the HI/LO register pair. The 32-
bit word value in the GPR rs is multiplied by the 32-bit value in the GPR rt, treating both operands as signed
values, to produce a 64-bit result. The product is subtracted from the 64-bit concatenated values in the HI
and LO register pair. The resulting value is then written back to the HI and LO registers. No arithmetic
exception occurs under any circumstances.
MSUBU - Multiply and Subtract Unsigned Word
The MSUBU instruction multiplies two unsigned words and subtracts the result from the HI/LO register
pair. The 32-bit word value in the GPR rs is multiplied by the 32-bit value in the GPR rt, treating both oper-
ands as unsigned values, to produce a 64-bit result. The product is subtracted from the 64-bit concatenated
values in the HI and LO register pair. The resulting value is then written back to the HI and LO registers. No
arithmetic exception occurs under any circumstances.
MUL - Multiply Word
The MUL instruction multiplies two words and writes the result to a GPR. The 32-bit word value in the
GPR rs is multiplied by the 32-bit value in the GPR rt, treating both operands as signed values, to produce
a 64-bit result. The least-significant 32 bits of the product are written to the GPR rd. The contents of the HI
and LO register pair are not defined after the operation. No arithmetic exception occurs under any circum-
stances.
SSNOP- Superscalar Inhibit NOP
The 4Kc processor core treats this instruction as a regular NOP.
Processor Core Instructions
The 4Kc Processor Core Instructions are discussed in Appendix A of this user manual.