Specifications

Altera Corporation 8–73
October 2007 Nios II Processor Reference Handbook
mulxss
mulxss
multiply extended signed/signed
Operation:
rC
←
((signed) rA) × ((signed) rB))
63..32
Assembler Syntax:
mulxss rC, rA, rB
Example:
mulxss r6, r7, r8
Description:
Treating rA and rB as signed integers,
mulxss multiplies rA times rB, and stores the
32 high-order bits of the product to rC.
Nios II processors that do not implement the
mulxss instruction cause an
unimplemented-instruction exception.
Usage:
Use
mulxss and mul to compute the full 64-bit product of two 32-bit signed integers.
Furthermore,
mulxss can be used as part of the calculation of a 128-bit product of
two 64-bit signed integers. Given two 64-bit integers, each contained in a pair of 32-
bit registers, (S1 : U1) and (S2 : U2), their 128-bit product is (U1 × U2) + ((S1 × U2)
<< 32) + ((U1 × S2) << 32) + ((S1 × S2) << 64). The
mulxss and mul instructions
are used to calculate the 64-bit product S1 × S2.
Instruction Type: R
Instruction Fields: A = Register index of operand rA
B = Register index of operand rB
C = Register index of operand rC
313029282726252423222120191817161514131211109876543210
ABC0x1f 00x3a