Specifications

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 instruc‐
tion 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 x U2) + ((S1 x U2) << 32) + ((U1 x S2) << 32) + ((S1 x S2)
<< 64). The mulxss and mul instructions are used to calculate
the 64-bit product S1 x S2.
Exceptions
Unimplemented instruction
Instruction Type
R
Instruction Fields
A = Register index of operand rA
B = Register index of operand rB
C = Register index of operand rC
Bit Fields
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
A B C 0x1f
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
0x1f 0 0x3a
mulxsu
Instruction
multiply extended signed/unsigned
Operation
rC ← ((signed) rA) x ((unsigned) rB))
63..32
Assembler Syntax
mulxsu rC, rA, rB
Example
mulxsu r6, r7, r8
8-60
mulxsu
NII51017
2015.04.02
Altera Corporation
Instruction Set Reference
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