MicroBlaze Processor Reference Guide 261
UG984 (v2018.2) June 21, 2018 www.xilinx.com
Chapter 5: MicroBlaze Instruction Set Architecture
mulh
Multiply High
mulh
rD, rA, rB
0 1 0 0 0 0 rD rA rB 0 0 0 0 0 0 0 0 0 0 1
0 6 11 16 21
31
Description
Multiplies the contents of registers rA and rB and puts the result in register rD. This is a 32-bit by 32-
bit signed multiplication that will produce a 64-bit result. The most significant word of this value is
placed in rD. The least significant word is discarded.
Pseudocode
(rD) ← MSW( (rA) × (rB) ), signed
Registers Altered
•rD
Latency
• 1 cycle with C_AREA_OPTIMIZED=0 or 2
• 3 cycles with
C_AREA_OPTIMIZED=1
Notes
This instruction is only valid if the target architecture has multiplier primitives, and if present, the
MicroBlaze parameter C_USE_HW_MUL is set to 2 (Mul64).
When MULH is used, bit 30 and 31 in the MUL instruction must be zero to distinguish between the two
instructions. In previous versions of MicroBlaze, these bits were defined as zero, but the actual values
were not relevant.
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