Count Instruction Extension

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Initially implemented in the EV67 processor, the Count Instruction Extension adds three instructions to count bits.

Added Instructions

Mnemonic Description
ctlz Count Leading Zeros
ctpop Count Population (Count number of 1's)
cttz Count Trailing Zeros

Determining Presence

To determine the presence of CIX, use the amask instruction.

Latency and Slotting

The CIX instructions are slotted U0 and have a latency of 3 cycles. [1].