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EIP-7939 Count leading zeros (CLZ) opcode

FinalCorecreated 2025-04-281 later proposal build on it

Opcode to count the number of leading zero bits in a 256-bit word

Authors: Vectorized (@Vectorized), Georgios Konstantopoulos (@gakonst), Jochem Brouwer (@jochem-brouwer), Ben Adams (@benaadams), Giulio Rebuffo (@Giulio2002)

Functions this standard introduces (1)

0x30244f7aclz(uint256)pure

Built on by (1)

Later proposals that name this one in their requires field.

EIP-7607Hardfork Meta - Fusaka

What the specification covers

AbstractMotivationSpecificationRationaleThe special 0 casePreference over CTZ (count trailing zeros)Gas costBackwards CompatibilityTest CasesSecurity ConsiderationsCopyright

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