Just do some math

`1000 + 15 & -16`

Find out whether two expressions are equivalent

`let x = a + b in (x < a) == (x < max(a, b))`

*Prove* that two expressions are equivalent

`a ^ ((a ^ b) & mask) == (a & ~mask) | (b & mask)`

Find when two expressions are equal and when they are not

`x == -x`

Quantify some variables away to find values that always work

`forall x: -x == (x ^ m) - m`

Tip: a saved copy of this page works offline.

== binds less strongly than bitwise operators.

Finding proofs can be slow and often nothing is found at all.

The BDD structural matcher has not been fully ported yet.

SAT fallback now exists, using MiniSat compiled with Emscripten. This is brand new so expect bugs (not due to MiniSat, but for example I don't entirely trust my circuit builder and circuit-to-SAT converter). haroldbot should now give up early on (some) multiplications that would create a gigantic BDD.

In general, there *are* many bugs.

Since everything happens client-side, I don't get automatic bug reports. Please open an issue or contact me (eg via email or twitter @HaroldAptroot).

Overview of how haroldbot works.

`min = min_u, min_s``max = max_u, max_s``popcnt``nlz`number of leading zeroes`ntz`number of trailing zeroes`reverse`bit-reversal`hmul = hmul_u, hmul_s`high half of product`blsi, blsr, blsmsk, tzmsk`BMI operations`bzhi, pdep, pext`BMI2 operations`subus`subtraction with unsigned saturation (aka`dozu`)