pressure is a congestion multiplier kept in the contract as a fixed point number with eighteen decimals. it changes once per block and only in response to how many tokens that block issued.
headroom = K − totalSupply budget = headroom >> 7 target = budget >> 1
the budget is the most a block may issue. it is one part in 128 of the headroom, so the opening block may issue 262 144 tokens, which is almost exactly what a full two eth pat issues at position zero, and the budget shrinks as the curve fills. target is half the budget, and one eth at the opening issues just under target.
at the start of every mint the contract settles pressure up to the current block. the block that last saw a mint applies its own multiplier: one plus the excess of its issuance over target, divided by eight targets. if that block had issued under target the multiplier is below one, and the result is floored at zero. if pressure was zero and the block crossed target, pressure is seeded at one sixty fourth first. every block since then was idle and multiplies pressure by seven eighths, computed as a power in fixed point with rounding down at each squaring. after five hundred and twelve idle blocks pressure is set to exactly zero without computing the power.
c = v × 1e18 / (1e18 + pressure) r = v − c
v is the eth sent. c walks the curve. r is surcharge. both enter the cistern. only c changes position and only c issues tokens. pressure one means half. pressure three means a quarter. pressure has no ceiling.