Module bitmap 

EVM-compatible uint256 bitmap operations and deterministic selection-group derivation.

Pure, anchor-free. Moved verbatim from the Molpha program’s utils/bitmap.rs (MolphaError → DataUpdateError).

Functions

bitmap_bit_set

Solidity uint256 layout: bit pos has weight 1 << pos, pos == 0 is the integer LSB.

bitmap_clear_bit

bitmap_is_subset

bitmap_is_subset_u256

sub ⊆ sup when both are already loaded as U256.

bitmap_load

EVM uint256 bitmap loaded from Solidity bytes32 (big-endian).

bitmap_popcount_evm

bitmap_set_bit

bitmap_store

Serialize an EVM uint256 bitmap to bytes32 for storage / hashing.

derive_group_bitmap

Port of NodeGroupBitmapLib.derive from the EVM reference.

effective_selection_size

Selection slot count: min(node_count, signatures_required + redundancy_buffer).

for_each_set_bit

Iterate set bit positions in ascending order (EVM signer order).

for_each_set_bit_u256

Visit set bits in ascending order; returns the peeled bitmap (zero when fully consumed).

get_index

Bitmap bit index of the signer at 0-based rank pos when signers are ordered by ascending bit index (same order as EVM Validator.verify combines pubkeys).

validate_bitmap_upper_bits_clear

validate_bitmap_upper_bits_clear_u256

Reject signers with bits outside [0, node_count).