Merge pull request #5 from ralexstokes/4788-change-modulus-name

change name of length of the EIP-4788 ring buffer

EIPS/eip-4788.md

@@ -29,7 +29,7 @@ restaking constructions, smart contract bridges, MEV mitigations and more.
 | constants                    | value                                        |
 |---                           |---                                           |
 | `FORK_TIMESTAMP`             | TBD                                          |
-| `HISTORICAL_ROOTS_MODULUS`   | `98304`                                      |
+| `HISTORY_BUFFER_LENGTH`      | `98304`                                      |
 | `SYSTEM_ADDRESS`             | `0xfffffffffffffffffffffffffffffffffffffffe` |
 | `BEACON_ROOTS_ADDRESS`       | `0xbEac00dDB15f3B6d645C48263dC93862413A222D` |
 
@@ -87,15 +87,15 @@ The beacon roots contract has two operations: `get` and `set`. The input itself
 
 * Callers provide the `timestamp` they are querying encoded as 32 bytes in big-endian format.
 * If the input is not exactly 32 bytes, the contract must revert.
-* Given `timestamp`, the contract computes the storage index in which the timestamp is stored by computing the modulo `timestamp % HISTORICAL_ROOTS_MODULUS` and reads the value.
+* Given `timestamp`, the contract computes the storage index in which the timestamp is stored by computing the modulo `timestamp % HISTORY_BUFFER_LENGTH` and reads the value.
 * If the `timestamp` does not match, the contract must revert.
-* Finally, the beacon root associated with the timestamp is returned to the user. It is stored at `timestamp % HISTORICAL_ROOTS_MODULUS + HISTORICAL_ROOTS_MODULUS`.
+* Finally, the beacon root associated with the timestamp is returned to the user. It is stored at `timestamp % HISTORY_BUFFER_LENGTH + HISTORY_BUFFER_LENGTH`.
 
 ##### `set`
 
 * Caller provides the parent beacon block root as calldata to the contract.
-* Set the storage value at `header.timestamp % HISTORICAL_ROOTS_MODULUS` to be `header.timestamp`
-* Set the storage value at `header.timestamp % HISTORICAL_ROOTS_MODULUS + HISTORICAL_ROOTS_MODULUS` to be `calldata[0:32]`
+* Set the storage value at `header.timestamp % HISTORY_BUFFER_LENGTH` to be `header.timestamp`
+* Set the storage value at `header.timestamp % HISTORY_BUFFER_LENGTH + HISTORY_BUFFER_LENGTH` to be `calldata[0:32]`
 
 ##### Pseudocode
 
@@ -109,20 +109,20 @@ def get():
     if len(evm.calldata) != 32:
         evm.revert()
 
-    timestamp_idx = to_uint256_be(evm.calldata) % HISTORICAL_ROOTS_MODULUS
+    timestamp_idx = to_uint256_be(evm.calldata) % HISTORY_BUFFER_LENGTH
     timestamp = storage.get(timestamp_idx)
 
     if timestamp != evm.calldata:
         evm.revert()
 
-    root_idx = timestamp_idx + HISTORICAL_ROOTS_MODULUS
+    root_idx = timestamp_idx + HISTORY_BUFFER_LENGTH
     root = storage.get(root_idx)
 
     evm.return(root)
 
 def set():
-    timestamp_idx = to_uint256_be(evm.timestamp) % HISTORICAL_ROOTS_MODULUS
-    root_idx = timestamp_idx + HISTORICAL_ROOTS_MODULUS
+    timestamp_idx = to_uint256_be(evm.timestamp) % HISTORY_BUFFER_LENGTH
+    root_idx = timestamp_idx + HISTORY_BUFFER_LENGTH
 
     storage.set(timestamp_idx, evm.timestamp)
     storage.set(root_idx, evm.calldata)
@@ -260,7 +260,7 @@ e.g. with a singleton state root contract that caches the proof per slot).
 
 ### Why two ring buffers?
 
-The first ring buffer only tracks `HISTORICAL_ROOTS_MODULUS` worth of roots and so for all possible timestamp values would consume a constant amount of storage.
+The first ring buffer only tracks `HISTORY_BUFFER_LENGTH` worth of roots and so for all possible timestamp values would consume a constant amount of storage.
 However, this design opens the precompile to an attack where a skipped slot that has the same value modulo the ring buffer length would return an old root value,
 rather than the most recent one.