Adjustment Interval (#1075)

Cleaned up presentation code and added adjustment interval getter to base interface

EIPS/eip-918.md

@@ -26,9 +26,11 @@ Token distribution via the ICO model and it's derivatives is susceptable to illi
 The general behavioral specification includes a primary function that defines the token minting operation, an optional merged minting operation for issuing multiple tokens, getters for challenge number, mining difficulty, mining target and current reward, and finally a Mint event, to be emitted upon successful solution validation and token issuance. At a minimum, contracts must adhere to this interface (save the optional merge operation). It is recommended that contracts interface with the more behaviorally defined Abstract Contract described below, in order to leverage a more defined construct, allowing for easier external implementations via overridden phased functions. (see 'Abstract Contract' below)
 
 ``` js
-interface EIP918Interface  {
+contract EIP918Interface  {
 
     function mint(uint256 nonce, bytes32 challenge_digest) public returns (bool success);
+
+    function getAdjustmentInterval() public view returns (uint);
 
     function getChallengeNumber() public constant returns (bytes32);
 
@@ -38,10 +40,10 @@ interface EIP918Interface  {
 
     function getMiningReward() public constant returns (uint);
 
-    event Mint(address indexed from, uint reward_amount, uint epochCount, bytes32 newChallengeNumber);
-
     // Optional
-    function merge(uint256 nonce, bytes32 challenge_digest, address[] mineTokens) public returns (bool success);
+    function merge(uint256 nonce, bytes32 challenge_digest, address[] mineTokens) public returns (bool success){}
+
+    event Mint(address indexed from, uint reward_amount, uint epochCount, bytes32 newChallengeNumber);
 
 }
 ```
@@ -86,7 +88,10 @@ populate statistics, mutate epoch variables and adjust the solution difficulty a
 a Mint event is emitted before returning a boolean success flag.
 
 ``` js
- contract AbstractERC918 is EIP918Interface {
+contract AbstractERC918 is EIP918Interface {
+
+    // the amount of time between difficulty adjustments
+    uint public adjustmentInterval = 10 minutes;
 
     // generate a new challenge number after a new reward is minted
     bytes32 public challengeNumber;
@@ -97,21 +102,12 @@ a Mint event is emitted before returning a boolean success flag.
     // cumulative counter of the total minted tokens
     uint public tokensMinted;
 
-    // number of blocks per difficulty adjustment
+    // number of blocks per difficulty readjustment
     uint public blocksPerReadjustment;
 
-    uint public epochCount;//number of 'blocks' mined
-
-    // track read only minting statistics
-    struct Statistics {
-        address lastRewardTo;
-        uint lastRewardAmount;
-        uint lastRewardEthBlockNumber;
-        uint lastRewardTimestamp;
-    }
-
-    Statistics public statistics;
-
+    //number of 'blocks' mined
+    uint public epochCount;
+
     /*
      * Externally facing mint function that is called by miners to validate challenge digests, calculate reward,
      * populate statistics, mutate epoch variables and adjust the solution difficulty as required. Once complete,
@@ -129,15 +125,12 @@ a Mint event is emitted before returning a boolean success flag.
         // increment the minted tokens amount
         tokensMinted += rewardAmount;
 
-        uint epochCount = _epoch();
+        epochCount = _epoch();
 
         //every so often, readjust difficulty. Dont readjust when deploying
         if(epochCount % blocksPerReadjustment == 0){
             _adjustDifficulty();
         }
-
-         //populate read only diagnostics data
-        statistics = Statistics(msg.sender, rewardAmount, block.number, now);
 
         // send Mint event indicating a successful implementation
         emit Mint(msg.sender, rewardAmount, epochCount, challengeNumber);
@@ -222,12 +215,20 @@ Internal interface function \_adjustDifficulty, meant to be overridden in implem
 function _adjustDifficulty() internal returns (uint);
 ```
 
+#### getAdjustmentInterval
+
+The amount of time, in seconds, between difficulty adjustment operations.
+
+``` js
+function getAdjustmentInterval() public view returns (uint);
+```
+
 #### getChallengeNumber
 
 Recent ethereum block hash, used to prevent pre-mining future blocks.
 
 ``` js
-function getChallengeNumber() public constant returns (bytes32) 
+function getChallengeNumber() public view returns (bytes32);
 ```
 
 #### getMiningDifficulty
@@ -236,15 +237,15 @@ The number of digits that the digest of the PoW solution requires which typicall
 
 
 ``` js
-function getMiningDifficulty() public constant returns (uint)
+function getMiningDifficulty() public view returns (uint)
 ```
 
 #### getMiningReward
 
 Return the current reward amount. Depending on the algorithm, typically rewards are divided every reward era as tokens are mined to provide scarcity.
 
 ``` js
-function getMiningReward() public constant returns (uint)
+function getMiningReward() public view returns (uint)
 ```
 
 ### Example mining function
@@ -280,7 +281,6 @@ Backwards incompatibilities are not introduced.
 ### Implementation
 
 Simple Example:
-
 https://github.com/0xbitcoin/EIP918-Mineable-Token/blob/master/contracts/SimpleERC918.sol
 
 Complex Examples: