Implement mining slow start with a linear ramp

src/consensus/params.h

@@ -14,6 +14,20 @@ namespace Consensus {
  */
 struct Params {
     uint256 hashGenesisBlock;
+    /** Needs to evenly divide MAX_SUBSIDY to avoid rounding errors. */
+    int nSubsidySlowStartInterval;
+    /**
+     * Shift based on a linear ramp for slow start:
+     *
+     * MAX_SUBSIDY*(t_s/2 + t/r) = MAX_SUBSIDY*t_h  Coin balance
+     *                 t_s + t_r = t_h + t_c        Block balance
+     *
+     * t_s = nSubsidySlowStartInterval
+     * t_r = number of blocks between end of slow start and first halving
+     * t_h = nSubsidyHalvingInterval
+     * t_c = SubsidySlowStartShift()
+     */
+    int SubsidySlowStartShift() const { return nSubsidySlowStartInterval / 2; }
     int nSubsidyHalvingInterval;
     /** Used to check majorities for block version upgrade */
     int nMajorityEnforceBlockUpgrade;