digishield_pattern2

from base ltc

    def get_target_dgsld(self, height, chain=None):

        # Litecoin: go back the full period unless it's the first retarget
        if chain is None:
            chain = {}

        nTargetTimespan = 95040 #1.1 days 1.1*24*60*60

        nTargetSpacing = 1.5 * 60 #1.5 minute
        nTargetSpacingDigisheld = 1.5 * 60 #1.5 minute
        nIntervalDigisheld = nTargetSpacingDigisheld // nTargetSpacing #1

        nAdjustmentInterval = nIntervalDigisheld #1

        blockstogoback = nAdjustmentInterval - 1 #0
        if (height != nAdjustmentInterval):
            blockstogoback = nAdjustmentInterval

        latest_retarget_height = (height // nAdjustmentInterval) * nAdjustmentInterval
        last_height = latest_retarget_height - 1
        first_height = last_height - blockstogoback #- 301
        first = chain.get(first_height)
        if first is None:
            first = self.read_header(first_height)
        last = chain.get(last_height)
        if last is None:
            last = self.read_header(last_height)

        # bits to target
        bits = last.get('bits')
        bitsN = (bits >> 24) & 0xff
        if not (bitsN >= 0x03 and bitsN <= 0x1e):
            raise BaseException("First part of bits should be in [0x03, 0x1e]")
        bitsBase = bits & 0xffffff
        if not (bitsBase >= 0x8000 and bitsBase <= 0x7fffff):
            raise BaseException("Second part of bits should be in [0x8000, 0x7fffff]")
        target = bitsBase << (8 * (bitsN-3))
        if height % nAdjustmentInterval != 0:
            return bits, target
        # new target
        nActualTimespan = last.get('timestamp') - first.get('timestamp')
        nActualTimespan = nTargetTimespan + int(float(nActualTimespan - nTargetTimespan) / float(8))
        nActualTimespan = max(nActualTimespan, nTargetTimespan - int(float(nTargetTimespan) / float(4)))
        nActualTimespan = min(nActualTimespan, nTargetTimespan + int(float(nTargetTimespan) / float(2)))
        new_target = min(MAX_TARGET, (target*nActualTimespan) // nTargetTimespan)
        # convert new target to bits
        c = ("%064x" % int(new_target))[2:]
        while c[:2] == '00' and len(c) > 6:
            c = c[2:]
        bitsN, bitsBase = len(c) // 2, int('0x' + c[:6], 16)
        if bitsBase >= 0x800000:
            bitsN += 1
            bitsBase >>= 8
        new_bits = bitsN << 24 | bitsBase
        return new_bits, bitsBase << (8 * (bitsN-3))