// SolveBlock takes a block, target, and number of iterations as input and
// tries to find a block that meets the target. This function can take a long
// time to complete, and should not be called with a lock.
func (m *Miner) SolveBlock(b types.Block, target types.Target) (types.Block, bool) {
// Assemble the header.
merkleRoot := b.MerkleRoot()
header := make([]byte, 80)
copy(header, b.ParentID[:])
binary.LittleEndian.PutUint64(header[40:48], uint64(b.Timestamp))
copy(header[48:], merkleRoot[:])
nonce := (*uint64)(unsafe.Pointer(&header[32]))
for i := 0; i < iterationsPerAttempt; i++ {
id := crypto.HashBytes(header)
if bytes.Compare(target[:], id[:]) >= 0 {
copy(b.Nonce[:], header[32:40])
return b, true
}
*nonce++
}
return b, false
}