1 /*
2  * sys-emu - A system emulator for tutorials
3  * Copyright (C) 2018 - 2019 osdevelopment-info
4  *
5  * This program is free software: you can redistribute it and/or modify
6  * it under the terms of the GNU Affero General Public License as published by
7  * the Free Software Foundation, either version 3 of the License, or
8  * (at your option) any later version.
9  *
10  * This program is distributed in the hope that it will be useful,
11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13  * GNU Affero General Public License for more details.
14  *
15  * You should have received a copy of the GNU Affero General Public License
16  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
17  */
18 package info.osdevelopment.sysemu.memory
19 
20 import info.osdevelopment.sysemu.support.Utilities._
21 import scala.util.{Failure, Success, Try}
22 
23 /**
24   * The object CombinedReadWriteMemory used to create instances of the memory. The maximum memory that can be handled is
25   * 1 EiB.
26   */
27 object CombinedReadWriteMemory {
28 
29   /**
30     * Creates a read-write memory with the given `size`.
31     * @param size the size of the memory
32     * @return a `Success` with the read-write memory with the given size or a `Failure`
33     */
34   def apply(size: Long): Try[CombinedReadWriteMemory] = {
35     if (size <= 0 | size > 1.Ei) Failure(new IllegalArgumentException("Max size supported is 1 EiB"))
36     else Try(new CombinedReadWriteMemory(size))
37   }
38 
39 }
40 
41 /**
42   * A read-write memory that can hold up to 2^60^ Bytes (1 EiB). Please note that the size is immediately allocated.
43   * @param size the size of the read-write memory to create
44   */
45 class CombinedReadWriteMemory private(val size: Long) extends ReadWriteMemory {
46 
47   /** The size of the last "memory module". */
48   private val remaining = size % 1.Gi
49   /** The number of modules needed to create the memory. */
50   private val numberModules = (if (remaining == 0) size / 1.Gi else size / 1.Gi + 1).asInstanceOf[Int]
51   /** The modules for the memory. */
52   private val modules = Array
53     .fill(numberModules){ SimpleReadWriteMemory(1.Gi.asInstanceOf[Int]) }
54     .collect{ case Success(m) => m}
55   if (modules.length != numberModules) {
56     throw new IllegalStateException("Cannot create ReadWriteMemory")
57   }
58 
59   /**
60     * The read method to read the value from the array of arrays.
61     * @param address the address to read
62     * @return a `Success` with the byte read at the given address or a `Failure`
63     */
64   protected override def doRead(address: Long): Try[Byte] = {
65     val module = address / 1.Gi
66     val offset = address % 1.Gi
67     modules(module.asInstanceOf[Int]).readByte(offset)
68   }
69 
70   /**
71     * The write method to write the value to the array.
72     * @param address the address to write
73     * @param value the `value` to write
74     * @return a `Success` if the write was successful, `Failure` otherwise
75     */
76   protected override def doWrite(address: Long, value: Byte): Try[Unit] = {
77     val module = address / 1.Gi
78     val offset = address % 1.Gi
79     modules(module.asInstanceOf[Int]).writeByte(offset.asInstanceOf[Int], value)
80   }
81 
82 }