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, Try}
22 
23 /**
24   * The object SimpleReadWriteMemory used to create instances of the memory. The maximum memory that can be handled is
25   * 1 GiB.
26   */
27 object SimpleReadWriteMemory {
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
33     */
34   def apply(size: Long): Try[SimpleReadWriteMemory] = {
35     if (size <= 0 | size > 1.Gi) Failure(new IllegalArgumentException("Max size supported is 1 GiB"))
36     else Try(new SimpleReadWriteMemory(size))
37   }
38 
39 }
40 
41 /**
42   * A read-write memory (aka RAM) with the given `size`. The maximum size is 2^30^ Bytes (1 GiB). The memory is backed
43   * by an array.
44   * @param size the size of the memory
45   */
46 class SimpleReadWriteMemory private(val size: Long) extends ReadWriteMemory {
47 
48   /** The array to hold the memory data. */
49   val memory = new Array[Byte](size.asInstanceOf[Int])
50 
51   /**
52     * The read method to read the value from the array.
53     * @param address the address to read
54     * @return a `Success` with the byte read at the given address
55     */
56   protected override def doRead(address: Long): Try[Byte] = {
57     Try(memory(address.asInstanceOf[Int]))
58   }
59 
60   /**
61     * The write method to write the value to the array.
62     * @param address the address to write
63     * @param value the `value` to write
64     * @return a `Success` when the byte is written successfully, `Failure` otherwise
65     */
66   protected override def doWrite(address: Long, value: Byte): Try[Unit] = {
67     Try(memory(address.asInstanceOf[Int]) = value)
68   }
69 
70 }