QkoSad
64 lines
1.9 KiB
Plaintext
Executable File
64 lines
1.9 KiB
Plaintext
Executable File
// This file is part of www.nand2tetris.org
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// and the book "The Elements of Computing Systems"
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// by Nisan and Schocken, MIT Press.
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// File name: projects/12/Memory.jack
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/**
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* This library provides two services: direct access to the computer's main
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* memory (RAM), and allocation and recycling of memory blocks. The Hack RAM
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* consists of 32,768 words, each holding a 16-bit binary number.
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*/
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class Memory {
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static Array mem;
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/** Initializes the class. */
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function void init() {
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let mem = 0;
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let mem[2048] = 14334;
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let mem[2049] = -1;
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return;
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}
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/** Returns the RAM value at the given address. */
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function int peek(int address) {
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return mem[address];
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}
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/** Sets the RAM value at the given address to the given value. */
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function void poke(int address, int value) {
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let mem[address] = value;
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return;
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}
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/** Finds an available RAM block of the given size and returns
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* a reference to its base address. */
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function int alloc(int size) {
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var Array current_block;
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var int tmp;
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let current_block = 2048;
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if (size < 0){
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do Sys.error(5);
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}
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if (size = 0){
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let size = 1;
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}
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while (current_block[0] < (size + 2)) {
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let current_block = current_block[1];
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}
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let current_block[0] = current_block[0] - size - 2;
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let current_block = current_block + current_block[0] + 2;
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let current_block[0] = size;
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return current_block + 2;
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}
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/** De-allocates the given object (cast as an array) by making
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* it available for future allocations. */
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function void deAlloc(Array o) {
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var Array current_block;
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let current_block = 2048;
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let o[1]= current_block[1];
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let current_block[1] = o;
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return;
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}
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}
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