From a000308104aab27c2dde9a306f1bc654b2db4806 Mon Sep 17 00:00:00 2001 From: Yuchen Pei Date: Wed, 29 Nov 2017 12:30:41 +0100 Subject: first commit --- projects/11/ConvertToBin/Main.jack | 82 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 82 insertions(+) create mode 100644 projects/11/ConvertToBin/Main.jack (limited to 'projects/11/ConvertToBin') diff --git a/projects/11/ConvertToBin/Main.jack b/projects/11/ConvertToBin/Main.jack new file mode 100644 index 0000000..e627486 --- /dev/null +++ b/projects/11/ConvertToBin/Main.jack @@ -0,0 +1,82 @@ +// This file is part of www.nand2tetris.org +// and the book "The Elements of Computing Systems" +// by Nisan and Schocken, MIT Press. +// File name: projects/11/ConvertToBin/Main.jack + +/** + * Unpacks a 16-bit number into its binary representation: + * Takes the 16-bit number stored in RAM[8000] and stores its individual + * bits in RAM[8001..8016] (each location will contain 0 or 1). + * Before the conversion, RAM[8001]..RAM[8016] are initialized to -1. + * + * The program should be tested as follows: + * 1) Load the program into the supplied VM emulator + * 2) Put some value in RAM[8000] + * 3) Switch to "no animation" + * 4) Run the program (give it enough time to run) + * 5) Stop the program + * 6) Check that RAM[8001]..RAM[8016] contains the correct binary result, and + * that none of these memory locations contains -1. + */ +class Main { + + /** + * Initializes RAM[8001]..RAM[8016] to -1, + * and converts the value in RAM[8000] to binary. + */ + function void main() { + var int value; + do Main.fillMemory(8001, 16, -1); // sets RAM[8001]..RAM[8016] to -1 + let value = Memory.peek(8000); // reads a value from RAM[8000] + do Main.convert(value); // performs the conversion + return; + } + + /** Converts the given decimal value to binary, and puts + * the resulting bits in RAM[8001]..RAM[8016]. */ + function void convert(int value) { + var int mask, position; + var boolean loop; + + let loop = true; + while (loop) { + let position = position + 1; + let mask = Main.nextMask(mask); + + if (~(position > 16)) { + + if (~((value & mask) = 0)) { + do Memory.poke(8000 + position, 1); + } + else { + do Memory.poke(8000 + position, 0); + } + } + else { + let loop = false; + } + } + return; + } + + /** Returns the next mask (the mask that should follow the given mask). */ + function int nextMask(int mask) { + if (mask = 0) { + return 1; + } + else { + return mask * 2; + } + } + + /** Fills 'length' consecutive memory locations with 'value', + * starting at 'startAddress'. */ + function void fillMemory(int startAddress, int length, int value) { + while (length > 0) { + do Memory.poke(startAddress, value); + let length = length - 1; + let startAddress = startAddress + 1; + } + return; + } +} -- cgit v1.2.3