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/09/Fraction/Fraction.jack | 65 ++++++++++++++++++++++++++++++++++++++ projects/09/Fraction/Main.jack | 16 ++++++++++ 2 files changed, 81 insertions(+) create mode 100644 projects/09/Fraction/Fraction.jack create mode 100644 projects/09/Fraction/Main.jack (limited to 'projects/09/Fraction') diff --git a/projects/09/Fraction/Fraction.jack b/projects/09/Fraction/Fraction.jack new file mode 100644 index 0000000..c86f0a5 --- /dev/null +++ b/projects/09/Fraction/Fraction.jack @@ -0,0 +1,65 @@ +// 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/09/Fraction/Fraction.jack + +/** Represents the Fraction type and related operations. */ +class Fraction { + field int numerator, denominator; // field = property = member variable. + + /** Constructs a (reduced) fraction from the given numerator and denominator. */ + constructor Fraction new(int x, int y) { + let numerator = x; + let denominator = y; + do reduce(); // reduces the fraction + return this; // a constructor is expected to return a reference to the new object + } + + // Reduces this fraction. + method void reduce() { + var int g; + let g = Fraction.gcd(numerator, denominator); + if (g > 1) { + let numerator = numerator / g; + let denominator = denominator / g; + } + return; + } + + /** Accessors. */ + method int getNumerator() { return numerator; } + method int getDenominator() { return denominator; } + + /** Returns the sum of this fraction and the other one. */ + method Fraction plus(Fraction other) { + var int sum; + let sum = (numerator * other.getDenominator()) + (other.getNumerator() * denominator); + return Fraction.new(sum, denominator * other.getDenominator()); + } + + // More fraction-related methods (minus, times, div, etc.) can be added here. + + /** Disposes this fraction. */ + method void dispose() { + do Memory.deAlloc(this); // uses an OS routine to recycle the memory held by the object + return; + } + + /** Prints this fraction in the format x/y. */ + method void print() { + do Output.printInt(numerator); + do Output.printString("/"); + do Output.printInt(denominator); + return; + } + + // Computes the greatest common divisor of the given integers. + function int gcd(int a, int b) { + var int r; + while (~(b = 0)) { // applies Euclid's algorithm + let r = a - (b * (a / b)); // r = remainder of the integer division a/b + let a = b; let b = r; + } + return a; + } +} diff --git a/projects/09/Fraction/Main.jack b/projects/09/Fraction/Main.jack new file mode 100644 index 0000000..43ddece --- /dev/null +++ b/projects/09/Fraction/Main.jack @@ -0,0 +1,16 @@ +// 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/09/Fraction/Main.jack + +// Computes the sum of 2/3 and 1/5. +class Main { + function void main() { + var Fraction a, b, c; + let a = Fraction.new(2,3); + let b = Fraction.new(1,5); + let c = a.plus(b); // Computes c = a + b + do c.print(); // Prints "13/15" + return; + } +} -- cgit v1.2.3