diff options
| author | Yuchen Pei <me@ypei.me> | 2018-01-20 15:41:49 +0100 |
|---|---|---|
| committer | Yuchen Pei <me@ypei.me> | 2018-01-20 15:41:49 +0100 |
| commit | d3a0cc3a8ba6dfeb64d3faeffdeb6845b60e5840 (patch) | |
| tree | d58df9ec2480e2a9ec6240f9c797f83d1a0b1056 /projects/12/Math.jack | |
| parent | 3571f998b28fbc8d9250ba04c983935f10a16c15 (diff) | |
rearranged the dir for github
- removed tools and pdfs
- rearranged the projects dirs
- added md files
- other minor changes
Diffstat (limited to 'projects/12/Math.jack')
| -rw-r--r-- | projects/12/Math.jack | 158 |
1 files changed, 0 insertions, 158 deletions
diff --git a/projects/12/Math.jack b/projects/12/Math.jack deleted file mode 100644 index 01bce8f..0000000 --- a/projects/12/Math.jack +++ /dev/null @@ -1,158 +0,0 @@ -// 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/12/Math.jack
-
-/**
- * A library of commonly used mathematical functions.
- * Note: Jack compilers implement multiplication and division using OS method calls.
- */
-class Math {
- static Array twoToThe;
-
- /** Initializes the library. */
- function void init() {
- var int i, x;
- let x = 1;
- let i = 0;
- let twoToThe = Array.new(16);
- while (i < 16){
- let twoToThe[i] = x;
- let x = x + x;
- let i = i + 1;
- }
- return;
- }
-
- function boolean bit(int x, int i) {
- return ~(x & twoToThe[i] = 0);
- }
-
- function int sign(int x) {
- if (x > 0) {
- return 1;
- } else {
- if (x < 0) {
- return -1;
- } else {
- return 0;
- }
- }
- }
-
- /** Returns the absolute value of x. */
- function int abs(int x) {
- if (x > 0){
- return x;
- } else {
- return -x;
- }
- }
-
- /** Returns the product of x and y.
- * When a Jack compiler detects the multiplication operator '*' in the
- * program's code, it handles it by invoking this method. In other words,
- * the Jack expressions x*y and multiply(x,y) return the same value.
- */
- function int multiply(int x, int y) {
- var int res, shiftedX, i;
- let shiftedX = x;
- let i = 0;
- let res = 0;
- //while ((~(twoToThe[i] > y)) & (i < 16)) {
- while (i < 16) {
- if (Math.bit(y, i)){
- let res = res + shiftedX;
- }
- let shiftedX = shiftedX + shiftedX;
- let i = i + 1;
- }
- return res;
- }
-
- /** Returns the integer part of x/y.
- * When a Jack compiler detects the multiplication operator '/' in the
- * program's code, it handles it by invoking this method. In other words,
- * the Jack expressions x/y and divide(x,y) return the same value.
- */
- function int divide(int x, int y) {
- var int ax, ay;
- if (x > 0) {
- if (y > 0) {
- return Math.divide1(x, y);
- } else {
- return -Math.divide1(x, -y);
- }
- } else {
- if (y > 0) {
- return -Math.divide1(-x, y);
- } else {
- return Math.divide1(-x, -y);
- }
- }
- }
-
- function int divide1(int x, int y) {
- var int q;
- if (y = 0) {
- do Output.printString("Error: division by zero.");
- do Sys.error(0);
- }
- if ((y > x) | (y < 0)) {
- return 0;
- }
- let q = Math.divide1(x, y * 2);
- if (x - (2 * q * y) < y) {
- return 2 * q;
- } else {
- return 2 * q + 1;
- }
- }
-
- function int length(int x){
- var int n;
- let n = 14;
- while (twoToThe[n] > x){
- let n = n - 1;
- }
- return n;
- }
-
- /** Returns the integer part of the square root of x. */
- function int sqrt(int x) {
- var int y, k, z, w;
- if (x < 0) {
- do Output.printString("Error: square rooting a negative number.");
- do Sys.error(0);
- }
- let k = Math.length(x) / 2;
- let y = 0;
- while (~(k < 0)) {
- let z = y + twoToThe[k];
- let w = z * z;
- if ((~(w > x)) & (w > 0)) {
- let y = z;
- }
- let k = k - 1;
- }
- return y;
- }
-
- /** Returns the greater number. */
- function int max(int a, int b) {
- if (a > b) {
- return a;
- } else {
- return b;
- }
- }
-
- /** Returns the smaller number. */
- function int min(int a, int b) {
- if (a < b) {
- return a;
- } else {
- return b;
- }
- }
-}
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