example files

Test-Files/FibonacciElement/FibonacciElement.cmp

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+| RAM[0] |RAM[261]|
+|    262 |      3 |

Test-Files/FibonacciElement/FibonacciElement.tst

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+// 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/08/FunctionCalls/FibonacciElement/FibonacciElement.tst
+
+// FibonacciElement.asm results from translating both Main.vm and Sys.vm into
+// a single assembly program, stored in the file FibonacciElement.asm.
+
+load FibonacciElement.asm,
+output-file FibonacciElement.out,
+compare-to FibonacciElement.cmp,
+output-list RAM[0]%D1.6.1 RAM[261]%D1.6.1;
+
+repeat 6000 {
+  ticktock;
+}
+
+output;

Test-Files/FibonacciElement/FibonacciElementVME.tst

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+// 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/08/FunctionCalls/FibonacciElement/FibonacciElementVME.tst
+
+load,  // Load all the VM files from the current directory
+output-file FibonacciElement.out,
+compare-to FibonacciElement.cmp,
+output-list RAM[0]%D1.6.1 RAM[261]%D1.6.1;
+
+set sp 261,
+
+repeat 110 {
+  vmstep;
+}
+
+output;

Test-Files/FibonacciElement/Main.vm

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+// 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/08/FunctionCalls/FibonacciElement/Main.vm
+
+// Computes the n'th element of the Fibonacci series, recursively.
+// n is given in argument[0].  Called by the Sys.init function 
+// (part of the Sys.vm file), which also pushes the argument[0] 
+// parameter before this code starts running.
+
+function Main.fibonacci 0
+push argument 0
+push constant 2
+lt                     // checks if n<2
+if-goto IF_TRUE
+goto IF_FALSE
+label IF_TRUE          // if n<2, return n
+push argument 0        
+return
+label IF_FALSE         // if n>=2, returns fib(n-2)+fib(n-1)
+push argument 0
+push constant 2
+sub
+call Main.fibonacci 1  // computes fib(n-2)
+push argument 0
+push constant 1
+sub
+call Main.fibonacci 1  // computes fib(n-1)
+add                    // returns fib(n-1) + fib(n-2)
+return

Test-Files/FibonacciElement/Sys.vm

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+// 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/08/FunctionCalls/FibonacciElement/Sys.vm
+
+// Pushes a constant, say n, onto the stack, and calls the Main.fibonacii
+// function, which computes the n'th element of the Fibonacci series.
+// Note that by convention, the Sys.init function is called "automatically" 
+// by the bootstrap code.
+
+
+function Sys.init 0
+push constant 4
+call Main.fibonacci 1   // computes the 4'th fibonacci element
+label WHILE
+goto WHILE              // loops infinitely