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| author | Frederick Yin <fkfd@fkfd.me> | 2022-08-16 11:54:23 +0800 |
|---|---|---|
| committer | Frederick Yin <fkfd@fkfd.me> | 2022-08-16 11:54:23 +0800 |
| commit | 9542deeb483a00b6fabed7574720926ce97d7511 (patch) | |
| tree | 0f2c1f72c03dd4693fd59df67544d2a4dddc5494 /projects/08/FunctionCalls/FibonacciElement/Main.vm | |
| parent | 9c0cb1d1c32724fc95ac9548e4f8d873d3adaccc (diff) | |
Projects, 01-06 completed
Diffstat (limited to 'projects/08/FunctionCalls/FibonacciElement/Main.vm')
| -rw-r--r-- | projects/08/FunctionCalls/FibonacciElement/Main.vm | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/projects/08/FunctionCalls/FibonacciElement/Main.vm b/projects/08/FunctionCalls/FibonacciElement/Main.vm new file mode 100644 index 0000000..55e5ad2 --- /dev/null +++ b/projects/08/FunctionCalls/FibonacciElement/Main.vm @@ -0,0 +1,30 @@ +// 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
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