nand2tetris/projects/08/FunctionCalls/NestedCall/Sys.vm

// Sys.vm for NestedCall test.

// Sys.init()
//
// Calls Sys.main() and stores return value in temp 1.
// Does not return.  (Enters infinite loop.)

function Sys.init 0 // L1
push constant 4000	// test THIS and THAT context save
pop pointer 0 // L3
push constant 5000
pop pointer 1 // L5
call Sys.main 0
pop temp 1  // L7
label LOOP
goto LOOP  // L9

// Sys.main()
//
// Sets locals 1, 2 and 3, leaving locals 0 and 4 unchanged to test
// default local initialization to 0.  (RAM set to -1 by test setup.)
// Calls Sys.add12(123) and stores return value (135) in temp 0.
// Returns local 0 + local 1 + local 2 + local 3 + local 4 (456) to confirm
// that locals were not mangled by function call.

function Sys.main 5  // L10
push constant 4001
pop pointer 0
push constant 5001  // L13
pop pointer 1
push constant 200  // L15
pop local 1
push constant 40 // L17
pop local 2
push constant 6 // L19
pop local 3
push constant 123
call Sys.add12 1  // L22
pop temp 0
push local 0  // L24
push local 1
push local 2
push local 3  // L27
push local 4
add
add  // L30
add
add // L32
return  // L33

// Sys.add12(int n)
//
// Returns n+12.

function Sys.add12 0 // L34
push constant 4002
pop pointer 0
push constant 5002 // L37
pop pointer 1
push argument 0
push constant 12 // L40
add
return // L42