COMP1860 Lecture 3.1 Virtual Machines: Control

Flashcards covering branching and function commands in Hack VM language.

Branching Commands

Commands that define destinations, jump unconditionally, or jump based on a condition in the Hack VM language. Examples: label, goto, if-goto.

label

Defines a destination within the code for use with goto and if-goto commands. Syntax: label

goto

Jumps execution to the command immediately following the specified label. Syntax: goto

if-goto

Pops a condition from the stack. If true, jumps to the command after ; otherwise, continues to the next command. Syntax: if-goto

ReLU(x: int)

Returns x if x > 0, otherwise returns 0.

sumInt(n: int)

Calculates the sum of integers from 1 to n.

Function Commands

Commands used to define, call, and return from functions in the Hack VM language. Examples: function, call, return.

function

Declares a function with a given name and number of local variables. Syntax: function

call

Calls a function, specifying the function name and the number of arguments pushed onto the stack. Syntax: call . The caller must push values onto the stack first.

return

Returns control to the calling function. The callee must push the return value onto the stack before returning. Syntax: return