Control flow instructions

Control flow instructions are crucial in the assembly language for the Virtual Processor, directing the flow of execution within the program.

goto instruction

Syntax and usage

• Syntax: goto label1
• Function: Unconditionally jumps to the specified label.
• Binary code: 0000 1000 0101 0110 (label id)
• Error check: Ensure the label exists.

call instruction

Syntax and usage

• Syntax: call label1
• Function: Calls a subroutine located at label1.
• Binary code: 0001 0000 0101 0110 (label id)
• Error check: Verify the existence of the label.

ret instruction

Syntax and usage

• Syntax: ret
• Function: Returns from a subroutine to the calling point.
• Binary code: 1011 0000 0000 0000
• Error check: Use only after a call instruction.

Examples

1. Using goto:

   goto mainLoop   ; Jumps to the label 'mainLoop'
   

2. Calling a subroutine:

   call computeValue  ; Calls the subroutine 'computeValue'
   

3. Returning from a subroutine:

   ret  ; Returns control to the point after the last call