Branch Instructions

Branch instructions are used to implement IF statements and loops in assembly language.

An unconditional branch instruction executes by assigning the value of label to the PC. Program execution continues with the instruction located at label.

Unconditional Branch

A conditional branch instruction tests a condition. If the condition is true, the PC is reset to label. If the condition is false, the branch instruction executes a no-op.

Zero Tests

Relational Tests

Notes:

x and y may be type integer or character and may be variables or constants.

All branch instructions can be constructed using branch on zero.

Redundant branch instructions are included for convenience.

Examples:

1. b next
   
   is equivalent to
   
   beqz 0, next
   
   
2. beq x, y, equal
   
   can be written as:
   
   sub t, x, y
   beqz t, equal
   
   
3. blt x, y, label
   
   is the same as:
   
   bge y, x, label