Instruction Syntax

Mnemonic	Format	Flags
beqlr		LK = 0
beqlrl		LK = 1

Instruction Encoding

Field	Bits	Description
Primary Opcode	0-5	010011 (0x13)
BO	6-10	01010 (Branch Option)
BI	11-15	00000 (Branch Input - CR0[EQ])
BD	16-29	00000000000000 (unused)
LK	31	Link bit

Operation

if CR0[EQ] = 1 then
    NIA ← LR
if LK = 1 then
    LR ← CIA + 4

BEQLR branches to the address stored in the Link Register if the Equal (EQ) bit in Condition Register field 0 is set.

1. Checks if the Equal bit (EQ) in CR0 is set
2. If equal, branches to the address in LR
3. Optionally saves the return address in LR if LK=1

Note: BEQLR is a derived form of the BCLR (Branch Conditional to Link Register) instruction with BO=01010 and BI=00000.

Affected Registers

Link Register (LR)

(if LK = 1)

• LR - Set to CIA + 4 (return address)

Next Instruction Address (NIA)

• NIA - Set to LR if condition is met

Examples

Conditional Function Return

# Return from function if condition is met
cmpwi r3, 0           # Check return value
beqlr                 # Return if r3 == 0
# Continue execution if condition not met
# ... more code ...
blr                   # Unconditional return

Early Exit from Function

# Exit function early if error condition
cmpwi r3, -1          # Check for error code
beqlr                 # Return immediately if error
# Process normal case
# ... normal processing ...
blr                   # Normal return

Validation and Return

# Validate input and return if invalid
cmpwi r3, 0           # Check if input is zero
beqlr                 # Return if input is zero (invalid)
# Process valid input
# ... processing ...
blr                   # Return after processing

Loop Exit Condition

# Exit loop if condition met
loop_start:
# ... loop body ...
cmpwi r3, 0           # Check exit condition
beqlr                 # Return if condition met
# Continue loop
b loop_start

Error Handling with Return

# Handle different error conditions
cmpwi r3, 1           # Check for error type 1
beqlr                 # Return if error type 1
cmpwi r3, 2           # Check for error type 2
beqlr                 # Return if error type 2
# Handle normal case
# ... normal processing ...
blr                   # Normal return

Recursive Function Exit

# Recursive function with early exit
recursive_function:
cmpwi r3, 1           # Check base case
beqlr                 # Return if base case reached
# Recursive case
# ... recursive processing ...
subi r3, r3, 1        # Decrement counter
bl recursive_function # Recursive call
blr                   # Return from recursive call

Related Instructions

bclr (Branch Conditional to Link Register), blr (Branch to Link Register)