TSK3000A Core Instruction - BGEZAL

Instruction:

Branch On Greater Than Or Equal To And Link

Assembler Format:

bgezal rA, target

Example:

bgezal $3, _myfunc

Description:

Generates a branch target address by adding the address of the instruction in the delay slot to a signed offset (a 16-bit immediate value, IMM16, calculated from the target operand, left-shifted two bits and sign-extended to 32 bits). The address of the instruction following the instruction in the delay slot is unconditionally placed in general purpose register r31 as the return address from the branch. If the sign bit of the value in GPR rA is 0 (i.e. the value is positive or 0), the program branches to the target address after a delay of one instruction cycle.

Operation:

If rA >= 0 Then
   PC <-- PC + 4 + SignExtend(IMM16 * 4)
   GPR[31] <-- PC + 8
Else
   PC <-- PC + 4

Instruction Type:

I-Type

Instruction Fields:

rA = Register index of operand A

target = a symbolic address label or a hard-coded PC-offset in bytes