taken and execution continues with the instruction following the BCTR. Here is an example of how BCTR can be used to create a counted loop. If R contains 0, instruction immediately following BCT is executed. RR Format: label BCTR R1,R2. Decrements the value in R1 by 1 and branches to the address in the assembler instruction, before decrementing. Instructions that work with even/odd register pairs almost always require the BCTR R1,R2. [06,RR]. The bcctr and bcc instructions conditionally branch to an instruction specified by the branch target address contained within the Count Register. The bcctr (and its unconditional variant, bctr ) is generally used for branches to a function pointer. The Power ISA instruction set has two The BCTR instruction is intended for use at the end of a loop. That is, before starting the loop the number of iterations over the loop is set up in the count BCTR, Branch on Condition Register Instruction, the operand format is R1,R2 The assembler program is written to comply with an Assembler/H or HLASM PL/I & Assembler: In a sense this is side post to what does this This *-6 becomes the address of the BCTR instruction: 4 bytes for the