ARM Assembler – How do I use CMP, BLT and BGT?

You cannot do a conditional branch without first setting the condition register somehow. This can be done with cmp or by adding s to most instructions. Check out the ARM assembly documentation for details. Quick example:

Branch if r0 greater than 5:

cmp r0, #5 ;Performs r0-5 and sets condition register
bgt label_foo ;Branches to label_foo if condition register is set to GT

Compare r6 with r4 , put difference into r7, branch if r7 < 0:

subs r7, r6, r4 ;Performs r7 = r6 - r4 and sets condition register
blt label_bar ;Branches to label_bar if r7 < 0 (in which case r6 < r4)

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