嵌入式汇编高手请进！！！

下面的程序啥意思呀，高手解释一下！！！谢谢
1：what value is stored in m in the following assembly language code　fragment if n=7?

LDAA #n

LABEL1: CMPA #5

BHI L3

BEQ L2

DECA

BRA L1

LABEL2: CLRA

LABEL3: STAA #m

2：Assume the BC register value is 8538H, and the DE register　value is 62A5H.Find the value of register BC after the following　assembly operations:

MOV A,C

SUB E

MOV C,A

MOV A,B

SBB D

MOV B,A

3：In the Assembly code shown below

LOOP: MVI C,78H

DCR C

JNZ LOOP

HLT

How many times is the DCR C Operation executed?