JBE的转移条件是CF=1或AF=1.
xor ax,ax
cmp ax,0;[ax=0,所以有下面的看法]
jbe ***
因为ax＝0，所以没有借位，所以CF＝0
AF是辅助，再两位减时，也没有借位，所以AF＝0。
那么是不是就应该说，没有满足条件，就不跳了？？？
但是JBE翻译过来，又是小于或者等于就跳。因为满足等于，所以就跳。
当然实事上是跳，但是从上面的标志寄存器上分析，是不是就不应该跳呢？？？
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还是从含义上去理解吧，小于等于则跳转。
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做了一下实验，CF=0，ZF=1
应该是书上错了
jbe=jump if below or equal
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Topic: Jump Conditions
Opcode Mnemonic Flags Checked Description
----------------------------------------------------------------------------
size 0010 JB/JNAE CF=1 Jump if below/not above or
equal (unsigned comparisons)
size 0011 JAE/JNB CF=0 Jump if above or equal/not
below (unsigned comparisons)
size 0110 JBE/JNA CF=1 or ZF=1 Jump if below or equal/not
above (unsigned comparisons)
size 0111 JA/JNBE CF=0 and ZF=0 Jump if above/not below or
equal (unsigned comparisons)
size 0100 JE/JZ ZF=1 Jump if equal (zero)
size 0101 JNE/JNZ ZF=0 Jump if not equal (not zero)
size 1100 JL/JNGE SF <> OF Jump if less/not greater or
equal (signed comparisons)
size 1101 JGE/JNL SF=OF Jump if greater or equal/not
less (signed comparisons)
size 1110 JLE/JNG ZF=1 or SF <> OF Jump if less or equal/not
greater (signed comparisons)
size 1111 JG/JNLE ZF=0 and SF=OF Jump if greater/not less or
equal (signed comparisons)
size 1000 JS SF=1 Jump if sign
size 1001 JNS SF=0 Jump if not sign
size 0010 JC CF=1 Jump if carry
size 0011 JNC CF=0 Jump if not carry
size 0000 JO OF=1 Jump if overflow
size 0001 JNO OF=0 Jump if not overflow
size 1010 JP/JPE PF=1 Jump if parity/parity even
size 1011 JNP/JPO PF=0 Jump if no parity/parity odd
----------------------------------------------------------------------------
NOTE: The size bits are 0111 for short jumps or 1000 for 80386/486
near jumps.