ARM condition code

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大部分的arm指令可以条件执行，也就是可以根据状态寄存器中的值的情况条件执行。

下面是condition code的列表

Opcode[31:28]   Mnemonic extension    Meaning                          Condition flag state
0000                    EQ                             Equal                                                     Z set
0001                    NE                             Not equal                                               Z clear
0010                    CS/HS                       Carry set/unsigned higher or same        C set
0011                    CC/LO                       Carry clear/unsigned lower                    C clear
0100                    MI                             Minus/negative                                       N set
0101                    PL                             Plus/positive or zero                               N clear
0110                    VS                             Overflow                                                 V set
0111                    VC                             No overflow                                            V clear
1000                    HI                             Unsigned higher                                     C set and Z clear
1001                    LS                             Unsigned lower or same                        C clear or Z set
1010                    GE                             Signed greater than or equal                N set and V set, or N clear and V clear

(N == V)
1011 LT Signed less than N set and V clear, or N clear and V set

(N != V)
1100 GT Signed greater than Z clear, and either N set and V set, or N

clear and V clear (Z == 0,N == V)
1101 LE Signed less than or equal Z set, or N set and V clear, or N clear

                                                                                                                          and V set (Z == 1 or N != V)
1110                    AL                             Always (unconditional) -
1111                   -                             See Condition code 0b1111 -