所以在二进制整型数字的除法世界中，只需要减法和移位操作就能够满足除法运算的需求。最后我才发现，二进制的除法原本就是这么简单，比十进制的除法还要简单。
本文完，以下为参考资料。
arm的指令集查文档：
~valvano/Volume1/QuickReferenceCard.pdf
https://iitd-plos.github.io/col718/ref/arm-instructionset.pdf
div无符号整形的除法汇编如下：
00010490 <__udivsi3>:
10490:
1e4a
subs r2, r1, #1
10492:
bf08
it
eq
10494:
4770
bxeq lr
10496:
f0c0 8124
bcc.w 106e2 <__udivsi3+0x252>
1049a:
4288
cmp
r0, r1
1049c:
f240 8116
bls.w 106cc <__udivsi3+0x23c>
104a0:
4211
tst
r1, r2
104a2:
f000 8117
beq.w 106d4 <__udivsi3+0x244>
104a6:
fab0 f380
clz
r3, r0
104aa:
fab1 f281
clz
r2, r1
104ae:
eba2 0303
sub.w r3, r2, r3
104b2:
f1c3 031f
rsb
r3, r3, #31
104b6:
a204
add
r2, pc, #16
; (adr r2, 104c8 <__udivsi3+0x38>)
104b8:
eb02 1303
add.w r3, r2, r3, lsl #4
104bc:
f04f 0200
mov.w r2, #0
104c0:
469f
mov
pc, r3
104c2:
bf00
nop
104c4:
f3af 8000
nop.w
104c8:
ebb0 7fc1
cmp.w r0, r1, lsl #31
104cc:
bf00
nop
104ce:
eb42 0202
adc.w r2, r2, r2
104d2:
bf28
it
cs
104d4:
eba0 70c1
subcs.w r0, r0, r1, lsl #31
104d8:
ebb0 7f81
cmp.w r0, r1, lsl #30
104dc:
bf00
nop
104de:
eb42 0202
adc.w r2, r2, r2
104e2:
bf28
it
cs
104e4:
eba0 7081
subcs.w r0, r0, r1, lsl #30
104e8:
ebb0 7f41
cmp.w r0, r1, lsl #29
104ec:
bf00
nop
104ee:
eb42 0202
adc.w r2, r2, r2
104f2:
bf28
it
cs
104f4:
eba0 7041
subcs.w r0, r0, r1, lsl #29
104f8:
ebb0 7f01
cmp.w r0, r1, lsl #28
104fc:
bf00
nop
104fe:
eb42 0202
adc.w r2, r2, r2
10502:
bf28
it
cs
10504:
eba0 7001
subcs.w r0, r0, r1, lsl #28
10508:
ebb0 6fc1
cmp.w r0, r1, lsl #27
1050c:
bf00
nop
1050e:
eb42 0202
adc.w r2, r2, r2
10512:
bf28
it
cs
10514:
eba0 60c1
subcs.w r0, r0, r1, lsl #27
10518:
ebb0 6f81
cmp.w r0, r1, lsl #26
1051c:
bf00
nop
1051e:
eb42 0202
adc.w r2, r2, r2
10522:
bf28
it
cs
10524:
eba0 6081
subcs.w r0, r0, r1, lsl #26
10528:
ebb0 6f41
cmp.w r0, r1, lsl #25
1052c:
bf00
nop
1052e:
eb42 0202
adc.w r2, r2, r2
10532:
bf28
it
cs
10534:
eba0 6041
subcs.w r0, r0, r1, lsl #25
10538:
ebb0 6f01
cmp.w r0, r1, lsl #24
1053c:
bf00
nop
1053e:
eb42 0202
adc.w r2, r2, r2
10542:
bf28
it
cs
10544:
eba0 6001
subcs.w r0, r0, r1, lsl #24
10548:
ebb0 5fc1
cmp.w r0, r1, lsl #23
1054c:
bf00
nop
1054e:
eb42 0202
adc.w r2, r2, r2
10552:
bf28
it
cs
10554:
eba0 50c1
subcs.w r0, r0, r1, lsl #23
10558:
ebb0 5f81
cmp.w r0, r1, lsl #22
1055c:
bf00
nop
1055e:
eb42 0202
adc.w r2, r2, r2
10562:
bf28
it
cs
10564:
eba0 5081
subcs.w r0, r0, r1, lsl #22
10568:
ebb0 5f41
cmp.w r0, r1, lsl #21
1056c:
bf00
nop
1056e:
eb42 0202
adc.w r2, r2, r2
10572:
bf28
it
cs
10574:
eba0 5041
subcs.w r0, r0, r1, lsl #21
10578:
ebb0 5f01
cmp.w r0, r1, lsl #20
1057c:
bf00
nop
1057e:
eb42 0202
adc.w r2, r2, r2
10582:
bf28
it
cs
10584:
eba0 5001
subcs.w r0, r0, r1, lsl #20
10588:
ebb0 4fc1
cmp.w r0, r1, lsl #19
1058c:
bf00
nop
1058e:
eb42 0202
adc.w r2, r2, r2
10592:
bf28
it
cs
10594:
eba0 40c1
subcs.w r0, r0, r1, lsl #19
10598:
ebb0 4f81
cmp.w r0, r1, lsl #18
1059c:
bf00
nop
1059e:
eb42 0202
adc.w r2, r2, r2
105a2:
bf28
it
cs
105a4:
eba0 4081
subcs.w r0, r0, r1, lsl #18
105a8:
ebb0 4f41
cmp.w r0, r1, lsl #17
105ac:
bf00
nop
105ae:
eb42 0202
adc.w r2, r2, r2
105b2:
bf28
it
cs
105b4:
eba0 4041
subcs.w r0, r0, r1, lsl #17
105b8:
ebb0 4f01
cmp.w r0, r1, lsl #16
105bc:
bf00
nop
105be:
eb42 0202
adc.w r2, r2, r2
105c2:
bf28
it
cs
105c4:
eba0 4001
subcs.w r0, r0, r1, lsl #16
105c8:
ebb0 3fc1
cmp.w r0, r1, lsl #15
105cc:
bf00
nop
105ce:
eb42 0202
adc.w r2, r2, r2
105d2:
bf28
it
cs
105d4:
eba0 30c1
subcs.w r0, r0, r1, lsl #15
105d8:
ebb0 3f81
cmp.w r0, r1, lsl #14
105dc:
bf00
nop
105de:
eb42 0202
adc.w r2, r2, r2
105e2:
bf28
it
cs
105e4:
eba0 3081
subcs.w r0, r0, r1, lsl #14
105e8:
ebb0 3f41
cmp.w r0, r1, lsl #13
105ec:
bf00
nop
105ee:
eb42 0202
adc.w r2, r2, r2
105f2:
bf28
it
cs
105f4:
eba0 3041
subcs.w r0, r0, r1, lsl #13
105f8:
ebb0 3f01
cmp.w r0, r1, lsl #12
105fc:
bf00
nop
105fe:
eb42 0202
adc.w r2, r2, r2
10602:
bf28
it
cs
10604:
eba0 3001
subcs.w r0, r0, r1, lsl #12
10608:
ebb0 2fc1
cmp.w r0, r1, lsl #11
1060c:
bf00
nop
1060e:
eb42 0202
adc.w r2, r2, r2
10612:
bf28
it
cs
10614:
eba0 20c1
subcs.w r0, r0, r1, lsl #11
10618:
ebb0 2f81
cmp.w r0, r1, lsl #10
1061c:
bf00
nop
1061e:
eb42 0202
adc.w r2, r2, r2
10622:
bf28
it
cs
10624:
eba0 2081
subcs.w r0, r0, r1, lsl #10
10628:
ebb0 2f41
cmp.w r0, r1, lsl #9
1062c:
bf00
nop
1062e:
eb42 0202
adc.w r2, r2, r2
10632:
bf28
it
cs
10634:
eba0 2041
subcs.w r0, r0, r1, lsl #9
10638:
ebb0 2f01
cmp.w r0, r1, lsl #8
1063c:
bf00
nop
1063e:
eb42 0202
adc.w r2, r2, r2
10642:
bf28
it
cs
10644:
eba0 2001
subcs.w r0, r0, r1, lsl #8
10648:
ebb0 1fc1
cmp.w r0, r1, lsl #7
1064c:
bf00
nop
1064e:
eb42 0202
adc.w r2, r2, r2
10652:
bf28
it
cs
10654:
eba0 10c1
subcs.w r0, r0, r1, lsl #7
10658:
ebb0 1f81
cmp.w r0, r1, lsl #6
1065c:
bf00
nop
1065e:
eb42 0202
adc.w r2, r2, r2
10662:
bf28
it
cs
10664:
eba0 1081
subcs.w r0, r0, r1, lsl #6
10668:
ebb0 1f41
cmp.w r0, r1, lsl #5
1066c:
bf00
nop
1066e:
eb42 0202
adc.w r2, r2, r2
10672:
bf28
it
cs
10674:
eba0 1041
subcs.w r0, r0, r1, lsl #5
10678:
ebb0 1f01
cmp.w r0, r1, lsl #4
1067c:
bf00
nop
1067e:
eb42 0202
adc.w r2, r2, r2
10682:
bf28
it
cs
10684:
eba0 1001
subcs.w r0, r0, r1, lsl #4
10688:
ebb0 0fc1
cmp.w r0, r1, lsl #3
1068c:
bf00
nop
1068e:
eb42 0202
adc.w r2, r2, r2
10692:
bf28
it
cs
10694:
eba0 00c1
subcs.w r0, r0, r1, lsl #3
10698:
ebb0 0f81
cmp.w r0, r1, lsl #2
1069c:
bf00
nop
1069e:
eb42 0202
adc.w r2, r2, r2
106a2:
bf28
it
cs
106a4:
eba0 0081
subcs.w r0, r0, r1, lsl #2
106a8:
ebb0 0f41
cmp.w r0, r1, lsl #1
106ac:
bf00
nop
106ae:
eb42 0202
adc.w r2, r2, r2
106b2:
bf28
it
cs
106b4:
eba0 0041
subcs.w r0, r0, r1, lsl #1
106b8:
ebb0 0f01
cmp.w r0, r1
106bc:
bf00
nop
106be:
eb42 0202
adc.w r2, r2, r2
106c2:
bf28
it
cs
106c4:
eba0 0001
subcs.w r0, r0, r1
106c8:
4610
mov
r0, r2
106ca:
4770
bx
lr
106cc:
bf0c
ite
eq
106ce:
2001
moveq r0, #1
106d0:
2000
movne r0, #0
106d2:
4770
bx
lr
106d4:
fab1 f281
clz
r2, r1
106d8:
f1c2 021f
rsb
r2, r2, #31
106dc:
fa20 f002
lsr.w r0, r0, r2
106e0:
4770
bx
lr
106e2:
b108
cbz
r0, 106e8 <__udivsi3+0x258>
106e4:
f04f 30ff
mov.w r0, #4294967295 ; 0xffffffff
106e8:
f000 b966
b.w
109b8 <__aeabi_idiv0>
