MMU粗页代码

来源：互联网发布：淘宝主图尺寸 2017 编辑：程序博客网时间：2024/04/28 01:38

最近几天稍微打算再把MMU的一些粗页代码写下，这个代码和上一次的段页映射都一样，都是一一映射，其他的映射关系也一样，区别就是这边用了二级映射关系，页面全部换成粗页，1024*4096个large page我也是醉了，不过我打算之后再弄得更细点，而且结构层次这次也分得不好，整个汇编代码冗余度也很高，感觉自己用汇编写个通用的函数还是太累了，不想把时间花在一个实验例程上。

0x0000 0000 ->0x0000 0000
.......
0xf000 0000 -> 0xf000 0000

0xb000 0000 ->GPIO口 0x5600 0000
0xc000 0000 ->led程序入口 0x3200 0000

////////////////////////////////////////////////
.equ MMU_COARSE_DOMAIN,( (0) <<5 )

.equ MMU_SPECIAL, ( (1) <<4 )

.equ MMU_COARSE_DESC, 0x01

.equ MMU_COARSE_NORMAL, ( MMU_COARSE_DOMAIN | MMU_SPECIAL | MMU_COARSE_DESC )

.equ COARSE_AP_0, ( (3) <<4 )

.equ COARSE_AP_1, ( (3) <<6 )

.equ COARSE_AP_2, ( (3) <<8 )

.equ COARSE_AP_3, ( (3) <<10 )

.equ COARSE_FULL_ACESS, ( COARSE_AP_0 | COARSE_AP_1 | COARSE_AP_2 | COARSE_AP_3 )

.equ COARSE_CACHE, ( (1) << 3)

.equ COARSE_BUFFER, ( (1) << 2)

.equ COARSE_DESC, (0x01)

.equ COARSE_NORMAL, ( COARSE_FULL_ACESS | COARSE_DESC)

.equ COARSE_WB, ( COARSE_NORMAL | COARSE_CACHE | COARSE_BUFFER)

.equ MMU_BASE_ADDR, 0x30200000

.equ COARSE_BASE_ADDR, 0x30200000+4096*4

.equ PA,0X00

.equ VA,0X00

.equ ENDPA,0xf0000000

start:

stmfd sp!,{r0-r12,lr}

begin:

mov r3,#0

ldr r5,=ENDPA

lsr r4,r5,#20

ldr r11,=MMU_BASE_ADDR

ldr r12,=COARSE_BASE_ADDR

forLoopI:

cmp r4,r3

bcc NEXT

mov r1,#4

mul r2,r1,r3

add r2,r2,r11

lsl r1,r3,#10

ldr r9,=MMU_COARSE_NORMAL

add r1,r1,r12

bic r1,r1,#0x0300

bic r1,r1,#0x00f0

bic r1,r1,#0x000f

orr r10,r1,r9

str r10,[r2]

J_begin:

mov r5,#0

mov r7,#16

mov r8,#0

forLoopJ:

cmp r7,r5

bcc END_R8

mov r6,#4

mul r9,r6,r5

add r2,r1,r9

mov r6,#64

mul r9,r6,r8

add r2,r2,r9

lsl r6,r3,#20

mov r10,r6

lsl r6,r8,#16

add r10,r10,r6

mov r6,r10

ldr r10,=COARSE_NORMAL

orr r10,r6,r10

str r10,[r2]

add r5,r5,#1

b forLoopJ

END_R8:

cmp r7,r8

bcc END_I

mov r5,#0

add r8,r8,#1

b forLoopJ

END_I:

add r3,r3,#1

b forLoopI

.equ LED_ADR,0xb0000000

.equ LED_P_ADDR,0x56000000

.equ LED_BIN,0xc0000000

.equ LED_P_BIN,0x32000000

ldr r1,=LED_ADR

ldr r2,=LED_P_ADDR

ldr r3,=LED_BIN

ldr r4,=LED_P_BIN

lsr r5,r1,#20

mov r6,#4

mul r7,r6,r5

add r6,r7,r11

ldr r7,[r6]

bic r7,r7,#0x300

bic r7,r7,#0x0f0

bic r7,r7,#0x00f

lsl r5,r1,#22

lsr r5,r5,#24

lsl r5,r5,#2

orr r6,r7,r5

ldr r7,=LED_P_ADDR

bic r7,r7,#0xf000

bic r7,r7,#0x0f00

bic r7,r7,#0x00f0

bic r7,r7,#0x000f

ldr r8,=COARSE_NORMAL

orr r9,r7,r8

str r9,[r6]

BIN:

lsr r5,r3,#20

mov r6,#4

mul r7,r6,r5

add r6,r7,r11

ldr r7,[r6]

bic r7,r7,#0x300

bic r7,r7,#0x0f0

bic r7,r7,#0x00f

lsl r5,r3,#22

lsr r5,r5,#24

lsl r5,r5,#2

orr r6,r7,r5

ldr r7,=LED_P_BIN

bic r7,r7,#0xf000

bic r7,r7,#0x0f00

bic r7,r7,#0x00f0

bic r7,r7,#0x000f

ldr r8,=COARSE_NORMAL

orr r9,r7,r8

str r9,[r6]

START_MMU:

mov r0, #0

mcr p15, 0, r0, c7, c7, 0

mcr p15, 0, r0, c7, c10, 4

mcr p15, 0, r0, c8, c7, 0

ldr r4,=MMU_BASE_ADDR

mcr p15, 0, r4, c2, c0, 0

mvn r0, #0

mcr p15, 0, r0, c3, c0, 0

mrc p15, 0, r0, c1, c0, 0

bic r0, r0, #0x3000

bic r0, r0, #0x0300

bic r0, r0, #0x0087

orr r0, r0, #0x0002

orr r0, r0, #0x0004

orr r0, r0, #0x1000

orr r0, r0, #0x0001

mcr p15, 0, r0, c1, c0, 0

return:

ldmfd sp!,{r0-r12,pc}

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