Memory 裸机部件-数据未初始化
我编写了一些非常简单的代码，旨在处理裸机RaspberryPi。我的代码由gpio.s（具有打开和关闭LED的功能“flash”）和main.s组成，如下所示Memory 裸机部件-数据未初始化,memory,assembly,arm,raspberry-pi,Memory,Assembly,Arm,Raspberry Pi,我编写了一些非常简单的代码，旨在处理裸机RaspberryPi。我的代码由gpio.s（具有打开和关闭LED的功能“flash”）和main.s组成，如下所示 .section .init .globl _start _start: mov sp, $0x8000 b main .section .text .globl main main: ldr r5, =variable ldr r4, [r5] cmp r4
.section .init
.globl _start
_start:
mov sp, $0x8000
b main
.section .text
.globl main
main:
ldr r5, =variable
ldr r4, [r5]
cmp r4, $100
bleq flash
loop:
b loop
.section .data
.align 4
.globl variable
variable:
.word 100
./build/output.elf: file format elf32-littlearm
Disassembly of section .init:
00000000 <_start>:
0: e3a0d902 mov sp, #32768 ; 0x8000
4: ea00205c b 817c <main>
Disassembly of section .text:
00008000 <getGpioAddr>:
8000: e59f0170 ldr r0, [pc, #368] ; 8178 <flash2+0x14>
8004: e1a0f00e mov pc, lr
00008008 <setGpioFunct>:
8008: e3500035 cmp r0, #53 ; 0x35
800c: 93510007 cmpls r1, #7 ; 0x7
8010: 83a00001 movhi r0, #1 ; 0x1
8014: 81a0f00e movhi pc, lr
8018: e92d0030 push {r4, r5}
801c: e1a02001 mov r2, r1
8020: e1a01000 mov r1, r0
8024: e92d4000 push {lr}
8028: ebfffff4 bl 8000 <getGpioAddr>
802c: e8bd4000 pop {lr}
8030: e3a04000 mov r4, #0 ; 0x0
00008034 <subTen>:
8034: e351000a cmp r1, #10 ; 0xa
8038: 2241100a subcs r1, r1, #10 ; 0xa
803c: 22844001 addcs r4, r4, #1 ; 0x1
8040: 2afffffb bcs 8034 <subTen>
8044: e3a05004 mov r5, #4 ; 0x4
8048: e0030594 mul r3, r4, r5
804c: e0800003 add r0, r0, r3
8050: e3a05003 mov r5, #3 ; 0x3
8054: e0030591 mul r3, r1, r5
8058: e1a02312 lsl r2, r2, r3
805c: e3e0430e mvn r4, #939524096 ; 0x38000000
8060: e3a05009 mov r5, #9 ; 0x9
8064: e0451001 sub r1, r5, r1
8068: e3a05003 mov r5, #3 ; 0x3
806c: e0030591 mul r3, r1, r5
8070: e1a04374 ror r4, r4, r3
8074: e5905000 ldr r5, [r0]
8078: e0055004 and r5, r5, r4
807c: e1855002 orr r5, r5, r2
8080: e5805000 str r5, [r0]
8084: e8bd0030 pop {r4, r5}
8088: e3a00000 mov r0, #0 ; 0x0
808c: e1a0f00e mov pc, lr
00008090 <setPin>:
8090: e3500035 cmp r0, #53 ; 0x35
8094: 83a00001 movhi r0, #1 ; 0x1
8098: 81a0f00e movhi pc, lr
809c: e92d0020 push {r5}
80a0: e3500020 cmp r0, #32 ; 0x20
80a4: 22401020 subcs r1, r0, #32 ; 0x20
80a8: 31a01000 movcc r1, r0
80ac: 23a02020 movcs r2, #32 ; 0x20
80b0: 33a0201c movcc r2, #28 ; 0x1c
80b4: e92d4000 push {lr}
80b8: ebffffd0 bl 8000 <getGpioAddr>
80bc: e8bd4000 pop {lr}
80c0: e3a05001 mov r5, #1 ; 0x1
80c4: e1a05115 lsl r5, r5, r1
80c8: e7805002 str r5, [r0, r2]
80cc: e3a00000 mov r0, #0 ; 0x0
80d0: e8bd0020 pop {r5}
80d4: e1a0f00e mov pc, lr
000080d8 <clearPin>:
80d8: e3500035 cmp r0, #53 ; 0x35
80dc: 83a00001 movhi r0, #1 ; 0x1
80e0: 81a0f00e movhi pc, lr
80e4: e92d0020 push {r5}
80e8: e3500020 cmp r0, #32 ; 0x20
80ec: 22401020 subcs r1, r0, #32 ; 0x20
80f0: 31a01000 movcc r1, r0
80f4: 23a0202c movcs r2, #44 ; 0x2c
80f8: 33a02028 movcc r2, #40 ; 0x28
80fc: e92d4000 push {lr}
8100: ebffffbe bl 8000 <getGpioAddr>
8104: e8bd4000 pop {lr}
8108: e3a05001 mov r5, #1 ; 0x1
810c: e1a05115 lsl r5, r5, r1
8110: e7805002 str r5, [r0, r2]
8114: e3a00000 mov r0, #0 ; 0x0
8118: e8bd0020 pop {r5}
811c: e1a0f00e mov pc, lr
00008120 <flash>:
8120: e92d4013 push {r0, r1, r4, lr}
8124: e3a00010 mov r0, #16 ; 0x10
8128: e3a01001 mov r1, #1 ; 0x1
812c: ebffffb5 bl 8008 <setGpioFunct>
8130: e3a00010 mov r0, #16 ; 0x10
8134: ebffffe7 bl 80d8 <clearPin>
8138: eb000004 bl 8150 <wait>
813c: e3a00010 mov r0, #16 ; 0x10
8140: ebffffd2 bl 8090 <setPin>
8144: eb000001 bl 8150 <wait>
8148: e8bd4013 pop {r0, r1, r4, lr}
814c: e1a0f00e mov pc, lr
00008150 <wait>:
8150: e3a0583f mov r5, #4128768 ; 0x3f0000
00008154 <loop>:
8154: e2455001 sub r5, r5, #1 ; 0x1
8158: e3550000 cmp r5, #0 ; 0x0
815c: 1afffffc bne 8154 <loop>
8160: e1a0f00e mov pc, lr
00008164 <flash2>:
8164: e92d4000 push {lr}
8168: ebffffec bl 8120 <flash>
816c: ebffffeb bl 8120 <flash>
8170: e8bd4000 pop {lr}
8174: e1a0f00e mov pc, lr
8178: 20200000 .word 0x20200000
0000817c <main>:
817c: e59f500c ldr r5, [pc, #12] ; 8190 <loop+0x4>
8180: e5954000 ldr r4, [r5]
8184: e3540064 cmp r4, #100 ; 0x64
8188: 0bffffe4 bleq 8120 <flash>
0000818c <loop>:
818c: eafffffe b 818c <loop>
8190: 00008194 .word 0x00008194
Disassembly of section .data:
00008194 <variable>:
8194: 00000064 .word 0x00000064
/build/output.elf：文件格式elf32 littlearm
分解.init节：
00000000 :
0:e3a0d902 mov sp#32768；0x8000
4:ea00205c b 817c
第节的分解。正文：
00008000 :
8000:e59f0170 ldr r0，[pc，#368]；8178
8004:e1a0f00e mov pc，lr
00008008 :
8008:e3500035 cmp r0，#53；0x35
800c:93510007 cmpls r1，#7；0x7
8010:83a00001 movhi r0，#1；0x1
8014:81a0f00e movhi pc，lr
8018:e92d0030推送{r4，r5}
801c:e1a02001 mov r2，r1
8020:e1a01000 mov r1，r0
8024:e92d4000推送{lr}
8028:EBFFF4 bl 8000
802c:e8bd4000 pop{lr}
8030:e3a04000 mov r4，#0；0x0
00008034 :
8034:e351000a cmp r1，#10；0xa
8038:2241100a分包r1，r1，#10；0xa
803c:22844001 addcs r4，r4，#1；0x1
8040:2AFFFFB bcs 8034
8044:e3a05004 mov r5，#4；0x4
8048:e0030594 mul r3、r4、r5
804c:e0800003添加r0、r0、r3
8050:e3a05003 mov r5，#3；0x3
8054:e0030591 mul r3、r1、r5
8058:e1a02312 lsl r2、r2、r3
805c:e3e0430e mvn r4，#939524096；0x38000000
8060:e3a05009 mov r5，#9；0x9
8064:e0451001分接头r1、r5、r1
8068:e3a05003 mov r5，#3；0x3
806c:e0030591 mul r3、r1、r5
8070:e1a04374 ror r4、r4、r3
8074:e5905000 ldr r5[r0]
8078:e0055004和r5、r5、r4
807c:e1855002或r5、r5、r2
8080:e5805000 str r5[r0]
8084:E8BD030 pop{r4，r5}
8088:e3a00000 mov r0，#0；0x0
808c:e1a0f00e mov pc，lr
00008090 :
8090:e3500035 cmp r0，#53；0x35
8094:83a00001 movhi r0，#1；0x1
8098:81a0f00e movhi pc，lr
809c:e92d0020推送{r5}
80a0:e3500020 cmp r0，#32；0x20
80a4:22401020分包r1、r0、#32；0x20
80a8:31a01000 movcc r1，r0
80ac:23a02020 movcs r2，#32；0x20
80b0:33a0201c movcc r2，#28；0x1c
80b4:e92d4000推送{lr}
80b8:ebffffd0 bl 8000
80bc:e8bd4000 pop{lr}
80c0:e3a05001 mov r5，#1；0x1
80c4:e1a05115 lsl r5、r5、r1
80c8:e7805002 str r5[r0，r2]
80cc:e3a00000 mov r0，#0；0x0
80d0:E8BD020 pop{r5}
80d4:e1a0f00e mov pc，lr
000080d8：
80d8:e3500035 cmp r0，#53；0x35
80dc:83a00001 movhi r0，#1；0x1
80e0:81a0f00e movhi pc，lr
80e4:e92d0020推送{r5}
80e8:e3500020 cmp r0，#32；0x20
80ec:22401020分包r1、r0、#32；0x20
80f0:31a01000 movcc r1，r0
80f4:23a0202c movcs r2，#44；0x2c
80f8:33a02028 movcc r2，#40；0x28
80fc:e92d4000推送{lr}
8100:ebffffbe bl 8000
8104:e8bd4000 pop{lr}
8108:e3a05001 mov r5，#1；0x1
810c:e1a05115 lsl r5、r5、r1
8110:e7805002 str r5[r0，r2]
8114:e3a00000 mov r0，#0；0x0
8118:E8BD020 pop{r5}
811c:e1a0f00e mov pc，lr
00008120 :
8120:e92d4013推送{r0，r1，r4，lr}
8124:e3a00010 mov r0，#16；0x10
8128:e3a01001 mov r1，#1；0x1
812c:EBFFB5 bl 8008
8130:e3a00010 mov r0，#16；0x10
8134:ebffffe7 bl 80d8
8138:eb000004 bl 8150
813c:e3a00010 mov r0，#16；0x10
8140:ebffffd2 bl 8090
8144:eb000001 bl 8150
8148:e8bd4013 pop{r0，r1，r4，lr}
814c:e1a0f00e mov pc，lr
00008150 :
8150:e3a0583f mov r5，#4128768；0x3f0000
00008154 :
8154:e2455001子r5，r5，#1；0x1
8158:e3550000 cmp r5，#0；0x0
815c:1afffffc bne 8154
8160:e1a0f00e mov pc，lr
00008164 :
8164:e92d4000推送{lr}
8168:ebffffec bl 8120
816c:EBFFFFB bl 8120
8170:e8bd4000 pop{lr}
8174:e1a0f00e mov pc，lr
8178:20200000。单词0x20200000
0000817c：
817c:e59f500c ldr r5，[pc，#12]；8190
8180:e5954000 ldr r4[r5]
8184:e3540064 cmp r4，#100；0x64
8188:0bffffe4 bleq 8120
0000818c：
818c:eafffffe b 818c
8190:00008194.字0x00008194
分解截面。数据：
00008194 :
8194:00000064。字0x00000064
0000817c:
817c:e59f500c ldr r5，[pc，#12]；8190
8180:e3a01064 mov r1，#100；0x64
8184:e3540064 cmp r4，#100；0x64
8188:0bffffe4 bleq 8120
0000818c：
818c:eafffffe b 818c
8190:000081a0.字0x000081a0
分解截面。数据：
000081a0：
81a0:00000064。字0x00000064
...
./build/output.elf: file format elf32-littlearm
Disassembly of section .init:
00000000 <_start>:
0: e3a0d902 mov sp, #32768 ; 0x8000
4: ea00205c b 817c <main>
Disassembly of section .text:
00008000 <getGpioAddr>:
8000: e59f0170 ldr r0, [pc, #368] ; 8178 <flash2+0x14>
8004: e1a0f00e mov pc, lr
00008008 <setGpioFunct>:
8008: e3500035 cmp r0, #53 ; 0x35
800c: 93510007 cmpls r1, #7 ; 0x7
8010: 83a00001 movhi r0, #1 ; 0x1
8014: 81a0f00e movhi pc, lr
8018: e92d0030 push {r4, r5}
801c: e1a02001 mov r2, r1
8020: e1a01000 mov r1, r0
8024: e92d4000 push {lr}
8028: ebfffff4 bl 8000 <getGpioAddr>
802c: e8bd4000 pop {lr}
8030: e3a04000 mov r4, #0 ; 0x0
00008034 <subTen>:
8034: e351000a cmp r1, #10 ; 0xa
8038: 2241100a subcs r1, r1, #10 ; 0xa
803c: 22844001 addcs r4, r4, #1 ; 0x1
8040: 2afffffb bcs 8034 <subTen>
8044: e3a05004 mov r5, #4 ; 0x4
8048: e0030594 mul r3, r4, r5
804c: e0800003 add r0, r0, r3
8050: e3a05003 mov r5, #3 ; 0x3
8054: e0030591 mul r3, r1, r5
8058: e1a02312 lsl r2, r2, r3
805c: e3e0430e mvn r4, #939524096 ; 0x38000000
8060: e3a05009 mov r5, #9 ; 0x9
8064: e0451001 sub r1, r5, r1
8068: e3a05003 mov r5, #3 ; 0x3
806c: e0030591 mul r3, r1, r5
8070: e1a04374 ror r4, r4, r3
8074: e5905000 ldr r5, [r0]
8078: e0055004 and r5, r5, r4
807c: e1855002 orr r5, r5, r2
8080: e5805000 str r5, [r0]
8084: e8bd0030 pop {r4, r5}
8088: e3a00000 mov r0, #0 ; 0x0
808c: e1a0f00e mov pc, lr
00008090 <setPin>:
8090: e3500035 cmp r0, #53 ; 0x35
8094: 83a00001 movhi r0, #1 ; 0x1
8098: 81a0f00e movhi pc, lr
809c: e92d0020 push {r5}
80a0: e3500020 cmp r0, #32 ; 0x20
80a4: 22401020 subcs r1, r0, #32 ; 0x20
80a8: 31a01000 movcc r1, r0
80ac: 23a02020 movcs r2, #32 ; 0x20
80b0: 33a0201c movcc r2, #28 ; 0x1c
80b4: e92d4000 push {lr}
80b8: ebffffd0 bl 8000 <getGpioAddr>
80bc: e8bd4000 pop {lr}
80c0: e3a05001 mov r5, #1 ; 0x1
80c4: e1a05115 lsl r5, r5, r1
80c8: e7805002 str r5, [r0, r2]
80cc: e3a00000 mov r0, #0 ; 0x0
80d0: e8bd0020 pop {r5}
80d4: e1a0f00e mov pc, lr
000080d8 <clearPin>:
80d8: e3500035 cmp r0, #53 ; 0x35
80dc: 83a00001 movhi r0, #1 ; 0x1
80e0: 81a0f00e movhi pc, lr
80e4: e92d0020 push {r5}
80e8: e3500020 cmp r0, #32 ; 0x20
80ec: 22401020 subcs r1, r0, #32 ; 0x20
80f0: 31a01000 movcc r1, r0
80f4: 23a0202c movcs r2, #44 ; 0x2c
80f8: 33a02028 movcc r2, #40 ; 0x28
80fc: e92d4000 push {lr}
8100: ebffffbe bl 8000 <getGpioAddr>
8104: e8bd4000 pop {lr}
8108: e3a05001 mov r5, #1 ; 0x1
810c: e1a05115 lsl r5, r5, r1
8110: e7805002 str r5, [r0, r2]
8114: e3a00000 mov r0, #0 ; 0x0
8118: e8bd0020 pop {r5}
811c: e1a0f00e mov pc, lr
00008120 <flash>:
8120: e92d4013 push {r0, r1, r4, lr}
8124: e3a00010 mov r0, #16 ; 0x10
8128: e3a01001 mov r1, #1 ; 0x1
812c: ebffffb5 bl 8008 <setGpioFunct>
8130: e3a00010 mov r0, #16 ; 0x10
8134: ebffffe7 bl 80d8 <clearPin>
8138: eb000004 bl 8150 <wait>
813c: e3a00010 mov r0, #16 ; 0x10
8140: ebffffd2 bl 8090 <setPin>
8144: eb000001 bl 8150 <wait>
8148: e8bd4013 pop {r0, r1, r4, lr}
814c: e1a0f00e mov pc, lr
00008150 <wait>:
8150: e3a0583f mov r5, #4128768 ; 0x3f0000
00008154 <loop>:
8154: e2455001 sub r5, r5, #1 ; 0x1
8158: e3550000 cmp r5, #0 ; 0x0
815c: 1afffffc bne 8154 <loop>
8160: e1a0f00e mov pc, lr
00008164 <flash2>:
8164: e92d4000 push {lr}
8168: ebffffec bl 8120 <flash>
816c: ebffffeb bl 8120 <flash>
8170: e8bd4000 pop {lr}
8174: e1a0f00e mov pc, lr
8178: 20200000 .word 0x20200000
0000817c <main>:
817c: e59f500c ldr r5, [pc, #12] ; 8190 <loop+0x4>
8180: e5954000 ldr r4, [r5]
8184: e3540064 cmp r4, #100 ; 0x64
8188: 0bffffe4 bleq 8120 <flash>
0000818c <loop>:
818c: eafffffe b 818c <loop>
8190: 00008194 .word 0x00008194
Disassembly of section .data:
00008194 <variable>:
8194: 00000064 .word 0x00000064
0000817c <main>:
817c: e59f500c ldr r5, [pc, #12] ; 8190 <loop+0x4>
8180: e3a01064 mov r1, #100 ; 0x64
8184: e3540064 cmp r4, #100 ; 0x64
8188: 0bffffe4 bleq 8120 <flash>
0000818c <loop>:
818c: eafffffe b 818c <loop>
8190: 000081a0 .word 0x000081a0
Disassembly of section .data:
000081a0 <variable>:
81a0: 00000064 .word 0x00000064
...
SECTIONS {
/*
* First and formost we need the .init section, containing the IVT.
*/
.init 0x0000 : {
*(.init)
}
/*
* We allow room for the ATAGs and the stack and then start our code at
* 0x8000.
*/
.text 0x8000 : {
*(.text)
}
/*
* Next we put the data.
*/
.data : {
*(.data)
}
/*
* Finally comes everything else. A fun trick here is to put all other
* sections into this section, which will be discarded by default.
*/
/DISCARD/ : {
*(*)
}
}
SECTIONS {
/*
* First and formost we need the .init section, containing the IVT.
*/
.init 0x8000 : {
*(.init)
}
.text : {
*(.text)
}
/*
* Next we put the data.
*/
.data : {
*(.data)
}
/*
* Finally comes everything else. A fun trick here is to put all other
* sections into this section, which will be discarded by default.
*/
/DISCARD/ : {
*(*)
}
}