在上一篇进行了汇编语言的编写后，这一节采用C语言来编写，毕竟C语言才是我们使用最多的语言。
本节要点：
1）用C语言方式点亮LED灯；
2）分析反汇编代码；了解函数调用栈，深入的分析代码；
3）编写C语言的库函数版本，方便以后开发；
首先贴出一段代码：
start.s
.text
.global _start
_start:
/* 设置内存: sp 栈 */
ldr sp, =4096 /* nand启动 */
// ldr sp, =0x40000000+4096 /* nor启动 */
/* 调用main */
bl main
halt:
b halt
LED.c：
int main()
{
unsigned int *pGPFCON = (unsigned int *)0x56000050;
unsigned int *pGPFDAT = (unsigned int *)0x56000054;
/* 配置GPF4为输出引脚 */
*pGPFCON = 0x100;
/* 设置GPF4输出0 */
*pGPFDAT = 0;
return 0;
}
在传统的IDE开发当中，我们只用从main函数开始写代码就行了，但是IDE隐藏了太多技术细节。
我们在arm嵌入式linux开发过程中，都需要自己来，这对初学者是不友好，但是对深入学习却很有帮助。
首先，nand flash启动，使用片内4K sram。
我们都知道，函数调用和局部变量的存储需要使用到一种叫做栈的数据结构。
说明：s3c2440，采用默认的栈生长方式，这也是我们最常见的方式，高地址往低地址生长。
要调用main函数，我们需要开辟栈，这里使用片内4K内存作为栈。
看一下反汇编：
led.elf: file format elf32-littlearm
Disassembly of section .text:
<_start>:
0: e3a0da01 mov sp, #4096 ; 0x1000
4: eb000000 bl c <main>
<halt>:
8: eafffffe b 8 <halt>
0000000c <main>:
c: e1a0c00d mov ip, sp
10: e92dd800 stmdb sp!, {fp, ip, lr, pc}
14: e24cb004 sub fp, ip, #4 ; 0x4
18: e24dd008 sub sp, sp, #8 ; 0x8
1c: e3a03456 mov r3, #1442840576 ; 0x56000000
20: e2833050 add r3, r3, #80 ; 0x50
24: e50b3010 str r3, [fp, #-16]
28: e3a03456 mov r3, #1442840576 ; 0x56000000
2c: e2833054 add r3, r3, #84 ; 0x54
30: e50b3014 str r3, [fp, #-20]
34: e51b2010 ldr r2, [fp, #-16]
38: e3a03c01 mov r3, #256 ; 0x100
3c: e5823000 str r3, [r2]
40: e51b2014 ldr r2, [fp, #-20]
44: e3a03000 mov r3, #0 ; 0x0
48: e5823000 str r3, [r2]
4c: e3a03000 mov r3, #0 ; 0x0
50: e1a00003 mov r0, r3
54: e24bd00c sub sp, fp, #12 ; 0xc
58: e89da800 ldmia sp, {fp, sp, pc}
Disassembly of section .comment:
<.comment>:
0: 43434700 cmpmi r3, #0 ; 0x0
4: 4728203a undefined
8: 2029554e eorcs r5, r9, lr, asr #10
c: 2e342e33 mrccs 14, 1, r2, cr4, cr3, {1}
10: Address 0x10 is out of bounds.
说明：
<.comment>:在上面的反汇编当中，它不是汇编代码的一部分，是注解，给我们一些提示，便于我们阅读、理解的。在讲解这个汇编之前，我们需要先看一个arm寄存器的别名表。
现在开始分析，其中最重要的也是新出现的两个指令：
stmdb，ldmia
简单说明，db表示事先递减方式，ia表示事后递增方式。
详细介绍可以参见 arm嵌入式系统开发P58。
先对反汇编进行注解：
led.elf: file format elf32-littlearm
Disassembly of section .text:
<_start>:
0: e3a0da01 mov sp, #4096 ; 赋值4096给sp堆栈寄存器
4: eb000000 bl c <main> ;跳转到main函数，同时保存main函数返回地址到lr寄存器，返回地址为下一条指令的地址，这里lr应为8
<halt>:
8: eafffffe b 8 <halt>;死循环
0000000c <main>:
c: e1a0c00d mov ip, sp;备份sp寄存器的值到ip，ip是r12寄存器的别名
10: e92dd800 stmdb sp!, {fp, ip, lr, pc}
; 这条指令需要重点讲解，首先，fp，ip，lr，pc分别对应寄存器：r11，r12，r14，r15
; stm指令多寄存器操作的时候，后面的寄存器从编号高的先开始存储，把后面几个寄存器的值写入sp所对应的内存块中，（注意和但寄存器操作区分开来）后缀db表示 先减后存储
; sp后面加了一个感叹号!,表示sp最后的值等于最后被修改的值，不加感叹号就算操作使sp更改过，sp也等于最初的值
; 首先操作r15，即pc，sp先减，sp=sp-4，此时sp=4092,pc等于当前指令地址加8，即此时pc=0x10+8=0x18，相当于把0x18写入sram地址4092
; 同理操作r14，即lr，sp=sp-4，lr=8，相当于把0x8写入4088地址
; r12，ip是等于4096的，上面的move指令，r11，fp的值此时未定
14: e24cb004 sub fp, ip, #4 ; fp=ip-4=4092 18: e24dd008 sub sp, sp, #8 ; sp=sp-8=4072 1c: e3a03456 mov r3, #1442840576 ;#1442840576等于十六机制0x56000000，把这个数存放在r3中 20: e2833050 add r3, r3, #80 ;r3=r3+80=0x56000050 24: e50b3010 str r3, [fp, #-16];fp-16=4076，把0x56000050放入内存4076中 28: e3a03456 mov r3, #1442840576 ; 0x56000000 2c: e2833054 add r3, r3, #84 ; r3=0x56000054 30: e50b3014 str r3, [fp, #-20];fp=fp-20=4072,把0x56000054放入内存4072中 34: e51b2010 ldr r2, [fp, #-16];r2=[fp-16=4076]=0x56000050 38: e3a03c01 mov r3, #256; r3==256=0x100 3c: e5823000 str r3, [r2];把0x100存入[0x56000050] 40: e51b2014 ldr r2, [fp, #-20];r2=[fp-20=4072]=0x56000054 44: e3a03000 mov r3, #0 ; r3=0=0x0 48: e5823000 str r3, [r2];把0x0存入0x56000054内存中 4c: e3a03000 mov r3, #0 ; r3=0x0 50: e1a00003 mov r0, r3;r0=r3=0x0,这里编译器有点笨，可以直接r0给0的，这里对应return 0. 54: e24bd00c sub sp, fp, #12 ; sp=fp-12=4080
58: e89da800 ldmia sp, {fp, sp, pc}
;恢复保存的现场，ldmia，事后增加，从sp所对应内存块中取出数据存放到后面的寄存器，高编号的寄存器放在高地址，低编号的寄存器
;放在低地址，此时sp=4080,从低地址往高地址开始恢复，这也符合ia后缀
;先恢复fp，此时4080地址存放的值，注意是值不是地址，等于4092，恰好就是等于fp，即一顿操作之后，fp还是等于原来的fp
;再恢复sp，sp=sp+4=4084，内存4084对应的值是4096，即一顿操作之后，sp又等于4096了；
;最后恢复pc，sp=sp+4=4088，内存4088对应的值是8，即一段操作之后，pc=8了，pc等于8意味着什么？意味着函数从main函数返回了，将去执行那个死循环halt
为了更好的理解函数入栈，让我们深入理解C语言底层汇编，画出内存示意图：
你可能会说。0-4096不是4097了吗？这样问非常好，不放过任何有疑问的细节，但是，4096，可以是4096的开始，也可以是4095的结尾，这里表示的是4095的结尾，因为4096我们一来是要先减4的。上图的4096是没用使用到真正属于4096地址后扩4字节的，而是在刚好到达4096时，之前的内存。
到这里，终于完成了一大半，我们知道了函数入栈之后，似乎函数调用的参数传递，也要用到栈啊，那么我们继续挖掘汇编。这里又需要补充几点arm方面的知识。
现在编写汇编代码， 传递一个参数：
.text
.global _start
_start:
/* 设置内存: sp 栈 */
ldr sp, =4096 /* nand启动 */
// ldr sp, =0x40000000+4096 /* nor启动 */
mov r0, #4
bl led_on
ldr r0, =100000
bl delay
mov r0, #5
bl led_on
halt:
b halt
void delay(volatile int d)
{
while (d--);
}
int led_on(int which)
{
unsigned int *pGPFCON = (unsigned int *)0x56000050;
unsigned int *pGPFDAT = (unsigned int *)0x56000054;
if (which == 4)
{
/* 配置GPF4为输出引脚 */
*pGPFCON = 0x100;
}
else if (which == 5)
{
/* 配置GPF5为输出引脚 */
*pGPFCON = 0x400;
}
/* 设置GPF4/5输出0 */
*pGPFDAT = 0;
return 0;
}
上面汇编中，只对应一个参数，所以只用r0就可以达到函数参数传递的效果，汇编比较简单就不赘述了。
这个例子是为了让我们了解汇编通过寄存器传递函数参数，前提是必须先设置sp寄存器。
甚至不必编写main函数，当然不建议这样做，这样示例是为让你明白一点，main函数也是因为启动代码去调用了它，我们通过改写启动代码，可以没有main函数。
终于到了我们最熟悉的阶段了，编写C语言应用程序，一般来说，复杂的和可复用性更高的代码我们肯定是用C语言编写，全用汇编编写代码真是很慢而且麻烦，更不用说机器码编程了，但是了解它们对我们深入学习又十分有用，这或许就是arm对初学者不友好的原因吧，因为现在为止我们还没有大型项目需要编写复杂的Makefile，后面还有很多技能需要get，这也是在买了板子大半年了才真的开始上手的原因，需要花时间补习其他知识。
言归正传，如上面的C语言程序，虽然完成了要求，可是复用性太差，既然你觉得你C语言最熟悉，那么就请封装一个复用性高的代码出来看看吧。
我想使用复用性非常强的C代码，可以方便移植，快速开发，例如下面编写的mylib库函数：
#include "s3c2440_gpio.h"
int main(void)
{
Reset_gpio(OUT, GPIOF,GPIO_PinSource4);
Set_gpio(OUT, GPIOF,GPIO_PinSource5);
Reset_gpio(OUT, GPIOF,GPIO_PinSource6);
return 0;
}
就是这样的代码，可以调用一个函数，达到指定IO输出高低电平或者设置模式。
s3c2440_gpio.c:
#include "s3c2440_gpio.h"
void Set_gpio(IOState new,GPIO_TypeDef* GPIO_InitStruct,uint16_t GPIO_PinSource)
{
if(new==OUT)
{
//CON复位值为0，配置为输出
GPIO_InitStruct->CON |=1<<GPIO_PinSource*2;/*乘法优先级高于左移*/
//DAT复位值udf
GPIO_InitStruct->DAT |=(1<<GPIO_PinSource);/*对应位清零，输出1*/
}
else if(new==IN)
{
//CON复位值为0，配置为输入
GPIO_InitStruct->CON &=(3<<GPIO_PinSource*2);/*乘法优先级高于左移*/
}
else
{
/*预留*/
}
}
void Reset_gpio(IOState new,GPIO_TypeDef* GPIO_InitStruct,uint16_t GPIO_PinSource)
{
if(new==OUT)
{
//CON复位值为0，配置为输出
GPIO_InitStruct->CON |=1<<GPIO_PinSource*2;/*乘法优先级高于左移*/
GPIO_InitStruct->DAT &=~(1<<GPIO_PinSource);/*对应位清零，输出0,低电平*/
}
}
s3c2440_gpio.h:
#ifndef _S3C2440_GPIO_H_
#define _S3C2440_GPIO_H_
typedef unsigned char uint8_t;
typedef unsigned short int uint16_t;
typedef unsigned int uint32_t;
#define __IO volatile
typedef struct
{
__IO uint32_t CON;
__IO uint32_t DAT;
__IO uint32_t UP;
__IO uint32_t Reserved;
} GPIO_TypeDef;
typedef enum
{
IN = 0,
OUT = 1,
EINT=2
} IOState;
#define GPIO_PinSource0 ((uint8_t)0x00)
#define GPIO_PinSource1 ((uint8_t)0x01)
#define GPIO_PinSource2 ((uint8_t)0x02)
#define GPIO_PinSource3 ((uint8_t)0x03)
#define GPIO_PinSource4 ((uint8_t)0x04)
#define GPIO_PinSource5 ((uint8_t)0x05)
#define GPIO_PinSource6 ((uint8_t)0x06)
#define GPIO_PinSource7 ((uint8_t)0x07)
#define GPIOA_BASE (0x56000000)
#define GPIOB_BASE (0x56000010)
#define GPIOC_BASE (0x56000020)
#define GPIOD_BASE (0x56000030)
#define GPIOE_BASE (0x56000040)
#define GPIOF_BASE (0x56000050)
#define GPIOG_BASE (0x56000060)
#define GPIOH_BASE (0x56000070)
#define GPIOJ_BASE (0x560000d0)
#define GPIOA ((GPIO_TypeDef *) GPIOA_BASE)
#define GPIOB ((GPIO_TypeDef *) GPIOB_BASE)
#define GPIOC ((GPIO_TypeDef *) GPIOC_BASE)
#define GPIOD ((GPIO_TypeDef *) GPIOD_BASE)
#define GPIOE ((GPIO_TypeDef *) GPIOE_BASE)
#define GPIOF ((GPIO_TypeDef *) GPIOF_BASE)
#define GPIOG ((GPIO_TypeDef *) GPIOG_BASE)
#define GPIOH ((GPIO_TypeDef *) GPIOH_BASE)
#define GPIOJ ((GPIO_TypeDef *) GPIOJ_BASE)
void Set_gpio(IOState new,GPIO_TypeDef* GPIO_InitStruct,uint16_t GPIO_PinSource);
void Reset_gpio(IOState new,GPIO_TypeDef* GPIO_InitStruct,uint16_t GPIO_PinSource);
#endif /*s3c2440_gpio.h*/
编写出这样的库函数需要有过库函数编程经验并且具备一定的C语言基础和思维。
再看看加了-g选项也就是调试信息的反汇编：
led.elf: file format elf32-littlearm
Disassembly of section .text:
<_start>:
.global _start
_start:
ldr sp,=4096 //nandflash启动,设置栈
0: e3a0da01 mov sp, #4096 ; 0x1000
//调用main函数
bl main
4: eb000000 bl c <main>
<halt>:
halt:
b halt
8: eafffffe b 8 <halt>
0000000c <main>:
#include "s3c2440_gpio.h"
int main(void)
{
c: e1a0c00d mov ip, sp
10: e92dd800 stmdb sp!, {fp, ip, lr, pc}
14: e24cb004 sub fp, ip, #4 ; 0x4
Reset_gpio(OUT, GPIOF,GPIO_PinSource4);
18: e3a00001 mov r0, #1 ; 0x1
1c: e3a01456 mov r1, #1442840576 ; 0x56000000
20: e2811050 add r1, r1, #80 ; 0x50
24: e3a02004 mov r2, #4 ; 0x4
28: eb000042 bl 138 <Reset_gpio>
Set_gpio(OUT, GPIOF,GPIO_PinSource5);
2c: e3a00001 mov r0, #1 ; 0x1
30: e3a01456 mov r1, #1442840576 ; 0x56000000
34: e2811050 add r1, r1, #80 ; 0x50
38: e3a02005 mov r2, #5 ; 0x5
3c: eb000007 bl 60 <Set_gpio>
Reset_gpio(OUT, GPIOF,GPIO_PinSource6);
40: e3a00001 mov r0, #1 ; 0x1
44: e3a01456 mov r1, #1442840576 ; 0x56000000
48: e2811050 add r1, r1, #80 ; 0x50
4c: e3a02006 mov r2, #6 ; 0x6
50: eb000038 bl 138 <Reset_gpio>
return 0;
54: e3a03000 mov r3, #0 ; 0x0
}
58: e1a00003 mov r0, r3
5c: e89da800 ldmia sp, {fp, sp, pc}
<Set_gpio>:
#include "s3c2440_gpio.h"
void Set_gpio(IOState new,GPIO_TypeDef* GPIO_InitStruct,uint16_t GPIO_PinSource)
{
60: e1a0c00d mov ip, sp
64: e92dd800 stmdb sp!, {fp, ip, lr, pc}
68: e24cb004 sub fp, ip, #4 ; 0x4
6c: e24dd00c sub sp, sp, #12 ; 0xc
70: e50b0010 str r0, [fp, #-16]
74: e50b1014 str r1, [fp, #-20]
78: e1a03002 mov r3, r2
7c: e54b3016 strb r3, [fp, #-22]
80: e1a03443 mov r3, r3, asr #8
84: e54b3015 strb r3, [fp, #-21]
if(new==OUT)
88: e51b3010 ldr r3, [fp, #-16]
8c: e3530001 cmp r3, #1 ; 0x1
90: 1a000017 bne f4 <Set_gpio+0x94>
{
//CON复位值为0，配置为输出
GPIO_InitStruct->CON |=1<<GPIO_PinSource*2;/*乘法优先级高于左移*/
94: e51b0014 ldr r0, [fp, #-20]
98: e51b1014 ldr r1, [fp, #-20]
9c: e24b3016 sub r3, fp, #22 ; 0x16
a0: e5d32000 ldrb r2, [r3]
a4: e5d33001 ldrb r3, [r3, #1]
a8: e1823403 orr r3, r2, r3, lsl #8
ac: e1a02083 mov r2, r3, lsl #1
b0: e3a03001 mov r3, #1 ; 0x1
b4: e1a02213 mov r2, r3, lsl r2
b8: e5913000 ldr r3, [r1]
bc: e1833002 orr r3, r3, r2
c0: e5803000 str r3, [r0]
//DAT复位值udf
GPIO_InitStruct->DAT |=(1<<GPIO_PinSource);/*对应位清零，输出1*/
c4: e51b1014 ldr r1, [fp, #-20]
c8: e51b0014 ldr r0, [fp, #-20]
cc: e24b3016 sub r3, fp, #22 ; 0x16
d0: e5d32000 ldrb r2, [r3]
d4: e5d33001 ldrb r3, [r3, #1]
d8: e1822403 orr r2, r2, r3, lsl #8
dc: e3a03001 mov r3, #1 ; 0x1
e0: e1a02213 mov r2, r3, lsl r2
e4: e5903004 ldr r3, [r0, #4]
e8: e1833002 orr r3, r3, r2
ec: e5813004 str r3, [r1, #4]
f0: ea00000e b 130 <Set_gpio+0xd0>
}
else if(new==IN)
f4: e51b3010 ldr r3, [fp, #-16]
f8: e3530000 cmp r3, #0 ; 0x0
fc: 1a00000b bne 130 <Set_gpio+0xd0>
{
//CON复位值为0，配置为输入
GPIO_InitStruct->CON &=(3<<GPIO_PinSource*2);/*乘法优先级高于左移*/
100: e51b0014 ldr r0, [fp, #-20]
104: e51b1014 ldr r1, [fp, #-20]
108: e24b3016 sub r3, fp, #22 ; 0x16
10c: e5d32000 ldrb r2, [r3]
110: e5d33001 ldrb r3, [r3, #1]
114: e1823403 orr r3, r2, r3, lsl #8
118: e1a02083 mov r2, r3, lsl #1
11c: e3a03003 mov r3, #3 ; 0x3
120: e1a02213 mov r2, r3, lsl r2
124: e5913000 ldr r3, [r1]
128: e0033002 and r3, r3, r2
12c: e5803000 str r3, [r0]
}
else
{
/*预留*/
}
}
130: e24bd00c sub sp, fp, #12 ; 0xc
134: e89da800 ldmia sp, {fp, sp, pc}
<Reset_gpio>:
void Reset_gpio(IOState new,GPIO_TypeDef* GPIO_InitStruct,uint16_t GPIO_PinSource)
{
138: e1a0c00d mov ip, sp
13c: e92dd800 stmdb sp!, {fp, ip, lr, pc}
140: e24cb004 sub fp, ip, #4 ; 0x4
144: e24dd00c sub sp, sp, #12 ; 0xc
148: e50b0010 str r0, [fp, #-16]
14c: e50b1014 str r1, [fp, #-20]
150: e1a03002 mov r3, r2
154: e54b3016 strb r3, [fp, #-22]
158: e1a03443 mov r3, r3, asr #8
15c: e54b3015 strb r3, [fp, #-21]
if(new==OUT)
160: e51b3010 ldr r3, [fp, #-16]
164: e3530001 cmp r3, #1 ; 0x1
168: 1a000017 bne 1cc <Reset_gpio+0x94>
{
//CON复位值为0，配置为输出
GPIO_InitStruct->CON |=1<<GPIO_PinSource*2;/*乘法优先级高于左移*/
16c: e51b0014 ldr r0, [fp, #-20]
170: e51b1014 ldr r1, [fp, #-20]
174: e24b3016 sub r3, fp, #22 ; 0x16
178: e5d32000 ldrb r2, [r3]
17c: e5d33001 ldrb r3, [r3, #1]
180: e1823403 orr r3, r2, r3, lsl #8
184: e1a02083 mov r2, r3, lsl #1
188: e3a03001 mov r3, #1 ; 0x1
18c: e1a02213 mov r2, r3, lsl r2
190: e5913000 ldr r3, [r1]
194: e1833002 orr r3, r3, r2
198: e5803000 str r3, [r0]
GPIO_InitStruct->DAT &=~(1<<GPIO_PinSource);/*对应位清零，输出0,低电平*/
19c: e51b0014 ldr r0, [fp, #-20]
1a0: e51b1014 ldr r1, [fp, #-20]
1a4: e24b3016 sub r3, fp, #22 ; 0x16
1a8: e5d32000 ldrb r2, [r3]
1ac: e5d33001 ldrb r3, [r3, #1]
1b0: e1822403 orr r2, r2, r3, lsl #8
1b4: e3a03001 mov r3, #1 ; 0x1
1b8: e1a03213 mov r3, r3, lsl r2
1bc: e1e02003 mvn r2, r3
1c0: e5913004 ldr r3, [r1, #4]
1c4: e0033002 and r3, r3, r2
1c8: e5803004 str r3, [r0, #4]
}
}
1cc: e24bd00c sub sp, fp, #12 ; 0xc
1d0: e89da800 ldmia sp, {fp, sp, pc}
Disassembly of section .comment:
<.comment>:
0: 43434700 cmpmi r3, #0 ; 0x0
4: 4728203a undefined
8: 2029554e eorcs r5, r9, lr, asr #10
c: 2e342e33 mrccs 14, 1, r2, cr4, cr3, {1}
10: 47000035 smladxmi r0, r5, r0, r0
14: 203a4343 eorcss r4, sl, r3, asr #6
18: 554e4728 strplb r4, [lr, #-1832]
1c: 2e332029 cdpcs 0, 3, cr2, cr3, cr9, {1}
20: 00352e34 eoreqs r2, r5, r4, lsr lr
Disassembly of section .debug_aranges:
<.debug_aranges>:
0: 0000001c andeq r0, r0, ip, lsl r0
4: 00000002 andeq r0, r0, r2
8: 00040000 andeq r0, r4, r0
...
14: 0000000c andeq r0, r0, ip
...
20: 0000001c andeq r0, r0, ip, lsl r0
24: 003a0002 eoreqs r0, sl, r2
28: 00040000 andeq r0, r4, r0
2c: 00000000 andeq r0, r0, r0
30: 0000000c andeq r0, r0, ip
34: 00000054 andeq r0, r0, r4, asr r0
...
40: 0000001c andeq r0, r0, ip, lsl r0
44: 00c90002 sbceq r0, r9, r2
48: 00040000 andeq r0, r4, r0
4c: 00000000 andeq r0, r0, r0
50: 00000060 andeq r0, r0, r0, rrx
54: 00000174 andeq r0, r0, r4, ror r1
...
Disassembly of section .debug_pubnames:
<.debug_pubnames>:
0: 00000017 andeq r0, r0, r7, lsl r0
4: 003a0002 eoreqs r0, sl, r2
8: 008f0000 addeq r0, pc, r0
c: 006f0000 rsbeq r0, pc, r0
10: 616d0000 cmnvs sp, r0
14: 00006e69 andeq r6, r0, r9, ror #28
18: 2a000000 bcs 20 <main+0x14>
1c: 02000000 andeq r0, r0, #0 ; 0x0
20: 0000c900 andeq ip, r0, r0, lsl #18
24: 0001c100 andeq ip, r1, r0, lsl #2
28: 00012e00 andeq r2, r1, r0, lsl #28
2c: 74655300 strvcbt r5, [r5], #-768
30: 6970675f ldmvsdb r0!, {r0, r1, r2, r3, r4, r6, r8, r9, sl, sp, lr}^
34: 017b006f cmneq fp, pc, rrx
38: 65520000 ldrvsb r0, [r2]
3c: 5f746573 swipl 0x00746573
40: 6f697067 swivs 0x00697067
44: 00000000 andeq r0, r0, r0
...
Disassembly of section .debug_info:
<.debug_info>:
0: 00000036 andeq r0, r0, r6, lsr r0
4: 00000002 andeq r0, r0, r2
8: 01040000 tsteq r4, r0
...
14: 0000000c andeq r0, r0, ip
18: 72617473 rsbvc r7, r1, #1929379840 ; 0x73000000
1c: 00532e74 subeqs r2, r3, r4, ror lr
20: 6d6f682f stcvsl 8, cr6, [pc, #-188]!
24: 68732f65 ldmvsda r3!, {r0, r2, r5, r6, r8, r9, sl, fp, sp}^
28: 00657261 rsbeq r7, r5, r1, ror #4
2c: 20554e47 subcss r4, r5, r7, asr #28
30: 32205341 eorcc r5, r0, #67108865 ; 0x4000001
34: 0035312e eoreqs r3, r5, lr, lsr #2
38: 008b8001 addeq r8, fp, r1
3c: 00020000 andeq r0, r2, r0
40: 00000014 andeq r0, r0, r4, lsl r0
44: 00360104 eoreqs r0, r6, r4, lsl #2
48: 00600000 rsbeq r0, r0, r0
4c: 000c0000 andeq r0, ip, r0
50: 4e470000 cdpmi 0, 4, cr0, cr7, cr0, {0}
54: 20432055 subcs r2, r3, r5, asr r0
58: 2e342e33 mrccs 14, 1, r2, cr4, cr3, {1}
5c: 6d010035 stcvs 0, cr0, [r1, #-212]
60: 2e6e6961 cdpcs 9, 6, cr6, cr14, cr1, {3}
64: 682f0063 stmvsda pc!, {r0, r1, r5, r6}
68: 2f656d6f swics 0x00656d6f
6c: 72616873 rsbvc r6, r1, #7536640 ; 0x730000
70: 75020065 strvc r0, [r2, #-101]
74: 6769736e strvsb r7, [r9, -lr, ror #6]!
78: 2064656e rsbcs r6, r4, lr, ror #10
7c: 72616863 rsbvc r6, r1, #6488064 ; 0x630000
80: 02080100 andeq r0, r8, #0 ; 0x0
84: 726f6873 rsbvc r6, pc, #7536640 ; 0x730000
88: 6e752074 mrcvs 0, 3, r2, cr5, cr4, {3}
8c: 6e676973 mcrvs 9, 3, r6, cr7, cr3, {3}
90: 69206465 stmvsdb r0!, {r0, r2, r5, r6, sl, sp, lr}
94: 0200746e andeq r7, r0, #1845493760 ; 0x6e000000
98: 6e750207 cdpvs 2, 7, cr0, cr5, cr7, {0}
9c: 6e676973 mcrvs 9, 3, r6, cr7, cr3, {3}
a0: 69206465 stmvsdb r0!, {r0, r2, r5, r6, sl, sp, lr}
a4: 0400746e streq r7, [r0], #-1134
a8: 6d010307 stcvs 3, cr0, [r1, #-28]
ac: 006e6961 rsbeq r6, lr, r1, ror #18
b0: 87010301 strhi r0, [r1, -r1, lsl #6]
b4: 0c000000 stceq 0, cr0, [r0], {0}
b8: 60000000 andvs r0, r0, r0
bc: 01000000 tsteq r0, r0
c0: 6e69025b mcrvs 2, 3, r0, cr9, cr11, {2}
c4: 05040074 streq r0, [r4, #-116]
c8: 0001bd00 andeq fp, r1, r0, lsl #26
cc: 4a000200 bmi 8d4 <Reset_gpio+0x79c>
d0: 04000000 streq r0, [r0]
d4: 00006c01 andeq r6, r0, r1, lsl #24
d8: 0001d400 andeq sp, r1, r0, lsl #8
dc: 00006000 andeq r6, r0, r0
e0: 554e4700 strplb r4, [lr, #-1792]
e4: 33204320 teqcc r0, #-2147483648 ; 0x80000000
e8: 352e342e strcc r3, [lr, #-1070]!
ec: 33730100 cmncc r3, #0 ; 0x0
f0: 34343263 ldrcct r3, [r4], #-611
f4: 70675f30 rsbvc r5, r7, r0, lsr pc
f8: 632e6f69 teqvs lr, #420 ; 0x1a4
fc: 6f682f00 swivs 0x00682f00
100: 732f656d teqvc pc, #457179136 ; 0x1b400000
104: 65726168 ldrvsb r6, [r2, #-360]!
108: 6e750200 cdpvs 2, 7, cr0, cr5, cr0, {0}
10c: 6e676973 mcrvs 9, 3, r6, cr7, cr3, {3}
110: 63206465 teqvs r0, #1694498816 ; 0x65000000
114: 00726168 rsbeqs r6, r2, r8, ror #2
118: 75030801 strvc r0, [r3, #-2049]
11c: 31746e69 cmncc r4, r9, ror #28
120: 00745f36 rsbeqs r5, r4, r6, lsr pc
124: 00610402 rsbeq r0, r1, r2, lsl #8
128: 73020000 tstvc r2, #0 ; 0x0
12c: 74726f68 ldrvcbt r6, [r2], #-3944
130: 736e7520 cmnvc lr, #134217728 ; 0x8000000
134: 656e6769 strvsb r6, [lr, #-1897]!
138: 6e692064 cdpvs 0, 6, cr2, cr9, cr4, {3}
13c: 07020074 smlsdxeq r2, r4, r0, r0
140: 6e697503 cdpvs 5, 6, cr7, cr9, cr3, {0}
144: 5f323374 swipl 0x00323374
148: 05020074 streq r0, [r2, #-116]
14c: 00000087 andeq r0, r0, r7, lsl #1
150: 736e7502 cmnvc lr, #8388608 ; 0x800000
154: 656e6769 strvsb r6, [lr, #-1897]!
158: 6e692064 cdpvs 0, 6, cr2, cr9, cr4, {3}
15c: 07040074 smlsdxeq r4, r4, r0, r0
160: 0000dc04 andeq sp, r0, r4, lsl #24
164: 0d021000 stceq 0, cr1, [r2]
168: 4e4f4305 cdpmi 3, 4, cr4, cr15, cr5, {0}
16c: dc090200 sfmle f0, 4, [r9], {0}
170: 02000000 andeq r0, r0, #0 ; 0x0
174: 44050023 strmi r0, [r5], #-35
178: 02005441 andeq r5, r0, #1090519040 ; 0x41000000
17c: 0000e10a andeq lr, r0, sl, lsl #2
180: 04230200 streqt r0, [r3], #-512
184: 00505505 subeqs r5, r0, r5, lsl #10
188: 00e60b02 rsceq r0, r6, r2, lsl #22
18c: 23020000 tstcs r2, #0 ; 0x0
190: 65520508 ldrvsb r0, [r2, #-1288]
194: 76726573 undefined
198: 02006465 andeq r6, r0, #1694498816 ; 0x65000000
19c: 0000eb0c andeq lr, r0, ip, lsl #22
1a0: 0c230200 sfmeq f0, 4, [r3]
1a4: 00770600 rsbeqs r0, r7, r0, lsl #12
1a8: 77060000 strvc r0, [r6, -r0]
1ac: 06000000 streq r0, [r0], -r0
1b0: 00000077 andeq r0, r0, r7, ror r0
1b4: 00007706 andeq r7, r0, r6, lsl #14
1b8: 50470300 subpl r0, r7, r0, lsl #6
1bc: 545f4f49 ldrplb r4, [pc], #3913 ; 1c4 <Reset_gpio+0x8c>
1c0: 44657079 strmibt r7, [r5], #-121
1c4: 02006665 andeq r6, r0, #105906176 ; 0x6500000
1c8: 0000970d andeq r9, r0, sp, lsl #14
1cc: 011f0700 tsteq pc, r0, lsl #14
1d0: 02040000 andeq r0, r4, #0 ; 0x0
1d4: 4e490810 mcrmi 8, 2, r0, cr9, cr0, {0}
1d8: 4f080000 swimi 0x00080000
1dc: 01005455 tsteq r0, r5, asr r4
1e0: 4e494508 cdpmi 5, 4, cr4, cr9, cr8, {0}
1e4: 00020054 andeq r0, r2, r4, asr r0
1e8: 534f4903 cmppl pc, #49152 ; 0xc000
1ec: 65746174 ldrvsb r6, [r4, #-372]!
1f0: 04140200 ldreq r0, [r4], #-512
1f4: 09000001 stmeqdb r0, {r0}
1f8: 00000175 andeq r0, r0, r5, ror r1
1fc: 74655301 strvcbt r5, [r5], #-769
200: 6970675f ldmvsdb r0!, {r0, r1, r2, r3, r4, r6, r8, r9, sl, sp, lr}^
204: 0401006f streq r0, [r1], #-111
208: 00006001 andeq r6, r0, r1
20c: 00013800 andeq r3, r1, r0, lsl #16
210: 0a5b0100 beq 16c0618 <__bss_end__+0x16b8444>
214: 0077656e rsbeqs r6, r7, lr, ror #10
218: 011f0301 tsteq pc, r1, lsl #6
21c: 91020000 tstls r2, r0
220: 000f0b70 andeq r0, pc, r0, ror fp
224: 03010000 tsteq r1, #0 ; 0x0
228: 00000175 andeq r0, r0, r5, ror r1
22c: 0b6c9102 bleq 1b2463c <__bss_end__+0x1b1c468>
230: 00000000 andeq r0, r0, r0
234: 00510301 subeqs r0, r1, r1, lsl #6
238: 91020000 tstls r2, r0
23c: 040c006a streq r0, [ip], #-106
240: 000000f0 streqd r0, [r0], -r0
244: 6552010d ldrvsb r0, [r2, #-269]
248: 5f746573 swipl 0x00746573
24c: 6f697067 swivs 0x00697067
250: 01180100 tsteq r8, r0, lsl #2
254: 00000138 andeq r0, r0, r8, lsr r1
258: 000001d4 ldreqd r0, [r0], -r4
25c: 6e0a5b01 fmacdvs d5, d10, d1
260: 01007765 tsteq r0, r5, ror #14
264: 00011f17 andeq r1, r1, r7, lsl pc
268: 70910200 addvcs r0, r1, r0, lsl #4
26c: 00000f0b andeq r0, r0, fp, lsl #30
270: 75170100 ldrvc r0, [r7, #-256]
274: 02000001 andeq r0, r0, #1 ; 0x1
278: 000b6c91 muleq fp, r1, ip
27c: 01000000 tsteq r0, r0
280: 00005117 andeq r5, r0, r7, lsl r1
284: 6a910200 bvs fe440a8c <__bss_end__+0xfe4388b8>
...
Disassembly of section .debug_abbrev:
<.debug_abbrev>:
0: 10001101 andne r1, r0, r1, lsl #2
4: 12011106 andne r1, r1, #-2147483647 ; 0x80000001
8: 1b080301 blne 200c14 <__bss_end__+0x1f8a40>
c: 13082508 tstne r8, #33554432 ; 0x2000000
10: 00000005 andeq r0, r0, r5
14: 10011101 andne r1, r1, r1, lsl #2
18: 11011206 tstne r1, r6, lsl #4
1c: 13082501 tstne r8, #4194304 ; 0x400000
20: 1b08030b blne 200c54 <__bss_end__+0x1f8a80>
24: 02000008 andeq r0, r0, #8 ; 0x8
28: 08030024 stmeqda r3, {r2, r5}
2c: 0b3e0b0b bleq f82c60 <__bss_end__+0xf7aa8c>
30: 2e030000 cdpcs 0, 0, cr0, cr3, cr0, {0}
34: 030c3f00 tsteq ip, #0 ; 0x0
38: 3b0b3a08 blcc 2ce860 <__bss_end__+0x2c668c>
3c: 490c270b stmmidb ip, {r0, r1, r3, r8, r9, sl, sp}
40: 12011113 andne r1, r1, #-1073741820 ; 0xc0000004
44: 000a4001 andeq r4, sl, r1
48: 11010000 tstne r1, r0
4c: 12061001 andne r1, r6, #1 ; 0x1
50: 25011101 strcs r1, [r1, #-257]
54: 030b1308 tsteq fp, #536870912 ; 0x20000000
58: 00081b08 andeq r1, r8, r8, lsl #22
5c: 00240200 eoreq r0, r4, r0, lsl #4
60: 0b0b0803 bleq 2c2074 <__bss_end__+0x2b9ea0>
64: 00000b3e andeq r0, r0, lr, lsr fp
68: 03001603 tsteq r0, #3145728 ; 0x300000
6c: 3b0b3a08 blcc 2ce894 <__bss_end__+0x2c66c0>
70: 0013490b andeqs r4, r3, fp, lsl #18
74: 01130400 tsteq r3, r0, lsl #8
78: 0b0b1301 bleq 2c4c84 <__bss_end__+0x2bcab0>
7c: 0b3b0b3a bleq ec2d6c <__bss_end__+0xebab98>
80: 0d050000 stceq 0, cr0, [r5]
84: 3a080300 bcc 200c8c <__bss_end__+0x1f8ab8>
88: 490b3b0b stmmidb fp, {r0, r1, r3, r8, r9, fp, ip, sp}
8c: 000a3813 andeq r3, sl, r3, lsl r8
90: 00350600 eoreqs r0, r5, r0, lsl #12
94: 00001349 andeq r1, r0, r9, asr #6
98: 01010407 tsteq r1, r7, lsl #8
9c: 3a0b0b13 bcc 2c2cf0 <__bss_end__+0x2bab1c>
a0: 000b3b0b andeq r3, fp, fp, lsl #22
a4: 00280800 eoreq r0, r8, r0, lsl #16
a8: 0d1c0803 ldceq 8, cr0, [ip, #-12]
ac: 2e090000 cdpcs 0, 0, cr0, cr9, cr0, {0}
b0: 3f130101 swicc 0x00130101
b4: 3a08030c bcc 200cec <__bss_end__+0x1f8b18>
b8: 270b3b0b strcs r3, [fp, -fp, lsl #22]
bc: 1201110c andne r1, r1, #3 ; 0x3
c0: 000a4001 andeq r4, sl, r1
c4: 00050a00 andeq r0, r5, r0, lsl #20
c8: 0b3a0803 bleq e820dc <__bss_end__+0xe79f08>
cc: 13490b3b cmpne r9, #60416 ; 0xec00
d0: 00000a02 andeq r0, r0, r2, lsl #20
d4: 0300050b tsteq r0, #46137344 ; 0x2c00000
d8: 3b0b3a0e blcc 2ce918 <__bss_end__+0x2c6744>
dc: 0213490b andeqs r4, r3, #180224 ; 0x2c000
e0: 0c00000a stceq 0, cr0, [r0], {10}
e4: 0b0b000f bleq 2c0128 <__bss_end__+0x2b7f54>
e8: 00001349 andeq r1, r0, r9, asr #6
ec: 3f012e0d swicc 0x00012e0d
f0: 3a08030c bcc 200d28 <__bss_end__+0x1f8b54>
f4: 270b3b0b strcs r3, [fp, -fp, lsl #22]
f8: 1201110c andne r1, r1, #3 ; 0x3
fc: 000a4001 andeq r4, sl, r1
...
Disassembly of section .debug_line:
<.debug_line>:
0: 00000032 andeq r0, r0, r2, lsr r0
4: 001b0002 andeqs r0, fp, r2
8: 01020000 tsteq r2, r0
c: 000a0efb streqd r0, [sl], -fp
10: 01010101 tsteq r1, r1, lsl #2
14: 01000000 tsteq r0, r0
18: 61747300 cmnvs r4, r0, lsl #6
1c: 532e7472 teqpl lr, #1912602624 ; 0x72000000
20: 00000000 andeq r0, r0, r0
24: 02050000 andeq r0, r5, #0 ; 0x0
28: 00000000 andeq r0, r0, r0
2c: 2d010903 stccs 9, cr0, [r1, #-12]
30: 0002022e andeq r0, r2, lr, lsr #4
34: 00320101 eoreqs r0, r2, r1, lsl #2
38: 00020000 andeq r0, r2, r0
3c: 0000001a andeq r0, r0, sl, lsl r0
40: 0efb0102 cdpeq 1, 15, cr0, cr11, cr2, {0}
44: 0101000a tsteq r1, sl
48: 00000101 andeq r0, r0, r1, lsl #2
4c: 6d000100 stfvss f0, [r0]
50: 2e6e6961 cdpcs 9, 6, cr6, cr14, cr1, {3}
54: 00000063 andeq r0, r0, r3, rrx
58: 05000000 streq r0, [r0]
5c: 00000c02 andeq r0, r0, r2, lsl #24
60: 9c651100 stflse f1, [r5]
64: 022c9c9c eoreq r9, ip, #39936 ; 0x9c00
68: 01010004 tsteq r1, r4
6c: 00000059 andeq r0, r0, r9, asr r0
70: 00340002 eoreqs r0, r4, r2
74: 01020000 tsteq r2, r0
78: 000a0efb streqd r0, [sl], -fp
7c: 01010101 tsteq r1, r1, lsl #2
80: 01000000 tsteq r0, r0
84: 63337300 teqvs r3, #0 ; 0x0
88: 30343432 eorccs r3, r4, r2, lsr r4
8c: 6970675f ldmvsdb r0!, {r0, r1, r2, r3, r4, r6, r8, r9, sl, sp, lr}^
90: 00632e6f rsbeq r2, r3, pc, ror #28
94: 73000000 tstvc r0, #0 ; 0x0
98: 34326333 ldrcct r6, [r2], #-819
9c: 675f3034 smmlarvs pc, r4, r0, r3
a0: 2e6f6970 mcrcs 9, 3, r6, cr15, cr0, {3}
a4: 00000068 andeq r0, r0, r8, rrx
a8: 05000000 streq r0, [r0]
ac: 00006002 andeq r6, r0, r2
b0: 3a081200 bcc 2048b8 <__bss_end__+0x1fc6e4>
b4: 08730866 ldmeqda r3!, {r1, r2, r5, r6, fp}^
b8: 77086673 smlsdxvc r8, r3, r6, r6
bc: 663a084a ldrvst r0, [sl], -sl, asr #16
c0: 73087208 tstvc r8, #-2147483648 ; 0x80000000
c4: 01000402 tsteq r0, r2, lsl #8
c8: Address 0xc8 is out of bounds.
Disassembly of section .debug_frame:
<.debug_frame>:
0: 0000000c andeq r0, r0, ip
4: ffffffff swinv 0x00ffffff
8: 7c010001 stcvc 0, cr0, [r1], {1}
c: 000d0c0e andeq r0, sp, lr, lsl #24
10: 0000001c andeq r0, r0, ip, lsl r0
14: 00000000 andeq r0, r0, r0
18: 0000000c andeq r0, r0, ip
1c: 00000054 andeq r0, r0, r4, asr r0
20: 440c0d44 strmi r0, [ip], #-3396
24: 038d028e orreq r0, sp, #-536870904 ; 0xe0000008
28: 0c44048b cfstrdeq mvd0, [r4], {139}
2c: 0000040b andeq r0, r0, fp, lsl #8
30: 0000000c andeq r0, r0, ip
34: ffffffff swinv 0x00ffffff
38: 7c010001 stcvc 0, cr0, [r1], {1}
3c: 000d0c0e andeq r0, sp, lr, lsl #24
40: 0000001c andeq r0, r0, ip, lsl r0
44: 00000030 andeq r0, r0, r0, lsr r0
48: 00000060 andeq r0, r0, r0, rrx
4c: 000000d8 ldreqd r0, [r0], -r8
50: 440c0d44 strmi r0, [ip], #-3396
54: 038d028e orreq r0, sp, #-536870904 ; 0xe0000008
58: 0c44048b cfstrdeq mvd0, [r4], {139}
5c: 0000040b andeq r0, r0, fp, lsl #8
60: 0000001c andeq r0, r0, ip, lsl r0
64: 00000030 andeq r0, r0, r0, lsr r0
68: 00000138 andeq r0, r0, r8, lsr r1
6c: 0000009c muleq r0, ip, r0
70: 440c0d44 strmi r0, [ip], #-3396
74: 038d028e orreq r0, sp, #-536870904 ; 0xe0000008
78: 0c44048b cfstrdeq mvd0, [r4], {139}
7c: 0000040b andeq r0, r0, fp, lsl #8
Disassembly of section .debug_str:
<.debug_str>:
0: 4f495047 swimi 0x00495047
4: 6e69505f mcrvs 0, 3, r5, cr9, cr15, {2}
8: 72756f53 rsbvcs r6, r5, #332 ; 0x14c
c: 47006563 strmi r6, [r0, -r3, ror #10]
10: 5f4f4950 swipl 0x004f4950
14: 74696e49 strvcbt r6, [r9], #-3657
18: 75727453 ldrvcb r7, [r2, #-1107]!
1c: Address 0x1c is out of bounds.
Makefile如下：
all:
arm-linux-gcc -c -g -o s3c2440_gpio.o s3c2440_gpio.c
arm-linux-gcc -c -g -o main.o main.c
arm-linux-gcc -c -g -o start.o start.S
arm-linux-ld -Ttext 0 start.o main.o s3c2440_gpio.o -o led.elf
arm-linux-objcopy -O binary -S led.elf led.bin
arm-linux-objdump -S -D led.elf > led.dis
clean:
rm *.bin *.o *.elf *.dis
这个程序烧录进单板是可以点亮4和6的，但是这还存在一个潜在问题，看cpu手册：
看门狗默认是打开的，所以程序运行一段时间会复位，但是上面没有加入LED闪烁，所以看不出来，现在更改启动文件的汇编，把看门狗关闭：
上面的库函数还需要根据寄存器不断配置优化，我只是做出一个模子，这样给大家一个参考，就是通过一个通用的函数，给不同的引脚就让处理器做不同的事。
现在给出最终版（当然，库函数需要根据学习得深入不断优化）：
包括关闭看门狗，自己写的输入输出设置库函数以及读取输入引脚库函数，这是根据以前STM32库函数开发经验，自己写库应用在s3c2440上。
启动汇编如上图所示，这里贴出c代码：
头文件：
#ifndef _S3C2440_GPIO_H_
#define _S3C2440_GPIO_H_
typedef unsigned char uint8_t;
typedef unsigned short int uint16_t;
typedef unsigned int uint32_t;
#define __IO volatile
typedef struct
{
__IO uint32_t CON;
__IO uint32_t DAT;
__IO uint32_t UP;
__IO uint32_t Reserved;
} GPIO_TypeDef;
typedef enum
{
IN = 0,
OUT = 1,
EINT=2
} IOState;
typedef enum
{
Bit_RESET = 0,
Bit_SET
}BitAction;
#define GPIO_Pin_0 ((uint16_t)0x0001) /*!< Pin 0 selected */
#define GPIO_Pin_1 ((uint16_t)0x0002) /*!< Pin 1 selected */
#define GPIO_Pin_2 ((uint16_t)0x0004) /*!< Pin 2 selected */
#define GPIO_Pin_3 ((uint16_t)0x0008) /*!< Pin 3 selected */
#define GPIO_Pin_4 ((uint16_t)0x0010) /*!< Pin 4 selected */
#define GPIO_Pin_5 ((uint16_t)0x0020) /*!< Pin 5 selected */
#define GPIO_Pin_6 ((uint16_t)0x0040) /*!< Pin 6 selected */
#define GPIO_Pin_7 ((uint16_t)0x0080) /*!< Pin 7 selected */
#define GPIO_Pin_8 ((uint16_t)0x0100) /*!< Pin 8 selected */
#define GPIO_Pin_9 ((uint16_t)0x0200) /*!< Pin 9 selected */
#define GPIO_Pin_10 ((uint16_t)0x0400) /*!< Pin 10 selected */
#define GPIO_Pin_11 ((uint16_t)0x0800) /*!< Pin 11 selected */
#define GPIO_Pin_12 ((uint16_t)0x1000) /*!< Pin 12 selected */
#define GPIO_Pin_13 ((uint16_t)0x2000) /*!< Pin 13 selected */
#define GPIO_Pin_14 ((uint16_t)0x4000) /*!< Pin 14 selected */
#define GPIO_Pin_15 ((uint16_t)0x8000) /*!< Pin 15 selected */
#define GPIO_Pin_All ((uint16_t)0xFFFF) /*!< All pins selected */
#define GPIO_PinSource0 ((uint8_t)0x00)
#define GPIO_PinSource1 ((uint8_t)0x01)
#define GPIO_PinSource2 ((uint8_t)0x02)
#define GPIO_PinSource3 ((uint8_t)0x03)
#define GPIO_PinSource4 ((uint8_t)0x04)
#define GPIO_PinSource5 ((uint8_t)0x05)
#define GPIO_PinSource6 ((uint8_t)0x06)
#define GPIO_PinSource7 ((uint8_t)0x07)
#define GPIOA_BASE (0x56000000)
#define GPIOB_BASE (0x56000010)
#define GPIOC_BASE (0x56000020)
#define GPIOD_BASE (0x56000030)
#define GPIOE_BASE (0x56000040)
#define GPIOF_BASE (0x56000050)
#define GPIOG_BASE (0x56000060)
#define GPIOH_BASE (0x56000070)
#define GPIOJ_BASE (0x560000d0)
#define GPIOA ((GPIO_TypeDef *) GPIOA_BASE)
#define GPIOB ((GPIO_TypeDef *) GPIOB_BASE)
#define GPIOC ((GPIO_TypeDef *) GPIOC_BASE)
#define GPIOD ((GPIO_TypeDef *) GPIOD_BASE)
#define GPIOE ((GPIO_TypeDef *) GPIOE_BASE)
#define GPIOF ((GPIO_TypeDef *) GPIOF_BASE)
#define GPIOG ((GPIO_TypeDef *) GPIOG_BASE)
#define GPIOH ((GPIO_TypeDef *) GPIOH_BASE)
#define GPIOJ ((GPIO_TypeDef *) GPIOJ_BASE)
void Set_gpio(IOState new,GPIO_TypeDef* GPIO_InitStruct,uint16_t GPIO_PinSource);
void Reset_gpio(IOState new,GPIO_TypeDef* GPIO_InitStruct,uint16_t GPIO_PinSource);
uint8_t ReadInput_gpio(GPIO_TypeDef* GPIO_InitStruct,uint16_t GPIO_Pin);
#endif /*s3c2440_gpio.h*/
这里要分清楚GPIO是Pin还是PinSource。
源文件（增加读取输入电平）
#include "s3c2440_gpio.h"
/*设置输入输出属性，默认输出高电平
*new：out,in分别代表输出，输入
*GPIO_InitStruct：GPIO A-J
*GPIO_PinSource：0-7
*以上参数的宏定义可根据手册完善
*/
void Set_gpio(IOState new,GPIO_TypeDef* GPIO_InitStruct,uint16_t GPIO_PinSource)
{
if(new==OUT)
{
//CON复位值为0，配置为输出
GPIO_InitStruct->CON |=1<<GPIO_PinSource*2;/*乘法优先级高于左移*/
//DAT复位值udf
GPIO_InitStruct->DAT |=(1<<GPIO_PinSource);/*对应位清零，输出1*/
}
else if(new==IN)
{
//CON复位值为0，配置为输入
GPIO_InitStruct->CON &=(3<<GPIO_PinSource*2);/*乘法优先级高于左移*/
}
else
{
/*预留*/
}
}
/*
*设置输出引脚输出低电平
*/
void Reset_gpio(IOState new,GPIO_TypeDef* GPIO_InitStruct,uint16_t GPIO_PinSource)
{
if(new==OUT)
{
//CON复位值为0，配置为输出
GPIO_InitStruct->CON |=1<<GPIO_PinSource*2;/*乘法优先级高于左移*/
GPIO_InitStruct->DAT &=~(1<<GPIO_PinSource);/*对应位清零，输出0,低电平*/
}
}
/*
*读取输入引脚的电平，返回值为0或者1,0代表低电平，1代表高电平
*该函数本可以增加一个参数完成输入输出的读取，但是考虑到STM32也是分开的，故这里也分开实现
*输出引脚的电平读取库函数暂时没写，因为目前只用到输入引脚读取，后面需要时就完善，其原理是一样的，
*/
uint8_t ReadInput_gpio(GPIO_TypeDef* GPIO_InitStruct,uint16_t GPIO_Pin)
{
uint8_t bitstatus = 0x00;
if((GPIO_InitStruct->DAT & GPIO_Pin )!=(uint32_t)Bit_RESET)
{
bitstatus=(uint8_t)Bit_SET;
}
else
{
bitstatus = (uint8_t)Bit_RESET;
}
return bitstatus;
}
#include "s3c2440_gpio.h"
void Delay(uint32_t count)
{
while(count--);
}
int main(void)
{
//配置GPIOF 0，2，GPIOG 3为输入模式
Set_gpio(IN, GPIOF,GPIO_PinSource0);
Set_gpio(IN, GPIOF,GPIO_PinSource2);
Set_gpio(IN, GPIOG,GPIO_PinSource3);
//点亮LED1然后熄灭
Reset_gpio(OUT, GPIOF,GPIO_PinSource4);
Delay(100000);
Set_gpio(OUT, GPIOF,GPIO_PinSource4);
Delay(100000);
//点亮LED2然后熄灭
Reset_gpio(OUT, GPIOF,GPIO_PinSource5);
Delay(100000);
Set_gpio(OUT, GPIOF,GPIO_PinSource5);
Delay(100000);
//点亮LED3然后熄灭
Reset_gpio(OUT, GPIOF,GPIO_PinSource6);
Delay(100000);
Set_gpio(OUT, GPIOF,GPIO_PinSource6);
Delay(100000);
//熄灭三盏LED灯
Set_gpio(OUT, GPIOF,GPIO_PinSource5);
Set_gpio(OUT, GPIOF,GPIO_PinSource4);
while (1)
{
//如果按键3按下，则为低电平，就点亮LED3
if(ReadInput_gpio(GPIOF,GPIO_Pin_0))
{
Set_gpio(OUT, GPIOF,GPIO_PinSource6);
}
else
{
Reset_gpio(OUT, GPIOF,GPIO_PinSource6);
}
//如果按键2按下，则为低电平，就点亮LED2
if(ReadInput_gpio(GPIOF,GPIO_Pin_2))
{
Set_gpio(OUT, GPIOF,GPIO_PinSource5);
}
else
{
Reset_gpio(OUT, GPIOF,GPIO_PinSource5);
}
//如果按键1按下，则为低电平，就点亮LED1
if(ReadInput_gpio(GPIOG,GPIO_Pin_3))
{
Set_gpio(OUT, GPIOF,GPIO_PinSource4);
}
else
{
Reset_gpio(OUT, GPIOF,GPIO_PinSource4);
}
}
return 0;
}
原理图：
外部电源上拉：
EINT0->对应引脚GPF0
EINT2->对应引脚GPF2
EINT11->对应引脚GPG3
即，默认高电平，按键按下就低电平。
Makefile和之前一样，ok，这样是不是觉得方便多了？当然，这是建立在你熟练运用C语言的基础上的，不然是写不出库函数的。
原文地址：https://www.cnblogs.com/Liu-Jing/p/8206169.html
时间： 2024-10-12 07:06:58