ARM-第四次

配置环境

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将hello.c下载进开发板

• 不能运行,因为hello.c里面的头文件不适用与u-boot

在u-boot下输入/输出(输出)

1.cd ~/1612/1/sq1612/bootloader/u-boot
2.vi include/common.h(看common里面的函数原型)
3.找到cd ~/1612/1/sq1612/bootloader/u-boot/下的u-boot.map里的pingtf的地址:如下

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4.解决hello.c不能运行的问题

5.在sq1612下创建04的文件夹,进入04,然后mkdir 1_hello ,进入1_hello,vim hello.c

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6.vi Makefile

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7.make好了之后,先检查网络是否连通

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在u-boot下输入

1.找到getc的原型(0x33f965f0)(函数原型:gedit /include/common.h)

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2.新建2_hello 在里面创建hello.c

int (*my_scanf)(void);
void (*my_printf)(const char * fmt,...);

int _start()
{
    int ch;
    my_scanf=(void *)0x33f965f0;
    my_printf=(void *)0x33f963a8;
    while(1)
    {
        ch=my_scanf();
        if(ch=='q')
        {
            break;
        }
        my_printf("%c\n",ch);
    }
    my_printf("lalalalla\n");
    
    return 0;
}

3.新建Makefile

 CC=arm-linux-
    TARGET=hello
    all:
        $(CC)gcc -c $(TARGET).c -o $(TARGET).o
        $(CC)ld -Ttext 0x30000000 $(TARGET).o -o $(TARGET)
        $(CC)objcopy -O binary $(TARGET) $(TARGET).bin
        cp $(TARGET).bin /tftpboot/
    clean:
    rm /tftpboot/$(TARGET).bin *.o *.bin $(TARGET)

4.make一下
5.在下载开始一定要重启一下开发板
6.ping 192.168.0.1
7.tftp 0x30000000 hello.bin
8.go 0x30000000

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9.common.h在u-boot下输入:gedit include/common.h

汇编指令

1.以C的形式实现两书相加

void (*my_printf)(const char* fmt,...);
int  (*my_getc)(void);
int _start(void)
{
    int a,b,c;
    my_printf = (void *)0x33f963a8;
    my_getc   = (void *)0x33f965f0;

    a=my_getc();
    my_printf("%c\n",a);
    a-='0';
    b=my_getc();
    b-='0';
    my_printf("%d\n",b);

    my_printf("%d+%d=%d",a,b,c);
    return 0;
}

2.以汇编语言的形式实现两数相加

void (*my_printf)(const char* fmt,...);
int  (*my_getc)(void);
int _start(void)
{
    int a,b,c;
    my_printf = (void *)0x33f963a8;
    my_getc   = (void *)0x33f965f0;

    a=my_getc();
    my_printf("%c\n",a);
    a-='0';
    b=my_getc();
    b-='0';
    my_printf("%d\n",b);
    
    __asm__ __volatile__
    (
        "mov r0,%1\n"//将a的值放到r0中
        "mov r1,%2\n"//将b的值放到r1中
        "add r2,r0,r1\n"//将r0和r1的值进加放入r2中
        "mov %0,r2\n"//将r2的值赋给c

        :"=r"(c)//r0
        :"r"(a),"r"(b)//a:r1,b:r2
        :"r0","r1","r2"
    )
    my_printf("%d+%d=%d",a,b,c);
    return 0;
}

3.下载到开发板

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4.ldrstr

void (*my_printf)(const char* fmt,...);
int  (*my_getc)(void);
int _start(void)
{
    int a,b;
    my_printf = (void *)0x33f963a8;
    my_getc   = (void *)0x33f965f0;

    a=my_getc();
    my_printf("%c\n",a);
    
    __asm__ __volatile__(
        "mov r1,%1\n"//a存r1
        "ldr r0,=0x30008000\n"//创建一个指针
        "str r1,[r0]\n"//a存入指针
        "ldr r2,[r0]\n"//把指针内容给r2
        "mov %0,r2\n"//把r2放入b

        :"=r"(b)
        :"r"(a)
        :"r0","r1","r2"
    );
    my_printf("%c",b);
    return 0;
}

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5.stmia与ldmstm

void (*my_printf)(const char* fmt,...);
int _start(void)
{
    int a,b,c,d;
    my_printf = (void *)0x33f963a8;

    __asm__ __volatile__(
        "mov r1,#0x01\n"
        "mov r2,#0x02\n"
        "mov r3,#0x03\n"
        "mov r4,#0x04\n"
        "ldr r0,=0x30008000\n"//创建指针    
        "stmia r0!,{r1-r4}\n"//指定r0的变化方式

        "ldr r0,=0x30008000\n"
        "ldmia r0!,{r1-r4}\n"
        "mov %0,r1\n"
        "mov %1,r2\n"
        "mov %2,r3\n"
        "mov %3,r4\n"

        :"=r"(a),"=r"(b),"=r"(c),"=r"(d)
        :
        :"r0","r1","r2","r3","r4"
    );
    my_printf("a=%d,b=%d,c=%d,d=%d",a,b,c,d);
    return 0;
}

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6.ld

int _start(void)
{
    void (*my_printf)(const char* fmt,...);
    my_printf = (void *)0x33f963a8;
    my_printf("In %s: before bl.\n",__func__);
    __asm__ __volatile__(
        "bl mytest\n"
    );
    my_printf("In %s: after bl.\n",__func__);
    return 0;
}
void mytest()
{
    void (*my_printf)(const char* fmt,...);
    my_printf = (void *)0x33f963a8;
    
    my_printf("In %s:in bl.\n",__func__);
}

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7.条件代码(两个数进行比较)(大的那个数进行+1)

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