基于UBOOT的应用程序的研究-UART

平台

cpu: s3c2410;
板子: SMDK2410;

---

head.s

.text
.global _start
_start:
   ldr r0,=0x56000010
   mov r1,#0x0
   str r1,[r0] 
   ldr sp,=1024*4
   bl main
halt_loop:
   b halt_loop

---

main.c

int main()
{
    unsigned char c;
    uart0_init();   
    c = 'a';

   while(1)
   {
 	c = getc_dancy();
 	if (isDigit(c) || isLetter(c))
 	putc_dancy(c++);
        return 0;
}

void uart0_init(void)
{
    GPHCON  |= 0xa0; 
    GPHUP   = 0x0c;
    ULCON0  = 0x03; 
    UCON0   = 0x05; 
    UFCON0  = 0x00; 
    UMCON0  = 0x00; 
    UBRDIV0 = UART_BRD;
}

void putc_dancy(unsigned char c)
{
    while (!(UTRSTAT0 & TXD0READY));
    UTXH0 = c;
}
unsigned char getc_dancy(void)
{
    while (!(UTRSTAT0 & RXD0READY));
    return URXH0;
}

int isDigit(unsigned char c)
{
    if (c >= '0' && c <= '9')
        return 1;
    else
        return 0;       
}
int isLetter(unsigned char c)
{
    if (c >= 'a' && c <= 'z')
        return 1;
    else if (c >= 'A' && c <= 'Z')
        return 1;       
    else
        return 0;
}

---

Makefile

uart.bin: head.S main.c
	arm-linux-gcc -g -c -o head.o head.S
 	arm-linux-gcc -g -c -o main.o main.c
#	arm-linux-ld -Ttext 0x30008000 -g head.o main.o -o uart
	arm-linux-ld -Tuart.lds -o uart head.o main.o
	arm-linux-objcopy -O binary -S uart uart.bin
#	arm-linux-objdump -D -m arm uart > uart.dis

clean: 
 	rm -f uart.bin uart_elf *.o uart

---

uart.lds

SECTIONS {
    . = 0x30008000;
    .text          :   { *(.text) }
    .rodata ALIGN(4) : {*(.rodata)} 
    .data ALIGN(4) : { *(.data) }
    .bss ALIGN(4)  : { *(.bss)  *(COMMON) }
}