bootloader.c

原创作品

/*
 *bootloader.c
 *
 *
 *Loads an ELF kernel from flash memory.
 *
 *auther:hegs
 *
 *mail:[e-mail] 
 */

#include "bootloader.h" 
void main(void)
{
	static char *mem = (char *)FLASH_MEM0_BASEADDR;

	Elf32_Ehdr *elf;        //elf file header
	Elf32_Phdr *elf_phdr;	/* program segment header */
	unsigned long e_entry,  
	              e_phoff,  //program head offset (at file)
	              e_phnum;  //phdr number
	              
  int i;
    
  while(1)
  {
	 elf = (Elf32_Ehdr *) mem;
	
	 if (elf->e_ident[0] !=0x7f ||  
	    elf->e_ident[1] !='E' ||
	    elf->e_ident[2] !='L' ||
	    elf->e_ident[3] !='F' )
	 {
		print("not an ELF file\n");
		continue; //??flash ??
	}
	if (elf->e_type != ET_EXEC) {
		print("not an ELF executable\n");
		continue;
	}

	e_entry = elf->e_entry;
	e_phnum = elf->e_phnum;
	e_phoff = elf->e_phoff;


	for (i = 0; i < e_phnum; ++i)
	{
		elf_phdr = (Elf32_Phdr *) (e_phoff+mem);
		
		e_phoff += sizeof(*elf_phdr);

		if (elf_phdr->p_type != PT_LOAD)
			continue;

		memcpy((void *)(elf_phdr->p_vaddr), (void*)(elf_phdr->p_offset+mem), elf_phdr->p_filesz);
		memset((char*)(elf_phdr->p_vaddr+elf_phdr->p_filesz), 0, elf_phdr->p_memsz - elf_phdr->p_filesz);
	}

	print("starting kernel...\n");

	void (*boot)();
	boot=(void*)e_entry;  
	boot();
	//???????????
	#ifdef LED_BASEADDR
	XIo_Out32(LED_BASEADDR, 0x55);
	XIo_Out32(LED_BASEADDR, 0xaa);
	#endif
 }
}