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//convert.c by Steve Rhoads 4/26/01
//Now uses the ELF format (get gccmips_elf.zip) 
//set $gp and zero .sbss and .bss
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
#define BUF_SIZE (1024*1024)
/*Assumes running on PC little endian*/
#define ntohl(A) (((A)>>24)|(((A)&0x00ff0000)>>8)|(((A)&0xff00)<<8)|((A)<<24))
#define ntohs(A) ((((A)&0xff00)>>8)|((A)<<8))
 
#define EI_NIDENT 16
#define SHT_PROGBITS 1
#define SHT_STRTAB 3
#define SHT_NOBITS 8
 
typedef struct {
   unsigned char  e_ident[EI_NIDENT];
   unsigned short e_e_type;
   unsigned short e_machine;
   unsigned long  e_version;
   unsigned long  e_entry;
   unsigned long  e_phoff;
   unsigned long  e_shoff;
   unsigned long  e_flags;
   unsigned short e_ehsize;
   unsigned short e_phentsize;
   unsigned short e_phnum;
   unsigned short e_shentsize;
   unsigned short e_shnum;
   unsigned short e_shstrndx;
} ElfHeader;
 
typedef struct {
   unsigned long p_type;
   unsigned long p_offset;
   unsigned long p_vaddr;
   unsigned long p_paddr;
   unsigned long p_filesz;
   unsigned long p_memsz;
   unsigned long p_flags;
   unsigned long p_align;
} Elf32_Phdr;
 
typedef struct {
   unsigned long sh_name;
   unsigned long sh_type;
   unsigned long sh_flags;
   unsigned long sh_addr;
   unsigned long sh_offset;
   unsigned long sh_size;
   unsigned long sh_link;
   unsigned long sh_info;
   unsigned long sh_addralign;
   unsigned long sh_entsize;
} Elf32_Shdr;
 
#if 0
unsigned long load(unsigned char *ptr,unsigned long address)
{
   unsigned long value;
   value=*(unsigned long*)(ptr+address);
   value=ntohl(value);
   return value;
}
 
unsigned short load_short(unsigned char *ptr,unsigned long address)
{
   return (ptr[address]<<8)+ptr[address+1];
}
#endif
 
void set_low(char *ptr,unsigned long address,unsigned long value)
{
   unsigned long opcode;
   opcode=*(unsigned long*)(ptr+address);
   opcode=ntohl(opcode);
   opcode=(opcode&0xffff0000)|(value&0xffff);
   opcode=ntohl(opcode);
   *(unsigned long*)(ptr+address)=opcode;
}
 
int main(int argc,char *argv[])
{
   FILE *infile,*outfile,*txtfile;
   unsigned char *buf,*code;
   long size,stack_pointer;
   unsigned long length,d,i,gp_ptr=0;
   unsigned long bss_start=0,bss_end=0;
 
   ElfHeader *elfHeader;
   Elf32_Phdr *elfProgram;
   Elf32_Shdr *elfSection;
 
   printf("test.exe -> code.txt & test2.exe\n");
   infile=fopen("test.exe","rb");
   if(infile==NULL) {
      printf("Can't open test.exe");
      return 0;
   }
   buf=(unsigned char*)malloc(BUF_SIZE);
   size=fread(buf,1,BUF_SIZE,infile);
   fclose(infile);
   code=(unsigned char*)malloc(BUF_SIZE);
   memset(code,0,BUF_SIZE);
 
   elfHeader=(ElfHeader*)buf;
   if(strncmp(elfHeader->e_ident+1,"ELF",3)) {
      printf("Error:  Not an ELF file!\n");
      printf("Use the gccmips_elf.zip from opencores/projects/plasma!\n");
      return -1;
   }
 
   elfHeader->e_entry=ntohl(elfHeader->e_entry);
   elfHeader->e_phoff=ntohl(elfHeader->e_phoff);
   elfHeader->e_shoff=ntohl(elfHeader->e_shoff);
   elfHeader->e_phentsize=ntohs(elfHeader->e_phentsize);
   elfHeader->e_phnum=ntohs(elfHeader->e_phnum);
   elfHeader->e_shentsize=ntohs(elfHeader->e_shentsize);
   elfHeader->e_shnum=ntohs(elfHeader->e_shnum);
   length=0;
 
   for(i=0;i<elfHeader->e_phnum;++i) {
      elfProgram=(Elf32_Phdr*)(buf+elfHeader->e_phoff+elfHeader->e_phentsize*i);
      elfProgram->p_offset=ntohl(elfProgram->p_offset);
      elfProgram->p_vaddr=ntohl(elfProgram->p_vaddr);
      elfProgram->p_filesz=ntohl(elfProgram->p_filesz);
      elfProgram->p_memsz=ntohl(elfProgram->p_memsz);
//      printf("[0x%x,0x%x,0x%x]\n",elfProgram->p_vaddr,elfProgram->p_offset,elfProgram->p_filesz);
      memcpy(code+elfProgram->p_vaddr,buf+elfProgram->p_offset,elfProgram->p_filesz);
      length=elfProgram->p_vaddr+elfProgram->p_memsz;
   }
 
   for(i=0;i<elfHeader->e_shnum;++i) {
      elfSection=(Elf32_Shdr*)(buf+elfHeader->e_shoff+elfHeader->e_shentsize*i);
      elfSection->sh_name=ntohl(elfSection->sh_name);
      elfSection->sh_type=ntohl(elfSection->sh_type);
      elfSection->sh_addr=ntohl(elfSection->sh_addr);
      elfSection->sh_offset=ntohl(elfSection->sh_offset);
      elfSection->sh_size=ntohl(elfSection->sh_size);
#if 0
      printf("{0x%x,0x%x:0x%x,0x%x,0x%x}\n",
         elfSection->sh_name,elfSection->sh_type,elfSection->sh_addr,
         elfSection->sh_offset,elfSection->sh_size);
#endif
#if 0
      if(elfSection->sh_type==SHT_PROGBITS||elfSection->sh_type==SHT_STRTAB) {
//         memcpy(code+elfSection->sh_addr,buf+elfSection->sh_offset,elfSection->sh_size);
         length=elfSection->sh_addr+elfSection->sh_size;
         bss_start=length;
      }
#endif
      if(elfSection->sh_type==SHT_PROGBITS) {
         gp_ptr=elfSection->sh_addr;
      }
      if(elfSection->sh_type==SHT_NOBITS) {
         if(bss_start==0) {
            bss_start=elfSection->sh_addr;
         }
         bss_end=elfSection->sh_addr+elfSection->sh_size;
      }
   }
 
   if(bss_start==length) {
      bss_start=length;
      bss_end=length+4;
   }
 
   /*Initialize the $gp register for sdata and sbss*/   
   gp_ptr+=0x7ff0;
   printf("gp_ptr=0x%x ",gp_ptr);
   /*modify the first opcodes in boot.asm*/
   /*modify the lui opcode*/
   set_low(code,0,gp_ptr>>16);
   /*modify the ori opcode*/
   set_low(code,4,gp_ptr&0xffff);
 
   /*Clear .sbss and .bss*/
   printf(".sbss=0x%x .bss_end=0x%x\n",bss_start,bss_end);
   set_low(code,8,bss_start);
   set_low(code,12,bss_end);
 
   /*Set stack pointer*/
   stack_pointer=bss_end+512;
   printf("Stack pointer=0x%x\n",stack_pointer);
   set_low(code,16,stack_pointer);
 
   /*write out code.txt*/
   outfile=fopen("test2.exe","wb");
   fwrite(code,length,1,outfile);
   fclose(outfile);
 
   txtfile=fopen("code.txt","w");
   for(i=0;i<=length;i+=4) {
      d=ntohl(*(unsigned long*)(code+i));
      fprintf(txtfile,"%8.8x\n",d);
   }
   fclose(txtfile);
   free(buf);
 
   return 0;
}