dump a.out

dump-aout.groovy

// http://www.iecc.com/linker/linker03.html
// Figure 2: a.out header 

// int a_magic;  -- magic number 
// int a_text;   -- text segment size 
// int a_data;   -- initialized data size 
// int a_bss;    -- uninitialized data size 
// int a_syms;   -- symbol table size 
// int a_entry;  -- entry point 
// int a_trsize; -- text relocation size 
// int a_drsize; -- data relocation size

aout = new Aout()
headerSize = 16


def printDump(List hexStrs, int pc) {
  if(hexStrs[pc] == "15" && hexStrs[pc+1] == "C0") {
    // MOV
    println Integer.toHexString(pc) + ": 15c0 " + hexStrs[pc+2] + hexStrs[pc+3] + " mov \$" + Integer.parseInt(hexStrs[pc+3], 16) + ", r" + Integer.parseInt(hexStrs[pc+2], 16)
    return pc + 4
  }
  if(hexStrs[pc] == "89") {
    // SYS
    println Integer.toHexString(pc) + ": 89" + hexStrs[pc+1] + "      sys " + Integer.parseInt(hexStrs[pc+1], 16)
    return pc + 2
  }
  if(hexStrs[pc] == "00" && hexStrs[pc+1] == "10") {
    // .WORD
    println Integer.toHexString(pc) + ": 0010      .word 20" 
    return pc + 2
  }
  if(hexStrs[pc] == "00" && hexStrs[pc+1] == "06") {
    // RTT
    println Integer.toHexString(pc) + ": 0006      rtt" 
    return pc + 2
  }
}

def dump = { prog -> 
  bytes = []
  String tmp = ""
  prog.toList().eachWithIndex { str, idx ->
    tmp += str
    if((idx + 1) % 2 == 0) {
      bytes += tmp
      tmp = ""
    }
  } 
  int nextPc = 0
  bytes.eachWithIndex { b, pc -> 
    if(pc == nextPc) {
      nextPc = printDump(bytes, pc)
    }
  }
}

def analyze = {
  InputStream input = new BufferedInputStream(new FileInputStream(new File('a.out')));
  int counter = 0
  String tmp = ""
  while ((c = input.read()) != -1) {
    String hex = Integer.toHexString(c).toUpperCase().padLeft(2, "0")

    // a_text
    if(counter == 2 || counter == 3) {
      aout.header.atext = hex + aout.header.atext
    }
    // a_data
    if(counter == 4 || counter == 5) {
      aout.header.adata = hex + aout.header.adata
    }

    // program
    if(counter >= headerSize) {
      def pc = headerSize + aout.header.atextAsInt()
      if(counter < pc){
        if(counter % 2 == 1) {
          tmp = hex + tmp
          aout.program += tmp
        } else {
          tmp = hex
        }
      }
    }
    counter++
  }
}

class Aout {
  Header header = new Header()
  String program = ""
  String data = ""
}

class Header {
  String atext = ""
  String adata = ""
  def atextAsInt(){ 
    (this.atext != "") ? Integer.parseInt(this.atext, 16) : 0
  }
  def adataAsInt(){
    (this.adata != "") ? Integer.parseInt(this.adata, 16) : 0
  }
}

analyze()
dump(aout.program)