brainf**k compiler for 32bit X86 Linux

bf2asm.rb

puts DATA.read

labelnum = 0
labelstack = []
ARGF.each_char do |c|
  puts "  # #{c}"
  case c
  when '>'
    puts '  addl $4, %eax'
  when '<'
    puts '  addl $-4, %eax'
  when '+'
    puts '  addl $1, (%eax)'
  when '-'
    puts '  addl $-1, (%eax)'
  when '['
    labelbegin, labelend = [labelnum += 1, labelnum += 1]
    labelstack.push([labelbegin, labelend])
    puts "L#{labelbegin}:"
    puts '  cmp $0, (%eax)'
    puts "  jz L#{labelend}"
  when ']'
    labelbegin, labelend = labelstack.pop
    puts "  jmp L#{labelbegin}"
    puts "L#{labelend}:"
  when '.'
    puts "  pushl %eax"
    puts "  pushl (%eax)"
    puts "  call putchar"
    puts "  popl %eax # just to throw it away"
    puts "  popl %eax"
  when ','
    puts "  pushl %eax"
    puts "  call getchar"
    puts "  movl %eax, %ecx"
    puts "  popl %eax"
    puts "  movl %ecx, (%eax)"
  else
    # nop
  end
end
puts "  movl $0, %eax"
puts "  leave"
puts "  ret"

__END__
  .text
.globl main
  .type main, @function
main:
  pushl %ebp
  movl %esp, %ebp
  subl $4, %esp
  movl $0, (%esp)
  subl $4, %esp
  movl $0, (%esp)
  subl $4, %esp
  movl $0, (%esp)
  subl $4, %esp
  movl $0, (%esp)
  subl $4, %esp
  movl $0, (%esp)
  subl $4, %esp
  movl $0, (%esp)
  subl $4, %esp
  movl $0, (%esp)
  subl $4, %esp
  movl $0, (%esp)
  subl $4, %esp
  movl $0, (%esp)
  subl $4, %esp
  movl $0, (%esp)
  subl $4, %esp
  movl $0, (%esp)
  subl $4, %esp
  movl $0, (%esp)
  movl %esp, %eax

how to run

$ ruby bf2asm.rb ./helloworld.bf > hello.s
$ as --32 hello.s -o a.o && ld -m elf_i386 -dynamic-linker /lib32/ld-linux.so.2 /usr/lib32/crt1.o /usr/lib32/crti.o -lc /usr/lib32/crtn.o a.o -o ./a && ./a


Hello World!