output all logical immediate values with n, immr and imms

aarch64-logical-immediates.rb

def get_imms(size, length)
  length | case size
  when  2 then 0b111100
  when  4 then 0b111000
  when  8 then 0b110000
  when 16 then 0b100000
  when 32 then 0b000000
  when 64 then 0b000000
  end
end

def disasm(val)
  content = ".section .text\n.globl _start\n_start:\nand x0, x0, 0x#{val.to_s(16)}\n"
  File.open("disasm.s", "w") do |f|
    f.write(content)
  end

  system("aarch64-linux-gnu-as disasm.s -o disasm.o")
  result = `aarch64-linux-gnu-objdump -d disasm.o`

  for line in result.lines
    cols = line.split

    if cols[0] == "0:"
      return (cols[1].to_i(16) >> 10) & 0x1fff
    end
  end

  raise "line not found"
end

for size in 1..6
  size = 1 << size

  for length in 0...size-1
    result = (1 << (length + 1)) - 1

    e = size

    while e < 64
      result = result | (result << e)
      e = e * 2
    end

    for rotation in 0...size
      n = size == 64 ? 1 : 0
      immr = rotation
      imms = get_imms(size, length)

      value = n << 12 | immr << 6 | imms
      disasm_value = disasm(result)

      if value != disasm_value
        puts "FAIL: %013b != %013b" % [value, disasm_value]
        raise "wrong encoding"
      end

      puts "%016x %064b size=%02d length=%02d rotation=%02d N=%01b immr=%06b imms=%06b" % [result, result, size, length, rotation, n, immr, imms]
      result = (((result & 1) << 63) | (result >> 1)) & 0xFFFFFFFF_FFFFFFFF


    end
  end
end