Class: GBRb::InstructionSet::Rl

Inherits:
Instruction show all
Defined in:
lib/gbrb/instruction_set/rotate.rb

Instance Attribute Summary

Attributes inherited from Instruction

#i, #m, #t

Instance Method Summary collapse

Methods inherited from Instruction

#carry?, #immediate_count

Constructor Details

#initialize(target, carry = false, indirect = false, m = 1, t = 4, zero = true) ⇒ Rl

Returns a new instance of Rl.



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# File 'lib/gbrb/instruction_set/rotate.rb', line 6

def initialize target, carry=false, indirect=false, m=1, t=4, zero=true
  super m, t
  @target = target.to_sym
  @carry = carry
  @indirect = indirect
  @zero_check = zero
end

Instance Method Details

#call(r, mem) ⇒ Object 



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# File 'lib/gbrb/instruction_set/rotate.rb', line 14

def call r, mem
  if @indirect
    address = r.public_send(@target).read
    v = mem.read_byte(address) << 1
  else
    v = r.public_send(@target).read << 1
  end

  carry_in = if @carry
               v & 0x100 == 0x100 ? 1 : 0
             else
               r.carry_flag? ? 1 : 0
             end

  v += carry_in

  if @indirect
    mem.write_byte(address, v)
  else
    r.public_send(@target).store v
  end

  r.clear_add_sub_flag
  r.clear_half_carry_flag
  if @zero_check
    v & 0xff == 0 ? r.set_zero_flag : r.clear_zero_flag
  else
    r.clear_zero_flag
  end
  carry_out = v >> 8
  carry_out == 1 ? r.set_carry_flag : r.clear_carry_flag
end