Class: Amaterasu::GameBoy::Cpu::Instructions::Pop

Inherits:
Base
  • Object
show all
Defined in:
lib/amaterasu/game_boy/cpu/instructions/pop.rb,
sig/akane/game_boy/cpu/instructions/pop.rbs

Overview

Holds the logic of all the POP instructions.

Instance Attribute Summary

Attributes inherited from Base

#mnemonic

Instance Method Summary collapse

Methods inherited from Base

#execute, #format_operand

Constructor Details

#initialize(cpu:, reg16:) ⇒ Pop

Creates a Pop instruction object with a mnemonic and logic to be executed.

Parameters:

  • cpu: (Cpu)
  • reg16: (Symbol) 


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# File 'lib/amaterasu/game_boy/cpu/instructions/pop.rb', line 10

def initialize(cpu:, reg16:)
  super(cpu:)

  @mnemonic = "POP #{format_operand(reg16)}"
  @logic    = build_logic(reg16)
end

Instance Method Details

#build_logic(reg16) ⇒ Proc

Returns a Proc object to be executed by the CPU at runtime.

M-cycle 1: Fetches opcode. M-cycle 2: Gets the reg16 lsb from the stack. M-cycle 3: Gets the reg16 msb from the stack. Assigns the 16-bit value to a given reg16 (same cycle).

Parameters:

  • reg16 (Symbol)

Returns:

  • (Proc) 


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# File 'lib/amaterasu/game_boy/cpu/instructions/pop.rb', line 25

def build_logic(reg16)
  case reg16
  when :bc then -> { @registers.bc = @cpu.stack_pop }
  when :de then -> { @registers.de = @cpu.stack_pop }
  when :hl then -> { @registers.hl = @cpu.stack_pop }
  when :af then -> { @registers.af = @cpu.stack_pop }
  else
    raise ArgumentError, 'Unknown Pop reg16'
  end
end