Class: PSX::BIOS

Inherits:
Object
  • Object
show all
Defined in:
lib/psx/bios.rb

Constant Summary collapse

SIZE =

512 KB

512 * 1024

Instance Method Summary collapse

Constructor Details

#initialize(path) ⇒ BIOS

Returns a new instance of BIOS.



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# File 'lib/psx/bios.rb', line 7

def initialize(path)
  @data = File.binread(path)

  if @data.bytesize != SIZE
    raise ArgumentError, "Invalid BIOS size: expected #{SIZE} bytes, got #{@data.bytesize}"
  end

  # Pre-compute 32-bit word array for fast read32 access
  # This trades memory for speed (512KB -> 512KB + 128K integers)
  @words = Array.new(SIZE / 4) do |i|
    offset = i * 4
    @data.getbyte(offset) |
      (@data.getbyte(offset + 1) << 8) |
      (@data.getbyte(offset + 2) << 16) |
      (@data.getbyte(offset + 3) << 24)
  end
end

Instance Method Details

#read16(offset) ⇒ Object 



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# File 'lib/psx/bios.rb', line 29

def read16(offset)
  @data.getbyte(offset) | (@data.getbyte(offset + 1) << 8)
end

#read32(offset) ⇒ Object 



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# File 'lib/psx/bios.rb', line 33

def read32(offset)
  # Fast path: aligned access from pre-computed array
  if (offset & 3) == 0
    @words[offset >> 2]
  else
    # Unaligned access (rare)
    @data.getbyte(offset) |
      (@data.getbyte(offset + 1) << 8) |
      (@data.getbyte(offset + 2) << 16) |
      (@data.getbyte(offset + 3) << 24)
  end
end

#read8(offset) ⇒ Object 



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# File 'lib/psx/bios.rb', line 25

def read8(offset)
  @data.getbyte(offset)
end