Class: PSX::Memory

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

Constant Summary collapse

RAM_START =

Memory regions (physical addresses)

0x0000_0000
RAM_SIZE =

2 MB (mirrored 4x in 8 MB region)

0x0020_0000
RAM_MIRROR_MASK = 
0x001F_FFFF
SCRATCHPAD_START = 
0x1F80_0000
SCRATCHPAD_SIZE =

1 KB

0x0000_0400
IO_START = 
0x1F80_1000
IO_SIZE = 
0x0000_2000
BIOS_START = 
0x1FC0_0000
BIOS_SIZE =

512 KB

0x0008_0000
REGION_MASK =

Region masks for KSEG translation

[
  0xFFFF_FFFF, 0xFFFF_FFFF, 0xFFFF_FFFF, 0xFFFF_FFFF,  # KUSEG: 0x0000_0000 - 0x7FFF_FFFF
  0x7FFF_FFFF,                                          # KSEG0: 0x8000_0000 - 0x9FFF_FFFF (cached)
  0x1FFF_FFFF,                                          # KSEG1: 0xA000_0000 - 0xBFFF_FFFF (uncached)
  0xFFFF_FFFF, 0xFFFF_FFFF                              # KSEG2: 0xC000_0000 - 0xFFFF_FFFF
].freeze

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(bios:, ram:, interrupts: nil, dma: nil, timers: nil, cdrom: nil, sio0: nil, spu: nil) ⇒ Memory

Returns a new instance of Memory.



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

def initialize(bios:, ram:, interrupts: nil, dma: nil, timers: nil, cdrom: nil, sio0: nil, spu: nil)
  @bios = bios
  @ram = ram
  @interrupts = interrupts
  @dma = dma
  @timers = timers
  @cdrom = cdrom
  @sio0 = sio0
  @spu = spu
  @gpu = nil  # Set later when GPU is created
  @scratchpad = ("\x00" * SCRATCHPAD_SIZE).b  # Force binary encoding
  @cache_isolated = false
end

Instance Attribute Details

#cache_isolated ⇒ Object

Returns the value of attribute cache_isolated.



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# File 'lib/psx/memory.rb', line 27

def cache_isolated
  @cache_isolated
end

#cdrom ⇒ Object

Returns the value of attribute cdrom.



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# File 'lib/psx/memory.rb', line 27

def cdrom
  @cdrom
end

#dma ⇒ Object

Returns the value of attribute dma.



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# File 'lib/psx/memory.rb', line 27

def dma
  @dma
end

#gpu ⇒ Object

Returns the value of attribute gpu.



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# File 'lib/psx/memory.rb', line 27

def gpu
  @gpu
end

#sio0 ⇒ Object

Returns the value of attribute sio0.



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# File 'lib/psx/memory.rb', line 27

def sio0
  @sio0
end

#spu ⇒ Object

Returns the value of attribute spu.



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# File 'lib/psx/memory.rb', line 27

def spu
  @spu
end

Instance Method Details

#read16(addr) ⇒ Object 



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# File 'lib/psx/memory.rb', line 71

def read16(addr)
  phys = addr & REGION_MASK[(addr >> 29) & 0x7]

  # RAM (most common)
  return @ram.read16(phys & RAM_MIRROR_MASK) if phys < 0x0080_0000

  # BIOS
  return @bios.read16(phys - BIOS_START) if phys >= 0x1FC0_0000 && phys < 0x1FC8_0000

  # Scratchpad
  if phys >= 0x1F80_0000 && phys < 0x1F80_0400
    offset = phys - SCRATCHPAD_START
    return @scratchpad.getbyte(offset) | (@scratchpad.getbyte(offset + 1) << 8)
  end

  # I/O
  return io_read16(phys - IO_START) if phys >= 0x1F80_1000 && phys < 0x1F80_3000

  0
end

#read32(addr) ⇒ Object 



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# File 'lib/psx/memory.rb', line 92

def read32(addr)
  # Fast path: translate virtual to physical
  phys = addr & REGION_MASK[(addr >> 29) & 0x7]

  # Fast path for RAM (most common case)
  if phys < 0x0080_0000
    return @ram.read32(phys & RAM_MIRROR_MASK)
  end

  # Fast path for BIOS
  if phys >= 0x1FC0_0000 && phys < 0x1FC8_0000
    return @bios.read32(phys - BIOS_START)
  end

  # Scratchpad
  if phys >= 0x1F80_0000 && phys < 0x1F80_0400
    offset = phys - SCRATCHPAD_START
    return @scratchpad.getbyte(offset) |
           (@scratchpad.getbyte(offset + 1) << 8) |
           (@scratchpad.getbyte(offset + 2) << 16) |
           (@scratchpad.getbyte(offset + 3) << 24)
  end

  # I/O
  return io_read32(phys - IO_START) if phys >= 0x1F80_1000 && phys < 0x1F80_3000

  # Cache control
  return 0 if phys >= 0xFFFE_0000 && phys < 0xFFFE_0200

  # Expansion regions
  return 0xFFFF_FFFF if phys >= 0x1F00_0000 && phys < 0x1F80_0000
  return 0xFFFF_FFFF if phys >= 0x1F80_2000 && phys < 0x1F80_2100

  0
end

#read8(addr) ⇒ Object 



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# File 'lib/psx/memory.rb', line 47

def read8(addr)
  phys = addr & REGION_MASK[(addr >> 29) & 0x7]

  # RAM (most common)
  return @ram.read8(phys & RAM_MIRROR_MASK) if phys < 0x0080_0000

  # BIOS
  return @bios.read8(phys - BIOS_START) if phys >= 0x1FC0_0000 && phys < 0x1FC8_0000

  # Scratchpad
  if phys >= 0x1F80_0000 && phys < 0x1F80_0400
    return @scratchpad.getbyte(phys - SCRATCHPAD_START)
  end

  # I/O
  return io_read8(phys - IO_START) if phys >= 0x1F80_1000 && phys < 0x1F80_3000

  # Expansion regions
  return 0xFF if phys >= 0x1F00_0000 && phys < 0x1F80_0000
  return 0xFF if phys >= 0x1F80_2000 && phys < 0x1F80_2100

  0
end

#tick_dma ⇒ Object 



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# File 'lib/psx/memory.rb', line 43

def tick_dma
  @dma&.tick(self, gpu: @gpu)
end

#write16(addr, value) ⇒ Object 



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# File 'lib/psx/memory.rb', line 155

def write16(addr, value)
  return if @cache_isolated

  phys = addr & REGION_MASK[(addr >> 29) & 0x7]

  # RAM (most common)
  if phys < 0x0080_0000
    @ram.write16(phys & RAM_MIRROR_MASK, value)
    return
  end

  # Scratchpad
  if phys >= 0x1F80_0000 && phys < 0x1F80_0400
    offset = phys - SCRATCHPAD_START
    @scratchpad.setbyte(offset, value & 0xFF)
    @scratchpad.setbyte(offset + 1, (value >> 8) & 0xFF)
    return
  end

  # I/O
  if phys >= 0x1F80_1000 && phys < 0x1F80_3000
    io_write16(phys - IO_START, value)
    return
  end

  # BIOS (read-only)
  warn format("Write to BIOS at 0x%08X", addr) if phys >= 0x1FC0_0000 && phys < 0x1FC8_0000
end

#write32(addr, value) ⇒ Object 



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# File 'lib/psx/memory.rb', line 184

def write32(addr, value)
  return if @cache_isolated

  # Fast path: translate virtual to physical
  phys = addr & REGION_MASK[(addr >> 29) & 0x7]

  # Fast path for RAM (most common case)
  if phys < 0x0080_0000
    @ram.write32(phys & RAM_MIRROR_MASK, value)
    return
  end

  # Scratchpad
  if phys >= 0x1F80_0000 && phys < 0x1F80_0400
    offset = phys - SCRATCHPAD_START
    @scratchpad.setbyte(offset, value & 0xFF)
    @scratchpad.setbyte(offset + 1, (value >> 8) & 0xFF)
    @scratchpad.setbyte(offset + 2, (value >> 16) & 0xFF)
    @scratchpad.setbyte(offset + 3, (value >> 24) & 0xFF)
    return
  end

  # I/O
  if phys >= 0x1F80_1000 && phys < 0x1F80_3000
    io_write32(phys - IO_START, value)
    return
  end

  # BIOS (read-only)
  if phys >= 0x1FC0_0000 && phys < 0x1FC8_0000
    warn format("Write to BIOS at 0x%08X", addr)
    return
  end

  # Cache control and expansion regions - ignore writes
end

#write8(addr, value) ⇒ Object 



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# File 'lib/psx/memory.rb', line 128

def write8(addr, value)
  return if @cache_isolated  # Writes go to cache, not memory

  phys = addr & REGION_MASK[(addr >> 29) & 0x7]

  # RAM (most common)
  if phys < 0x0080_0000
    @ram.write8(phys & RAM_MIRROR_MASK, value)
    return
  end

  # Scratchpad
  if phys >= 0x1F80_0000 && phys < 0x1F80_0400
    @scratchpad.setbyte(phys - SCRATCHPAD_START, value & 0xFF)
    return
  end

  # I/O
  if phys >= 0x1F80_1000 && phys < 0x1F80_3000
    io_write8(phys - IO_START, value)
    return
  end

  # BIOS (read-only)
  warn format("Write to BIOS at 0x%08X", addr) if phys >= 0x1FC0_0000 && phys < 0x1FC8_0000
end