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ppu.py
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ppu.py
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"""
Author: Henry-Sky <https://github.com/Henry-Sky>
Date: 2024-06-24
"""
from cartridge import Cartridge
from sprite import Sprite
from utils import TILE, MIRROR, Pixel, PalInit
class Ppu2c02:
def __init__(self):
self.__scanline = 0
self.__cycle = 0
self.odd_frame = False
self.__cart = None
self.nmi = False
self.scanline_trigger = False
self.frame_complete = False
# Internal communications
self.ppu_data_buffer = 0x00
self.address_latch = 0x00
self.fine_x = 0
self.vram_addr = 0x0000 # active "pointer" address into nametable to extract background tile info
"""vram_addr: 16 bit
| Low
| 5 bit : coarse_x
| 5 bit : coarse_y
| 1 bit : nametable_x
| 1 bit : nametable_y
| 3 bit : fine_y
| 1 bit : unused
| High
"""
self.tram_addr = 0x0000 # temporary store of information to be "transferred" into "pointer" at various times
"""tram_addr: 16 bit
| Low
| 5 bit : coarse_x
| 5 bit : coarse_y
| 1 bit : nametable_x
| 1 bit : nametable_y
| 3 bit : fine_y
| 1 bit : unused
| High
"""
# 8 Registers for cpu[$2000~$2007]
self.__control = 0b00000000
"""control
| Low
| 1 bit : nametable_x
| 1 bit : nametable_y
| 1 bit : increment_mode
| 1 bit : pattern_sprite
| 1 bit : pattern_background
| 1 bit : sprite_size
| 1 bit : slave_mode
| 1 bit : enable_nmi
| high
"""
self.__mask = 0b00000000
"""mask
| Low
| 1 bit : grayscale
| 1 bit : render_background_left
| 1 bit : render_sprites_left
| 1 bit : render_background
| 1 bit : render_sprites
| 1 bit : enhance_red
| 1 bit : enhance_green
| 1 bit : enhance_blue
| high
"""
self.__status = 0b00000000
"""status
| Low
| 5 bit : unused
| 1 bit : sprite_overflow
| 1 bit : sprite_zero_hit
| 1 bit : vertical_blank
| high
"""
self.palScreen = PalInit()
self.sprScreen = Sprite(256, 240)
self.sprNameTable = [Sprite(256, 240)] * 2
self.sprPatternTable = [Sprite(128, 128)] * 2
# 2KB = 2 * (960B[NameTable] + 64B[AttributeTable])
self.__tblName = [[0] * 1024] * 2
# 8KB = 2 * 4KB[PatternTable]
self.__tblPattern = [[0] * 4096] * 2
# Colour Rom
self.__tblPalette = [0] * 32
# Background rendering
self.bg_next_tile_id = 0x00
self.bg_next_tile_attrib = 0x00
self.bg_next_tile_lsb = 0x00
self.bg_next_tile_msb = 0x00
self.bg_shifter_pattern_lo = 0x0000
self.bg_shifter_pattern_hi = 0x0000
self.bg_shifter_attrib_lo = 0x0000
self.bg_shifter_attrib_hi = 0x0000
# Foreground rendering
self.oam_addr = 0x00
self.OAM = [TILE(0x00, 0x00, 0x00, 0x00)] * 64
self.sprite_count = 0
self.spriteScanline = [TILE(0, 0, 0, 0)] * 8
self.sprite_shifter_pattern_lo = [0b0] * 8
self.sprite_shifter_pattern_hi = [0b0] * 8
self.bSpriteZEroHitPossible = False
self.bSpriteZeroBeingRendered = False
def GetScreen(self):
return self.sprScreen
def GetNameTable(self, i: int):
return self.sprNameTable[i]
def GetPatternTable(self, i: int, palette: int):
"""
This function draw the CHR ROM for a given pattern table into a Sprite.
Pattern tables consist os 16 x 16 "tiles or characters"
A tile consist of 8 x 8 pixels
On NES pixel are 2 bits witch gives 4 different colours of specific palette
There are 8 palettes to choose from
Characters on NES
~~~~~~~~~~~~~~~~~
The NES stores characters using 2-bit pixels. These are not stored sequentially
but in singular bit planes. For example:
2-Bit Pixels LSB Bit Plane MSB Bit Plane
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 0 0 0 0 0 0 0
0 1 2 0 0 2 1 0 0 1 1 0 0 1 1 0 0 0 1 0 0 1 0 0
0 0 0 0 0 0 0 0 = 0 0 0 0 0 0 0 0 + 0 0 0 0 0 0 0 0
0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 0 0 0 0 0 0 0
0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 0 0 0 0 0 0
0 0 0 2 2 0 0 0 0 0 0 1 1 0 0 0 0 0 0 1 1 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
The planes are stored as 8 bytes of LSB, followed by 8 bytes of MSB
"""
for y in range(16):
for x in range(16):
nOffset = y * 256 + x * 16
for row in range(8):
tile_lsb = self.ppuRead(i * 0x1000 + nOffset + row + 0x0000)
tile_msb = self.ppuRead(i * 0x1000 + nOffset + row + 0x0008)
for col in range(8):
pixel = (tile_lsb & 0x01) + (tile_msb & 0x01)
tile_lsb >>= 1
tile_msb >>= 1
self.sprPatternTable[i].SetPixel(
x=(x * 8) + (7 - col),
y=(y * 8) + row,
p=self.GetColourFromPaletteRam(palette, pixel)
)
# Finally return the updated sprite representing the pattern table
return self.sprPatternTable[i]
def GetColourFromPaletteRam(self, palette: int, pixel: int) -> Pixel:
"""
Taking a specified palette and pixel index
Return the appropriate screen colour
"""
return self.palScreen[self.ppuRead(0x3F00 + (palette << 2) + pixel) & 0x3F]
def connectCart(self, cart: Cartridge):
self.__cart = cart
def reset(self):
self.fine_x = 0x00
self.address_latch = 0x00
self.ppu_data_buffer = 0x00
self.__scanline = 0
self.__cycle = 0
self.bg_next_tile_id = 0x00
self.bg_next_tile_attrib = 0x00
self.bg_next_tile_lsb = 0x00
self.bg_next_tile_msb = 0x00
self.bg_shifter_pattern_lo = 0x0000
self.bg_shifter_pattern_hi = 0x0000
self.bg_shifter_attrib_lo = 0x0000
self.bg_shifter_attrib_hi = 0x0000
self.__status = 0x00
self.vram_addr = 0x0000
self.tram_addr = 0x0000
def cpuWrite(self, addr: int, data: int):
if addr == 0x0000: # Control
self.__control = data
self.tram_addr = (self.tram_addr & 0xC0) | (self.__control & 0x3F)
elif addr == 0x0001: # Mask
self.__mask = data
elif addr == 0x0002: # Status: Not readable
pass
elif addr == 0x0003: # OAM Address: Not readable
pass
elif addr == 0x0004: # OAM Data
tx = data & 0xFF_00_00_00 >> 24
ta = data & 0x00_FF_00_00 >> 16
ti = data & 0x00_00_FF_00 >> 8
ty = data & 0x00_00_00_FF >> 0
self.OAM[self.oam_addr] = TILE(ty, ti, ta, tx)
elif addr == 0x0005: # Scroll
if self.address_latch == 0:
self.fine_x = data & 0x0007
# tram_addr->coarse_x = data >> 3
self.tram_addr = (self.tram_addr & 0x07FF) | ((data >> 3) << 11)
self.address_latch = 1
else:
# tram_addr->fine_y = data & 0x07
self.tram_addr = (self.tram_addr & 0xFFF1) | (data & 0x07 << 1)
# tram_addr->coarse_y = data >> 3
self.tram_addr = (self.tram_addr & 0xF83F) | ((data >> 3) << 6)
self.address_latch = 0
elif addr == 0x0006:
if self.address_latch == 0:
self.tram_addr = ((data & 0x3F) << 8) | (self.tram_addr & 0x00FF)
self.address_latch = 1
else:
self.tram_addr = (self.tram_addr & 0xFF00) | data
self.vram_addr = self.tram_addr
self.address_latch = 0
elif addr == 0x0007:
self.ppuWrite(self.vram_addr, data)
self.vram_addr += 32 if self.__control >= (1 << 5) else 1
else:
pass
def cpuRead(self, addr: int, readonly: bool) -> int:
"""
:param addr: The cpu readable address: $0x0000 ~ $0x0007
:param readonly: If true do read without changing, only in debug mode
:return: The data of ppu data buffer
"""
data = 0x00
if readonly:
"""
Reading behavior could affect the ppu contents，
Hence it，we set the readonly option
The option is used for reading without changing its status
This is really only used for debug mode !
"""
if addr == 0x0000: # Control
data = self.__control
elif addr == 0x0001: # Mask
data = self.__mask
elif addr == 0x0002: # Status
data = self.__status
elif addr == 0x0003: # OAM Address
pass
elif addr == 0x0004: # OAM Data
pass
elif addr == 0x0005: # Scroll
pass
elif addr == 0x0006: # PPU Address
pass
elif addr == 0x0007: # PPU Data
pass
else:
"""
Note that not all registers are capable of being reading
So they just return 0x00
"""
if addr == 0x0000:
# Control : Not readable
pass
elif addr == 0x0001:
# Mask : Not readable
pass
elif addr == 0x0002:
"""
Only the top three bits contain status information
Some game may use the bottom 5 bits "noise" as valid data
"""
data = self.__status & 0xE0 | (self.ppu_data_buffer & 0x1F)
# Clear the vertical blanking flag
self.__status &= 0x7F
self.address_latch = 0
elif addr == 0x0003:
pass
elif addr == 0x0004:
data = self.OAM[self.oam_addr]
elif addr == 0x0005:
pass
elif addr == 0x0006:
pass
elif addr == 0x0007:
data = self.ppu_data_buffer
self.ppu_data_buffer = self.ppuRead(self.vram_addr)
if self.vram_addr >= 0x3F00:
data = self.ppu_data_buffer
self.vram_addr += 32 if self.__control >= (1 << 5) else 1
else:
pass
return data
def ppuRead(self, addr: int, readonly=False) -> int:
"""
1. Get address to PPU range
2. Judge ppu address
case 0x0000-0x1FFF : Pattern Tables
case 0x2000-0x2FFF : Name Tables
case 0x3000-0x3EFF : Mirrors
case 0x3F00-0x3F1F : Palette RAM
case 0x3F20-0x3FFF : Mirrors
"""
addr &= 0x3FFF
flag, data = self.__cart.ppuRead(addr)
if flag:
pass
elif 0x0000 <= addr <= 0x1FFF:
data = self.__tblPattern[(addr & 0x1000) >> 12][addr & 0x0FFF]
elif 0x2000 <= addr <= 0x3EFF:
addr &= 0x0FFF
if self.__cart.Mirror() == MIRROR.VERTICAL:
if 0x0000 <= addr <= 0x03FF:
data = self.__tblName[0][addr & 0x03FF]
elif 0x0400 <= addr <= 0x07FF:
data = self.__tblName[1][addr & 0x03FF]
elif 0x0800 <= addr <= 0x0BFF:
data = self.__tblName[0][addr & 0x03FF]
elif 0x0c00 <= addr <= 0x0FFF:
data = self.__tblName[1][addr & 0x03FF]
elif self.__cart.Mirror() == MIRROR.HORIZONTAL:
if 0x0000 <= addr <= 0x03FF:
data = self.__tblName[0][addr & 0x03FF]
elif 0x0400 <= addr <= 0x07ff:
data = self.__tblName[0][addr & 0x03FF]
elif 0x0800 <= addr <= 0x0bff:
data = self.__tblName[1][addr & 0x03FF]
elif 0x0c00 <= addr <= 0x0FFF:
data = self.__tblName[1][addr & 0x03FF]
elif 0x3F00 <= addr <= 0x3FFF:
addr &= 0x001f
if addr == 0x0010:
addr = 0x0000
elif addr == 0x0014:
addr = 0x0004
elif addr == 0x0018:
addr = 0x0008
elif addr == 0x001c:
addr = 0x000c
data = self.__tblPalette[addr] & (0x30 if self.__mask >= (1 << 7) else 0x3F)
return data
def ppuWrite(self, addr: int, data: int):
"""
1. Get address to PPU range
2. Judge ppu address
case 0x0000-0x1FFF : Pattern Tables
case 0x2000-0x2FFF : Name Tables
case 0x3000-0x3EFF : Mirrors
case 0x3F00-0x3F1F : Palette RAM
case 0x3F20-0x3FFF : Mirrors
"""
addr &= 0x3FFF
if self.__cart.ppuWrite(addr, data):
pass
elif 0x0000 <= addr <= 0x1FFF:
self.__tblPattern[(addr & 0x1000) >> 12][addr & 0x0FFF] = data
elif 0x2000 <= addr <= 0x3EFF:
addr &= 0x0FFF
if self.__cart.mirror == MIRROR.VERTICAL:
if 0x0000 <= addr <= 0x03FF:
self.__tblName[0][addr & 0x03FF] = data
elif 0x0400 <= addr <= 0x07ff:
self.__tblName[1][addr & 0x03FF] = data
elif 0x0800 <= addr <= 0x0Bff:
self.__tblName[0][addr & 0x03FF] = data
elif 0x0c00 <= addr <= 0x0FFF:
self.__tblName[1][addr & 0x03FF] = data
elif self.__cart.mirror == MIRROR.HORIZONTAL:
if 0x0000 <= addr <= 0x03FF:
self.__tblName[0][addr & 0x03FF] = data
elif 0x0400 <= addr <= 0x07FF:
self.__tblName[0][addr & 0x03FF] = data
elif 0x0800 <= addr <= 0x0BFF:
self.__tblName[1][addr & 0x03FF] = data
elif 0x0C00 <= addr <= 0x0FFF:
self.__tblName[1][addr & 0x03FF] = data
elif 0x3F00 <= addr <= 0x3FFF:
addr &= 0x001F
if addr == 0x0010:
addr = 0x0000
elif addr == 0x0014:
addr = 0x0004
elif addr == 0x0018:
addr = 0x0B08
elif addr == 0x001C:
addr = 0x000C
self.__tblPalette[addr] = data
def clock(self):
# Increment the background tile "pointer" one tile/column horizontally
def IncrementScrollX():
# Only if rendering is enabled
if (self.__mask & (1 << 3)) or (self.__mask & (1 << 4)):
if self.vram_addr & 0x0000001F == 31:
self.vram_addr &= 0x0000FFE0
self.vram_addr ^= (1 << 10)
else:
self.vram_addr += 1
def IncrementScrollY():
if (self.__mask & (1 << 3)) or (self.__mask & (1 << 4)):
if (self.vram_addr & 0x00007000) >> 12 < 7:
self.vram_addr += 0x1000
else:
self.vram_addr &= 0x00008FFF
if self.vram_addr & 0x000003E0 >> 5 == 29:
# Set the coarse_y = 0
self.vram_addr &= 0x0000FC1F
# Set the ~nametable_y
self.vram_addr ^= (1 << 11)
elif self.vram_addr & 0x000003E0 >> 5 == 31:
# Set the coarse_y = 0
self.vram_addr &= 0x0000FC1F
else:
# Set the coarse_y ++
self.vram_addr += (1 << 5)
def TransferAddressX():
if (self.__mask & (1 << 3)) or (self.__mask & (1 << 4)):
# set vram_name_tablex = tram_name_table.
self.vram_addr &= ~0x0400
self.vram_addr ^= (self.tram_addr & 0x00000400)
# coarse_x
self.vram_addr &= ~0x001F
self.vram_addr ^= (self.tram_addr & 0x0000001F)
def TransferAddressY():
if (self.__mask & (1 << 3)) or (self.__mask & (1 << 4)):
self.vram_addr &= ~0x7000
self.vram_addr ^= (self.tram_addr & 0x00007000)
self.vram_addr &= ~0x0800
self.vram_addr ^= (self.tram_addr & 0x00000800)
self.vram_addr &= ~0x03E0
self.vram_addr ^= (self.tram_addr & 0x000003E0)
def LoadBackgroundShifters():
self.bg_shifter_pattern_lo = (self.bg_shifter_pattern_lo & 0x0000FF00) | self.bg_next_tile_lsb
self.bg_shifter_pattern_hi = (self.bg_shifter_pattern_hi & 0x0000FF00) | self.bg_next_tile_msb
self.bg_shifter_attrib_lo = (self.bg_shifter_attrib_lo & 0x0000FF00) | (
0xFF if (self.bg_next_tile_attrib & 0x00000001) else 0x00)
self.bg_shifter_attrib_hi = (self.bg_shifter_attrib_hi & 0x0000FF00) | (
0xFF if (self.bg_next_tile_attrib & 0x00000002) else 0x00)
def UpdateShifters():
if self.__mask & 0x08:
self.bg_shifter_pattern_lo <<= 1
self.bg_shifter_pattern_lo &= 0x0000FFFF
self.bg_shifter_pattern_hi <<= 1
self.bg_shifter_pattern_hi &= 0x0000FFFF
self.bg_shifter_attrib_lo <<= 1
self.bg_shifter_attrib_lo &= 0x0000FFFF
self.bg_shifter_attrib_hi <<= 1
self.bg_shifter_attrib_hi &= 0x0000FFFF
if self.__mask & 0x08 and 1 <= self.__cycle < 258:
for x in range(self.sprite_count):
if self.spriteScanline[x].x > 0:
self.spriteScanline[x].x -= 1
else:
self.sprite_shifter_pattern_lo[x] <<= 1
self.sprite_shifter_pattern_hi[x] <<= 1
if -1 <= self.__scanline < 240:
if (self.__scanline == 0 and self.__cycle == 0 and self.odd_frame
and ((self.__mask & (1 << 3)) or (self.__mask & (1 << 4)))):
self.__cycle = 1
if self.__cycle == 1 and self.__scanline == -1:
# Effectively start of new frame, so clear vertical blank flag
self.__status &= 0x00000080 # Clear vertical_blank
self.__status &= 0x00000020 # Clear sprite_overflow
self.__status &= 0x00000040 # Clear sprite_zero_hit
for i in range(8):
self.sprite_shifter_pattern_lo[i] = 0
self.sprite_shifter_pattern_hi[i] = 0
if 2 <= self.__cycle < 258 or 321 <= self.__cycle < 338:
"""
2 <= self.__cycle < 258 : 这段时间是每条扫描线的主要渲染阶段，PPU 在这个范围内执行背景和精灵的像素绘制。
扫描线 240 到 260 是垂直空白期间（VBlank），此时屏幕不进行渲染，PPU 处理其他任务，如设置垂直空白标志、通知 CPU 当前帧已完成渲染等。
321 <= self.__cycle < 338 : 这是每条扫描线的最后一个部分，用于准备下一条扫描线的渲染数据。
"""
UpdateShifters()
flag = (self.__cycle - 1) % 8
if flag == 0:
LoadBackgroundShifters()
# Fetch the next background tile ID
self.bg_next_tile_id = self.ppuRead(0x2000 | (self.vram_addr & 0x00000FFF))
pass
elif flag == 2:
self.bg_next_tile_attrib = self.ppuRead(0x23C0 | (self.vram_addr & 0x00000800)
| (self.vram_addr & 0x00000400)
| ((self.vram_addr & 0x000003E0 >> 7) << 3)
| (self.vram_addr & 0x0000001F >> 2))
if (self.vram_addr & 0x000003E0 >> 5) & 0x02:
self.bg_next_tile_attrib >>= 4
if (self.vram_addr & 0x0000001F) & 0x02:
self.bg_next_tile_attrib >>= 2
self.bg_next_tile_attrib &= 0x00000003
pass
elif flag == 4:
addr = (self.__control & 0x00000010 << 8) + (self.bg_next_tile_id << 4) + (
self.vram_addr & 0x00007000 >> 12 + 0)
self.bg_next_tile_lsb = self.ppuRead(addr)
pass
elif flag == 6:
addr = (self.__control & 0x00000010 << 8) + (self.bg_next_tile_id << 4) + (
self.vram_addr & 0x7000 >> 12 + 8)
self.bg_next_tile_msb = self.ppuRead(addr)
pass
elif flag == 7:
IncrementScrollX()
pass
if self.__cycle == 256:
# End of a scanline, increase Y scroll
IncrementScrollY()
if self.__cycle == 257:
# Reset the x position to start a new Scanline
LoadBackgroundShifters()
TransferAddressX()
if self.__cycle == 338 or self.__cycle == 340:
#
self.bg_next_tile_id = self.ppuRead(0x2000 | (self.vram_addr & 0x00000FFF))
if 280 <= self.__cycle < 305:
if self.__scanline == -1:
TransferAddressY()
# Foreground Rendering
if self.__cycle == 257 and self.__scanline >= 0:
self.spriteScanline = [TILE(0xFF, 0xFF, 0xFF, 0xFF)] * 8
self.sprite_count = 0
for i in range(8):
self.sprite_shifter_pattern_lo[i] = 0
self.sprite_shifter_pattern_hi[i] = 0
nOAMEntry = 0
self.bSpriteZEroHitPossible = False
while nOAMEntry < 64 and self.sprite_count < 9:
diff = self.__scanline - self.OAM[nOAMEntry].y
if 0 <= diff < (16 if self.__control & 0x00000020 else 8) and self.sprite_count < 8:
if self.sprite_count < 8:
if nOAMEntry == 0:
self.bSpriteZEroHitPossible = True
self.spriteScanline[self.sprite_count] = self.OAM[nOAMEntry]
self.sprite_count += 1
nOAMEntry += 1
self.__status &= 0b11011111 if self.sprite_count >= 8 else 0xFF
if self.__cycle == 340:
sprite_pattern_bits_lo = 0xFF
sprite_pattern_bits_hi = 0xFF
sprite_pattern_addr_lo = 0xFF
sprite_pattern_addr_hi = 0xFF
for i in range(self.sprite_count):
if not self.__control & 0b00100000:
if not self.spriteScanline[i].attribute & 0x80:
sprite_pattern_addr_lo = ((self.__control & 0x08 << 9) |
(self.spriteScanline[i].id << 4) |
(self.__scanline - self.spriteScanline[i].y))
else:
sprite_pattern_addr_lo = ((self.__control & 0x08 << 9) |
(self.spriteScanline[i].id << 4) |
(7 - (self.__scanline - self.spriteScanline[i].y)))
else:
if not self.spriteScanline[i].attribute & 0x80:
if self.__scanline - self.spriteScanline[i].y < 8:
sprite_pattern_addr_lo = (((self.spriteScanline[i].id & 0x01) << 12) |
((self.spriteScanline[i].id & 0xFE) << 4) |
((self.__scanline - self.spriteScanline[i].y) & 0x07))
else:
sprite_pattern_addr_lo = (((self.spriteScanline[i].id & 0x01) << 12) |
(((self.spriteScanline[i].id & 0xFE) + 1) << 4) |
((self.__scanline - self.spriteScanline[i].y) & 0x07))
else:
if self.__scanline - self.spriteScanline[i].y < 8:
sprite_pattern_addr_lo = (((self.spriteScanline[i].id & 0x01) << 12) |
(((self.spriteScanline[i].id & 0xFE) + 1) << 4) |
((7 - (self.__scanline - self.spriteScanline[i].y)) & 0x07))
else:
sprite_pattern_addr_lo = (((self.spriteScanline[i].id & 0x01) << 12) |
((self.spriteScanline[i].id & 0xFE) << 4) |
((7 - (self.__scanline - self.spriteScanline[i].y)) & 0x07))
sprite_pattern_addr_hi = sprite_pattern_addr_lo + 8
sprite_pattern_bits_lo = self.ppuRead(sprite_pattern_addr_lo)
sprite_pattern_bits_hi = self.ppuRead(sprite_pattern_addr_hi)
if self.spriteScanline[i].attribute & 0x40:
def flipbyte(a):
a = (a & 0xF0) >> 4 | (a & 0x0F) << 4
a = (a & 0xCC) >> 2 | (a & 0x33) << 2
a = (a & 0xAA) >> 1 | (a & 0x55) << 1
return a
sprite_pattern_bits_lo = flipbyte(sprite_pattern_bits_lo)
sprite_pattern_bits_hi = flipbyte(sprite_pattern_bits_hi)
self.sprite_shifter_pattern_lo[i] = sprite_pattern_bits_lo
self.sprite_shifter_pattern_hi[i] = sprite_pattern_bits_hi
if self.__scanline == 240:
# Post Render Scanline - Do Nothing!
pass
if 241 <= self.__scanline < 261:
if self.__scanline == 241 and self.__cycle == 1:
self.__status |= 0b10000000
if self.__control & 0b10000000:
self.nmi = True
# Background
bg_pixel = 0x00
bg_palette = 0x00
if self.__mask & 0x08:
if self.__mask & 0x02 or self.__cycle >= 9:
bit_mux = 0x8000 >> self.fine_x
p0_pixel = 1 if (self.bg_shifter_pattern_lo & bit_mux) > 0 else 0
p1_pixel = 1 if (self.bg_shifter_pattern_hi & bit_mux) > 0 else 0
bg_pixel = (p1_pixel << 1) | p0_pixel
bg_pal0 = (self.bg_shifter_attrib_lo & bit_mux) > 0
bg_pal1 = (self.bg_shifter_attrib_hi & bit_mux) > 0
bg_palette = (bg_pal1 << 1) | bg_pal0
# Foreground
fg_pixel = 0x00
fg_palette = 0x00
fg_priority = 0x00
if self.__mask & 0x10 or self.__cycle >= 9:
self.bSpriteZeroBeingRendered = False
for i in range(self.sprite_count):
if self.spriteScanline[i].x == 0:
fg_pixel_lo = (self.sprite_shifter_pattern_lo[i] & 0x80) > 0
fg_pixel_hi = (self.sprite_shifter_pattern_hi[i] & 0x80) > 0
fg_pixel = (fg_pixel_hi << 1) | fg_pixel_lo
fg_palette = (self.spriteScanline[i].attribute & 0x03) + 0x04
fg_priority = (self.spriteScanline[i].attribute & 0x20) == 0
if fg_pixel != 0:
if i == 0:
self.bSpriteZeroBeingRendered = True
# Combine sprite and background
pixel = 0x00
palette = 0x00
if bg_pixel == 0 and fg_pixel == 0:
pixel = 0x00
palette = 0x00
elif bg_pixel == 0 and fg_pixel > 0:
pixel = fg_pixel
palette = fg_palette
elif bg_pixel > 0 and fg_pixel == 0:
pixel = bg_pixel
palette = bg_palette
elif bg_pixel > 0 and fg_pixel > 0:
if fg_priority:
pixel = fg_pixel
palette = fg_palette
else:
pixel = bg_pixel
palette = bg_palette
if self.bSpriteZEroHitPossible and self.bSpriteZeroBeingRendered:
if self.__mask & 0x80 and self.__mask & 0x10:
if not (self.__mask & 0x02 or self.__mask & 0x04):
if 9 <= self.__cycle < 258:
self.__status |= 0b01000000
else:
if 1 <= self.__cycle < 258:
self.__status |= 0b01000000
self.sprScreen.SetPixel(self.__cycle - 1, self.__scanline, self.GetColourFromPaletteRam(palette, pixel))
self.__cycle += 1
if self.__mask & 0x08 and self.__mask & 0x10:
if self.__cycle == 260 and self.__scanline < 240:
self.__cart.GetMapper().scanline()
if self.__cycle >= 341:
self.__cycle = 0
self.__scanline += 1
if self.__scanline >= 261:
self.__scanline = -1
self.frame_complete = True
self.odd_frame = not self.odd_frame