I use CMRC for resource management.
For some god-forsaken reason, gcc builds fail both on Mac and Windows. MSVC and clang should work as expected, bearing in mind the specifics of each one's C++ implementation.
cd ~/NESEmu
pip3 install conan
conan remote add bincrafters https://api.bintray.com/conan/bincrafters/public-conan
Visual studio has a weird cmake/conan interaction explained here:
https://docs.conan.io/en/1.3/howtos/vs2017_cmake.html
Furthermore, the contents of .conan/profiles/default which contain the settings that I
used for compiling under VS and MSVC are as follows:
conan install . -if=C:/Users/elvircrn/CMakeBuilds/0730974a-797b-6738-a0b9-9daee0626596/build/x64-Debug --build=missing -s os=Windows -s os_build=Windows -s arch=x86_64 -s arch_build=x86_64 -s build_type=Release -s compiler="Visual Studio" -s compiler.version=15
conan install . --install-folder=cmake-build-debug --build=missing -s compiler=apple-clang -s compiler.version=10.0 -s compiler.libcxx=libc++ -s build_type=Debug
Refactor branches into a single method
0 = 4E (N)
1 = 45 (E)
2 = 53 (S)
3 = 1A (Character Break, necessary!)
(Bytes 4->8-15 Can BE MODIFIED!)
4 = PRG (Hex number depends on size of PRG file)
5 = CHR (Hex number depends on size of CHR file)
6 = Mapper 0-15/ V or H Mirroring, Battery, 4 Screen VRAM, Trainer Switches
Also is used as the "Ones" place holder digit for the extended iNES Header
format. (See Sect. 2)
7 = Mappers 16-?, the extended iNES Header format "Tens" place holder digit.
Again (See Sect. 2 for details on how this is set up.)
8->15 = Not used at this tume but MUST BE ALL ZEROS or games will not work.
0 = Always zero 1 = Always 1
- = Not used ? = Unknown
+---------+----------------------------------------------------------+
| Address | Description |
+---------+----------------------------------------------------------+
| $2000 | PPjkU Control Register #1 (W) [PPUCNT0] |
| | %vMsbpiNN |
| | v = execute NMI on VBlank |
| | 1 = Enabled |
| | M = PPU Selection (unused) |
| | 0 = Master |
| | 1 = Slave |
| | s = Sprite Size |
| | 0 = 8x8 |
| | 1 = 8x16 |
| | b = Background Pattern Table Address |
| | 0 = $0000 (VRAM) |
| | 1 = $1000 (VRAM) |
| | p = Sprite Pattern Table Address |
| | 0 = $0000 (VRAM) |
| | 1 = $1000 (VRAM) |
| | i = PPU Address Increment |
| | 0 = Increment by 1 |
| | 1 = Increment by 32 |
| | NN = Name Table Address |
| | 00 = $2000 (VRAM) |
| | 01 = $2400 (VRAM) |
| | 10 = $2800 (VRAM) |
| | 11 = $2C00 (VRAM) |
| | |
| | NOTE: Bit #6 (M) has no use, as there is only one (1) |
| | PPU installed in all forms of the NES and Famicom. |
+---------+----------------------------------------------------------+
| $2001 | PPU Control Register #2 (W) [PPUCNT1] |
| | %fffpcsit |
| | fff = Full Background Colour |
| | 000 = Black |
| | 001 = Red |
| | 010 = Blue |
| | 100 = Green |
| | p = Sprite Visibility |
| | 1 = Display |
| | c = Background Visibility |
| | 1 = Display |
| | s = Sprite Clipping |
| | 0 = Sprites not displayed in left |
| | 8-pixel column |
| | 1 = No clipping |
| | i = Background Clipping |
| | 0 = Background not displayed in |
| | left 8-pixel column |
| | 1 = No clipping |
| | t = Display Type |
| | 0 = Colour display |
| | 1 = Mono-type (B&W) display |
+---------+----------------------------------------------------------+
- Selects the Name table to display
- Sets the ppu address increment (for reading/writing)
- Sets the address within the pattern table for sprite tiles
- Sets the address within the pattern table for background tiles
- Selects the sprite size (8x8 or 8x16)
- Sets whether to execute an interupt when drawing sprite 0
- Sets whether to execute an interupt during the Vblank period
- Sets the disply to color or mono-tone
- Sets whether to clip the left 8 pixels of the background
- Sets whether to clip sprites within the left 8 pixels of the background
- Sets whether to display the screen or not
- Selects the screen background color (black, red, blue, green)
- Returns whether PPU is in a Vblank period
- Returns whether there are more than 8 sprites on the current scanline
- Returns whether sprite 0 has been drawn on the current scanline
Every instruction takes at least two cycles.
immediate +0
zeropage +1
zeropage,x +2
zeropage,y +2
absolute +2
absolute,x +2
absolute,y +2
(indirect,x) +4
(indirect),y +3
The OAM (Object Attribute Memory) is internal memory inside the PPU that contains a display list of up to 64 sprites, where each sprite's information occupies 4 bytes.
Only used by branches, no need to call tick().
PHP +1
PHA +1
PLA +2
PLP +2
Instructions starting with T do not require any extra cycles!
Branches take an extra cycle if the branch is taken and another if zero is crossed(not calculated).
Do not take any aditional cycles.
Any instruction that uses this mode does not take any additional cycles
Do not take any aditional cycles.
Not affected by zeropage crossing
zeropage +1
zeropage,x +2
zeropage,y +2
absolute +2
(indirect,x) +4
absolute,x +3
absolute,y +3
(indirect),y +4
4 additional cycles. RTI -> PLP(Pop8) +2 Pop16 +2? RTS -> Pop16 +2
zeropage +1
absolute +2
immediate +0
zeropage +1
absolute +2
zeropage,x +2
absolute,x [+2]
absolute,y [+2]
(indirect,x) +4
(indirect),y [+3]
Not affected by zeropage crossing
zeropage +3
zeropage,x +4
absolute +4
absolute,x +5
INX, INY, DEX and DEY do not require any additional cycles.
absolute +1
indirect +3
absolute +4
immediate +0
zeropage +1
zeropage,x +2
absolute +2
absolute,x [+2]
absolute,y [+2]
(indirect,x) +4
(indirect),y [+3]
accumulator +0
zeropage +3
zeropage,s +4
absolute +4
absolute,x +5
immediate +0
zeropage +1
zeropage,x +2
absolute +2
absolute,x [+2]
absolute,y [+2]
(indirect,x) +4
(indirect),y [+3]
http://web.textfiles.com/games/ http://web.textfiles.com/games/nestech.txt
All the graphical information is stored within the 16kb memory of the Picture Processing Unit (PPU).
The first area of PPU memory is known as the "Pattern Tables." The pattern tables are 8kb in size, which is usually split in half, one part for the background, the other for sprites. The usage of the pattern tables is determined by the PPU control registers. All graphics are stored in 8x8 pixel "tiles" within the pattern tables which are arranged to form backgrounds and sprites. The pattern tables (also known as VROM) contains half the graphics information for these tiles. The NES is capable of displaying 16 colors at once, since each pixel is 4 bits that are a lookup of the palette. The pattern table contains the low two bits, and the upper two either come from the attribute table (for the background) or from sprite ram (for sprites).
Some roms contain what is known as CHR-RAM. CHR-RAM stands for CHaRacter RAM and contains 8kb banks of pattern tables which can be swapped in and out of the PPU via an MMC. This saves the trouble of copying it from within the program code to the PPU like games without CHR-RAM do.
The second area of PPU memory is known as "Name Tables." There are usually two, although there are addresses for 4. The other two are mirrors of the actual tables, which is determined by the mirroring bit of the .NES header. Each name table is 960 bytes, which corresponds with 960 8x8 tiles that make up the background. The background is 32x30 tiles, or 256x240 pixels. In a NTSC NES, however, the top and bottom 8 lines are not displayed, making the actual resolution 256x224. Note that some games use only one name table, and others can use 4. These settings are dependant on the memory mapper used.
Paired with each name table is an attribute table. These tables contain the upper two bits of each pixel's color that are matched with the lower two bits from the pattern table. However, the attribute table is only 64 bytes in size, meaning that each byte contains the upper two bits for a group of 4x4 tiles (or 32x32 pixels). This puts a limitation on your choice of colors in the background. However, you can get around the attribute table limitation by using MMC5, which allows you to use 4 name tables and the upper two bits for each individual tile. For more information, read Y0SHi's very informative NESTECH.DOC
Also stored in PPU memory are two 16 color palettes. One is used for the background, the other for sprites. These are not actual rgb palettes, but lookup tables of a 256 color palette that the PPU translates into tv signals. You can modify the values stored in the palette, allowing you to create many effects such as fades, flashing, or transparency.
There is an independent area of memory known as sprite ram, which is 256 bytes in size. This memory stores 4 bytes of information for 64 sprites. These 4 bytes contain the x and y location of the sprite on the screen, the upper two color bits, the tile index number (pattern table tile of the sprite), and information about flipping (horizontal and vertical), and priority (behind/on top of background). Sprite ram can be accessed byte-by-byte through the NES registers, or also can be loaded via DMA transfer through another register.
There are various other aspects of the PPU that can be controlled via several nes registers. Here's a list of registers and what they do:
PPU Control register 1 (PPUCTRL0):
- Selects the Name table to display
- Sets the ppu address increment (for reading/writing)
- Sets the address within the pattern table for sprite tiles
- Sets the address within the pattern table for background tiles
- Selects the sprite size (8x8 or 8x16)
- Sets whether to execute an interupt when drawing sprite 0
- Sets whether to execute an interupt during the Vblank period
PPU Control register 2 (PPUCTRL1):
- Sets the disply to color or mono-tone
- Sets whether to clip the left 8 pixels of the background
- Sets whether to clip sprites within the left 8 pixels of the background
- Sets whether to display the screen or not
- Selects the screen background color (black, red, blue, green)
PPU Status register (PPUSTAT):
- Returns whether PPU is in a Vblank period
- Returns whether there are more than 8 sprites on the current scanline
- Returns whether sprite 0 has been drawn on the current scanline
Background Scroll (BGSCROLL):
- Sets the horizontal and vertical scroll (written to twice)