| 6 | ) |
| 7 | |
| 8 | type PPU struct { |
| 9 | Memory // memory interface |
| 10 | console *Console // reference to parent object |
| 11 | |
| 12 | Cycle int // 0-340 |
| 13 | ScanLine int // 0-261, 0-239=visible, 240=post, 241-260=vblank, 261=pre |
| 14 | Frame uint64 // frame counter |
| 15 | |
| 16 | // storage variables |
| 17 | paletteData [32]byte |
| 18 | nameTableData [2048]byte |
| 19 | oamData [256]byte |
| 20 | front *image.RGBA |
| 21 | back *image.RGBA |
| 22 | |
| 23 | // PPU registers |
| 24 | v uint16 // current vram address (15 bit) |
| 25 | t uint16 // temporary vram address (15 bit) |
| 26 | x byte // fine x scroll (3 bit) |
| 27 | w byte // write toggle (1 bit) |
| 28 | f byte // even/odd frame flag (1 bit) |
| 29 | |
| 30 | register byte |
| 31 | |
| 32 | // NMI flags |
| 33 | nmiOccurred bool |
| 34 | nmiOutput bool |
| 35 | nmiPrevious bool |
| 36 | nmiDelay byte |
| 37 | |
| 38 | // background temporary variables |
| 39 | nameTableByte byte |
| 40 | attributeTableByte byte |
| 41 | lowTileByte byte |
| 42 | highTileByte byte |
| 43 | tileData uint64 |
| 44 | |
| 45 | // sprite temporary variables |
| 46 | spriteCount int |
| 47 | spritePatterns [8]uint32 |
| 48 | spritePositions [8]byte |
| 49 | spritePriorities [8]byte |
| 50 | spriteIndexes [8]byte |
| 51 | |
| 52 | // $2000 PPUCTRL |
| 53 | flagNameTable byte // 0: $2000; 1: $2400; 2: $2800; 3: $2C00 |
| 54 | flagIncrement byte // 0: add 1; 1: add 32 |
| 55 | flagSpriteTable byte // 0: $0000; 1: $1000; ignored in 8x16 mode |
| 56 | flagBackgroundTable byte // 0: $0000; 1: $1000 |
| 57 | flagSpriteSize byte // 0: 8x8; 1: 8x16 |
| 58 | flagMasterSlave byte // 0: read EXT; 1: write EXT |
| 59 | |
| 60 | // $2001 PPUMASK |
| 61 | flagGrayscale byte // 0: color; 1: grayscale |
| 62 | flagShowLeftBackground byte // 0: hide; 1: show |
| 63 | flagShowLeftSprites byte // 0: hide; 1: show |
| 64 | flagShowBackground byte // 0: hide; 1: show |
| 65 | flagShowSprites byte // 0: hide; 1: show |
nothing calls this directly
no outgoing calls
no test coverage detected