Add .nes pattern file

README.md

@@ -70,6 +70,7 @@ Everything will immediately show up in ImHex's Content Store and gets bundled wi
 | NACP | | [`patterns/nacp.hexpat`](patterns/nacp.hexpat) | Nintendo Switch NACP files |
 | NBT | | [`patterns/nbt.hexpat`](patterns/nbt.hexpat) | Minecraft NBT format |
 | NE   | | [`patterns/ne.hexpat`](patterns/ne.hexpat) | NE header and Standard NE fields |
+| nes   | | [`patterns/nes.hexpat`](patterns/nes.hexpat) | .nes file format |
 | NRO | | [`patterns/nro.hexpat`](patterns/nro.hexpat) | Nintendo Switch NRO files |
 | NTAG | | [`patterns/ntag.hexpat`](patterns/ntag.hexpat) | NTAG213/NTAG215/NTAG216, NFC Forum Type 2 Tag compliant IC |
 | OGG | `audio/ogg` | [`patterns/ogg.hexpat`](patterns/ogg.hexpat) | OGG Audio format |

patterns/nes.hexpat

@@ -0,0 +1,87 @@
+#pragma author gmestanley
+#pragma description .nes file format
+
+#include <std/mem.pat>
+#include <std/string.pat>
+
+bitfield iNES07Flags {
+	mirroringIsVertical : 1;
+	batterybackedPRGRAM : 1;
+	trainerOf512Bytes : 1;
+	ignoreMirroring : 1;
+	mapperLowerNybble : 4;
+	vsUnisystem : 1;
+	playchoice10 : 1;
+	nes2Format : 2 [[name("nes2.0Format")]];
+	mapperHigherNybble : 4;
+} [[name("iNES0.7Flags")]];
+
+bitfield Flags9 {
+	isPAL : 1;
+	padding : 7;
+};
+
+bitfield Flags10 {
+	tvSystem : 2;
+	padding : 2;
+	prgRAM : 1;
+	busConflicts : 1;
+	padding : 2;
+};
+
+struct iNESFlags {
+	iNES07Flags ines07Flags [[name("ines0.7Flags")]];
+	if (!ines07Flags.nes2Format) {
+		u8 prgRAM8KBMultiplier;
+		Flags9 flags9;
+		Flags10 flags10;
+		restLength = 5;
+	}
+	else {
+		restLength = 9;
+	}
+};
+
+u8 restLength;
+
+struct Header {
+	char identifier[4];
+	u8 prgROM16KBMultiplier;
+	u8 chrROM8KBMultiplier;
+	iNESFlags inesFlags;
+	char rest[restLength];
+};
+
+Header header @ 0x00;
+
+enum EncodingType : u8 {
+	ASCII = 1
+};
+
+struct OfficialHeader {
+	char title[16] [[hex::spec_name("Title Registration Area")]];
+	u16 programChecksum;
+	u16 characterChecksum;
+	u8 memorySize [[hex::spec_name("Cartridge Memory Size")]];
+	u8 cartridgeType;
+	EncodingType encodingType [[hex::spec_name("Registration Character Type Distinction")]];
+	u8 titleLength [[hex::spec_name("Registration Characters Count")]];
+	u8 makerID [[hex::spec_name("Maker Code")]];
+	u8 complementaryChecksum;
+};
+
+union OfficialHeaderUnion {
+	u8 miscellaneousData[26];
+	OfficialHeader officialHeader;
+};
+
+struct PRGROM {
+	u8 data[16384*header.prgROM16KBMultiplier-32];
+	OfficialHeaderUnion officialHeaderUnion;
+	u16 nmi;
+	u16 entryPoint;
+	u16 externalIRQ;
+};
+
+PRGROM prgROM @ sizeof(header);
+u8 chrROM[8192*header.chrROM8KBMultiplier] @ sizeof(header)+sizeof(prgROM);