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Be less lazy about N64 header detection in byteswapper 

fixes 82c3b471a, 9660c16a0
This commit is contained in:
YoshiRulz 2022-12-05 04:53:20 +10:00
parent 9660c16a0a
commit abeaa2a106
No known key found for this signature in database
GPG Key ID: C4DE31C245353FB7
4 changed files with 57 additions and 37 deletions
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2
src/BizHawk.Client.Common/RomGame.cs
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@ -96,7 +96,7 @@ namespace BizHawk.Client.Common
RomData = DeInterleaveSMD(RomData);
}
if (file.Extension is ".n64" or ".v64" or ".z64") N64RomByteswapper.ToZ64Native(RomData); //TODO don't use file extension for N64 rom detection (yes that means detecting all formats before converting to Z64)
if (file.Extension is ".n64" or ".v64" or ".z64") _ = N64RomByteswapper.ToZ64Native(RomData); //TODO don't use file extension for N64 rom detection (yes that means detecting all formats before converting to Z64)
// note: this will be taking several hashes, of a potentially large amount of data.. yikes!
GameInfo = Database.GetGameInfo(RomData, file.Name);

17
src/BizHawk.Client.EmuHawk/debug/N64RomByteswapToolForm.cs
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@ -51,19 +51,12 @@ namespace BizHawk.Client.EmuHawk.ForDebugging
try
{
var rom = File.ReadAllBytes(txtBaseFile.Text);
switch (comboFormats.SelectedIndex) // can't have Action<Span<byte>> (System.Buffers.SpanAction isn't suitable) or I'd be able to have a tiny switch expr >:( --yoshi
_ = comboFormats.SelectedIndex switch
{
case 0:
N64RomByteswapper.ToN64LittleEndian(rom);
break;
case 1:
N64RomByteswapper.ToV64ByteSwapped(rom);
break;
case 2:
default:
N64RomByteswapper.ToZ64Native(rom);
break;
}
0 => N64RomByteswapper.ToN64LittleEndian(rom),
1 => N64RomByteswapper.ToV64ByteSwapped(rom),
_ => N64RomByteswapper.ToZ64Native(rom)
};
File.WriteAllBytes(txtTargetFile.Text, rom);
this.ModalMessageBox($"wrote {txtTargetFile.Text}\n{SHA1Checksum.ComputePrefixedHex(rom)}");
}

63
src/BizHawk.Emulation.Common/N64RomByteswapper.cs
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@ -1,4 +1,5 @@
using System;
using System.Runtime.InteropServices;
using BizHawk.Common;
@ -8,31 +9,67 @@ namespace BizHawk.Emulation.Common
/// <remarks>http://n64dev.org/romformats.html</remarks>
public static class N64RomByteswapper
{
private static readonly byte[] MAGIC_BYTES_LE = { 0x37, 0x80, 0x40, 0x12 };
/// <remarks>not actually magic, just always the same in commercial carts? https://n64brew.dev/wiki/ROM_Header works all the same</remarks>
private static readonly byte[] MAGIC_BYTES = { 0x80, 0x37, 0x12, 0x40 };
private static readonly byte[] MAGIC_BYTES_NATIVE = { 0x80, 0x37, 0x12, 0x40 };
private static readonly byte[] MAGIC_BYTES_SWAPPED = { 0x40, 0x12, 0x37, 0x80 };
/// <summary>ensures <paramref name="rom"/> is in the rare little-endian (<c>.n64</c>) format, mutating it in-place if necessary</summary>
public static void ToN64LittleEndian(Span<byte> rom)
/// <returns><see langword="true"/> iff <paramref name="rom"/> was one of the 3 valid formats</returns>
public static bool ToN64LittleEndian(Span<byte> rom)
{
if (rom[0] == MAGIC_BYTES[0]) EndiannessUtils.MutatingByteSwap32(rom); // native (.z64)
else if (rom[0] == MAGIC_BYTES[1]) EndiannessUtils.MutatingShortSwap32(rom); // byte-swapped (.v64)
// else already rare little-endian .n64
var romMagicBytes = rom.Slice(start: 0, length: 4);
if (romMagicBytes.SequenceEqual(MAGIC_BYTES_NATIVE))
{
EndiannessUtils.MutatingByteSwap32(rom);
return true;
}
if (romMagicBytes.SequenceEqual(MAGIC_BYTES_SWAPPED))
{
EndiannessUtils.MutatingShortSwap32(rom);
return true;
}
return romMagicBytes.SequenceEqual(MAGIC_BYTES_LE);
}
/// <summary>ensures <paramref name="rom"/> is in the byte-swapped (<c>.v64</c>) format, mutating it in-place if necessary</summary>
public static void ToV64ByteSwapped(Span<byte> rom)
/// <returns><see langword="true"/> iff <paramref name="rom"/> was one of the 3 valid formats</returns>
public static bool ToV64ByteSwapped(Span<byte> rom)
{
if (rom[0] == MAGIC_BYTES[0]) EndiannessUtils.MutatingByteSwap16(rom); // native (.z64)
else if (rom[0] == MAGIC_BYTES[3]) EndiannessUtils.MutatingShortSwap32(rom); // rare little-endian .n64
// else already byte-swapped (.v64)
var romMagicBytes = rom.Slice(start: 0, length: 4);
if (romMagicBytes.SequenceEqual(MAGIC_BYTES_NATIVE))
{
EndiannessUtils.MutatingByteSwap16(rom);
return true;
}
if (romMagicBytes.SequenceEqual(MAGIC_BYTES_SWAPPED)) return true;
if (romMagicBytes.SequenceEqual(MAGIC_BYTES_LE))
{
EndiannessUtils.MutatingShortSwap32(rom);
return true;
}
return false;
}
/// <summary>ensures <paramref name="rom"/> is in the native (<c>.z64</c>) format, mutating it in-place if necessary</summary>
public static void ToZ64Native(Span<byte> rom)
/// <returns><see langword="true"/> iff <paramref name="rom"/> was one of the 3 valid formats</returns>
public static bool ToZ64Native(Span<byte> rom)
{
if (rom[0] == MAGIC_BYTES[1]) EndiannessUtils.MutatingByteSwap16(rom); // byte-swapped (.v64)
else if (rom[0] == MAGIC_BYTES[3]) EndiannessUtils.MutatingByteSwap32(rom); // rare little-endian .n64
// else already native (.z64)
var romMagicBytes = rom.Slice(start: 0, length: 4);
if (romMagicBytes.SequenceEqual(MAGIC_BYTES_NATIVE)) return true;
if (romMagicBytes.SequenceEqual(MAGIC_BYTES_SWAPPED))
{
EndiannessUtils.MutatingByteSwap16(rom);
return true;
}
if (romMagicBytes.SequenceEqual(MAGIC_BYTES_LE))
{
EndiannessUtils.MutatingByteSwap32(rom);
return true;
}
return false;
}
}
}

12
src/BizHawk.Emulation.Cores/Consoles/Nintendo/Ares64/Ares64.cs
View File

@ -69,17 +69,7 @@ namespace BizHawk.Emulation.Cores.Consoles.Nintendo.Ares64
// TODO: this is normally handled frontend side
// except XML files don't go through RomGame
// (probably should, but needs refactoring)
foreach (var d in lp.Roms.Select(static r => r.RomData))
{
// magic N64 rom bytes are 0x80, 0x37, 0x12, 0x40
// this should hopefully only ever detect N64 roms and not other kinds of files sent through here...
if ((d[1] is 0x80 && d[0] is 0x37 && d[3] is 0x12 && d[2] is 0x40) // .v64 byteswapped
|| (d[3] is 0x80 && d[2] is 0x37 && d[1] is 0x12 && d[0] is 0x40) // .n64 little-endian
|| (d[0] is 0x80 && d[1] is 0x37 && d[2] is 0x12 && d[3] is 0x40)) // .z64 native
{
N64RomByteswapper.ToZ64Native(d);
}
}
foreach (var r in lp.Roms) _ = N64RomByteswapper.ToZ64Native(r.RomData); // no-op if N64 magic bytes not present
var gbRoms = lp.Roms.FindAll(r => IsGBRom(r.FileData)).Select(r => r.FileData).ToArray();
var rom = lp.Roms.Find(r => !gbRoms.Contains(r.FileData) && (char)r.RomData[0x3B] is 'N' or 'C')?.RomData;