NES 2.0 size calculaton fixes

1 files changed, 80 insertions, 58 deletions

diff --git a/NesFile.cs b/NesFile.cs
index c7b850f..ce531c1 100644
--- a/NesFile.cs
+++ b/NesFile.cs
@@ -14,23 +14,25 @@ namespace com.clusterrr.Famicom.Containers
         /// <summary>

         /// PRG data

         /// </summary>

-        public IEnumerable<byte> PRG { 

-            get => Array.AsReadOnly(prg); 

-            set => prg = (value ?? new byte[0]).ToArray(); 

+        public IEnumerable<byte> PRG

+        {

+            get => Array.AsReadOnly(prg);

+            set => prg = (value ?? new byte[0]).ToArray();

         }

         /// <summary>

         /// CHR data (can be null if none)

         /// </summary>

-        public IEnumerable<byte> CHR { 

-            get => Array.AsReadOnly(chr); 

-            set => chr = (value ?? new byte[0]).ToArray(); 

+        public IEnumerable<byte> CHR

+        {

+            get => Array.AsReadOnly(chr);

+            set => chr = (value ?? new byte[0]).ToArray();

         }

         /// <summary>

         /// Trainer (can be null if none)

         /// </summary>

         public IEnumerable<byte> Trainer

         {

-            get => Array.AsReadOnly(trainer); 

+            get => Array.AsReadOnly(trainer);

             set

             {

                 if (value != null && value.Count() != 0 && value.Count() != 512)

@@ -41,9 +43,10 @@ namespace com.clusterrr.Famicom.Containers
         /// <summary>

         /// Miscellaneous ROM (NES 2.0 only, can be null if none)

         /// </summary>

-        public IEnumerable<byte> MiscellaneousROM { 

-            get => Array.AsReadOnly(miscellaneousROM); 

-            set => miscellaneousROM = (value ?? new byte[0]).ToArray(); 

+        public IEnumerable<byte> MiscellaneousROM

+        {

+            get => Array.AsReadOnly(miscellaneousROM);

+            set => miscellaneousROM = (value ?? new byte[0]).ToArray();

         }

         /// <summary>

         /// Mapper number

@@ -726,6 +729,7 @@ namespace com.clusterrr.Famicom.Containers
             if (prg == null) prg = new byte[0];

             if (chr == null) chr = new byte[0];

             if (trainer == null) trainer = new byte[0];

+            /*

             if ((prg.Length % 0x4000) != 0)

             {

                 var padding = 0x4000 - (prg.Length % 4000);

@@ -738,6 +742,8 @@ namespace com.clusterrr.Famicom.Containers
                 if (padding > 0)

                     Array.Resize(ref chr, chr.Length + padding);

             }

+            */

+            ulong prgSizePadded, chrSizePadded;

             if (Version == iNesVersion.iNES)

             {

                 if (Console == ConsoleType.Extended)

@@ -748,10 +754,12 @@ namespace com.clusterrr.Famicom.Containers
                     throw new InvalidDataException("Submapper supported by NES 2.0 only");

                 var length16k = prg.Length / 0x4000;

                 if (length16k > 0xFF) throw new ArgumentOutOfRangeException("PRG size is too big for iNES, use NES 2.0 instead");

-                header[4] = (byte)(prg.Length / 0x4000);

+                header[4] = (byte)Math.Ceiling((double)prg.Length / 0x4000);

+                prgSizePadded = header[4] * 0x4000UL;

                 var length8k = chr.Length / 0x2000;

                 if (length8k > 0xFF) throw new ArgumentOutOfRangeException("CHR size is too big for iNES, use NES 2.0 instead");

-                header[5] = (byte)(CHR.Count() / 0x2000);

+                header[5] = (byte)Math.Ceiling((double)chr.Length / 0x2000);

+                chrSizePadded = header[5] * 0x2000UL;

                 // Hard-wired nametable mirroring type

                 if (Mirroring == MirroringType.Vertical)

                     header[6] |= 1;

@@ -779,31 +787,31 @@ namespace com.clusterrr.Famicom.Containers
             }

             else if (Version == iNesVersion.NES20)

             {

-                var length16k = prg.Length / 0x4000;

+                var length16k = (uint)Math.Ceiling((double)prg.Length / 0x4000);

                 if (length16k <= 0xEFF)

                 {

                     header[4] = (byte)(length16k & 0xFF);

                     header[9] |= (byte)(length16k >> 8);

+                    prgSizePadded = length16k * 0x4000;

                 }

                 else

                 {

-                    (long padding, int exponent, int multiplier) = CalculateExponent(prg.Length);

-                    if (padding > 0)

-                        Array.Resize(ref prg, (int)(prg.Length + padding));

+                    byte exponent, multiplier;

+                    (exponent, multiplier, prgSizePadded) = SizeToExponent((ulong)prg.Length);

                     header[4] = (byte)((exponent << 2) | (multiplier & 3));

                     header[9] |= 0x0F;

                 }

-                var length8k = CHR.Count() / 0x2000;

+                var length8k = (uint)Math.Ceiling((double)chr.Length / 0x2000);

                 if (length8k <= 0xEFF)

                 {

                     header[5] = (byte)(length8k & 0xFF);

                     header[9] |= (byte)((length8k >> 4) & 0xF0);

+                    chrSizePadded = length8k * 0x2000;

                 }

                 else

                 {

-                    (long padding, int exponent, int multiplier) = CalculateExponent(CHR.Count());

-                    if (padding > 0)

-                        Array.Resize(ref chr, (int)(chr.Length + padding));

+                    byte exponent, multiplier;

+                    (exponent, multiplier, chrSizePadded) = SizeToExponent((ulong)chr.Length);

                     header[5] = (byte)((exponent << 2) | (multiplier & 3));

                     header[9] |= 0xF0;

                 }

@@ -830,18 +838,18 @@ namespace com.clusterrr.Famicom.Containers
                 // Mapper number D8..D11

                 header[8] |= (byte)((Mapper >> 8) & 0x0F);

                 header[8] |= (byte)(Submapper << 4);

-                var prgRamBitSize = GetBitSize((int)PrgRamSize);

-                var prgNvRamBitSize = GetBitSize((int)PrgNvRamSize);

                 // PRG RAM (volatile) shift count

-                header[10] |= (byte)(Math.Max(prgRamBitSize - 7, 0) & 0x0F);

+                var prgRamBitSize = PrgRamSize > 0 ? Math.Max(1, (int)Math.Ceiling(Math.Log(PrgRamSize, 2)) - 6) : 0;

+                header[10] |= (byte)(prgRamBitSize & 0x0F);

                 // PRG-NVRAM/EEPROM (non-volatile) shift count

-                header[10] |= (byte)((Math.Max(prgNvRamBitSize - 7, 0) << 4) & 0xF0);

-                var chrRamBitSize = GetBitSize((int)ChrRamSize);

-                var chrNvRamBitSize = GetBitSize((int)ChrNvRamSize);

+                var prgNvRamBitSize = PrgNvRamSize > 0 ? Math.Max(1, (int)Math.Ceiling(Math.Log(PrgNvRamSize, 2)) - 6) : 0;

+                header[10] |= (byte)((prgNvRamBitSize << 4) & 0xF0);

                 // CHR-RAM size (volatile) shift count

-                header[11] |= (byte)(Math.Max(chrRamBitSize - 7, 0) & 0x0F);

+                var chrRamBitSize = ChrRamSize > 0 ? Math.Max(1, (int)Math.Ceiling(Math.Log(ChrRamSize, 2)) - 6) : 0;

+                header[11] |= (byte)(chrRamBitSize & 0x0F);

                 // CHR-NVRAM size (non-volatile) shift count

-                header[11] |= (byte)((Math.Max(chrNvRamBitSize - 7, 0) << 4) & 0xF0);

+                var chrNvRamBitSize = ChrNvRamSize > 0 ? Math.Max(1, (int)Math.Ceiling(Math.Log(ChrNvRamSize, 2)) - 6) : 0;

+                header[11] |= (byte)((chrNvRamBitSize << 4) & 0xF0);

                 // CPU/PPU timing mode

                 header[12] |= (byte)((byte)Region & 3);

                 switch (Console)

@@ -868,58 +876,72 @@ namespace com.clusterrr.Famicom.Containers
                 if (Trainer != null)

                     data.AddRange(Trainer);

                 data.AddRange(prg);

+                data.AddRange(Enumerable.Repeat<byte>(0xFF, (int)prgSizePadded - prg.Length));

                 data.AddRange(chr);

+                data.AddRange(Enumerable.Repeat<byte>(0xFF, (int)chrSizePadded - chr.Length));

                 if (MiscellaneousROMsCount > 0 || (MiscellaneousROM != null && MiscellaneousROM.Count() > 0))

                 {

                     if (MiscellaneousROMsCount == 0)

                         throw new InvalidDataException("MiscellaneousROMsCount is zero while MiscellaneousROM is not empty");

                     if (MiscellaneousROM == null)

-                        throw new InvalidDataException("MiscellaneousROM is null while MiscellaneousROMsCount is not zero");

+                        throw new InvalidDataException("MiscellaneousROM is empty while MiscellaneousROMsCount is not zero");

                     data.AddRange(MiscellaneousROM);

                 }

             }

             return data.ToArray();

         }

 

-        private static (long Padding, int Exponent, int Multiplier) CalculateExponent(long value)

+        private static ulong ExponentToSize(byte exponent, byte multiplier)

+            => (1UL << exponent) * (ulong)(multiplier * 2 + 1);

+

+        private static (byte Exponent, byte Multiplier, ulong Padded) SizeToExponent(ulong value)

         {

-            // calculating bits required to store number

-            int bitsize = GetBitSize(value);

-            // check if we need to add padding

-            long padding = 0;

-            if ((value & ((1 << (bitsize - 3)) - 1)) != 0)

+            if (value == 0) return (0, 0, 1);

+            if (value < 8)

             {

-                // pad to round value

-                padding = (1L << bitsize) - (value & ((1L << bitsize) - 1));

-                bitsize = GetBitSize(value + padding);

+                var r = SizeToExponent(value << 3);

+                return ((byte)(r.Exponent - 3), r.Multiplier, r.Padded >> 3);

             }

-            int multiplier = 0;

-            switch (value >> (bitsize - 3))

+

+            // Calculate bits required to store number

+            byte bitsize = 0;

+            while (value >> bitsize > 0) bitsize++;

+

+            // Split it into two parts

+            var major = value >> (bitsize - 3);

+            var minor = value & (ulong)~(0b111 << (bitsize - 3));

+

+            // Round up

+            if (minor != 0) major++;

+

+            byte e, m;

+            switch (major)

             {

-                case 4: // 100

-                    multiplier = 0;

+                case 0b100:

+                    e = (byte)(bitsize - 1);

+                    m = 0; // 0*2+1=1

+                    break;

+                case 0b101:

+                    e = (byte)(bitsize - 3);

+                    m = 2; // 2*2+1=5

                     break;

-                case 5: // 101

-                    bitsize -= 2;

-                    multiplier = 2; // m*2+1 = 5

+                case 0b110:

+                    e = (byte)(bitsize - 2);

+                    m = 1; // 1*2+1=3

                     break;

-                case 6: // 110

-                    bitsize -= 1;

-                    multiplier = 1; // m*2+1 = 3;

+                case 0b111:

+                    e = (byte)(bitsize - 3);

+                    m = 3; // 3*2+1=7

                     break;

-                case 7: // 111

-                    bitsize -= 2;

-                    multiplier = 3; // m*2+1 = 7

+                case 0b1000:

+                    e = (byte)bitsize;

+                    m = 0; // 0*2+1=1

                     break;

+                default:

+                    throw new InvalidProgramException();

             }

-            return (padding, bitsize - 1, multiplier);

-        }

 

-        private static int GetBitSize(long value)

-        {

-            int bitsize = 0;

-            while (value >> bitsize > 0) bitsize++;

-            return bitsize;

+            return (e, m, ExponentToSize(e, m));

         }

 

         /// <summary>