pkNX/pkNX.Structures/CodePattern.cs

using System;
using System.Diagnostics;

namespace pkNX.Structures
{
    public static class CodePattern
    {
        /// <summary>
        /// Finds a provided <see cref="pattern"/> within the supplied <see cref="array"/>.
        /// </summary>
        /// <param name="array">Array to look in</param>
        /// <param name="pattern">Pattern to look for</param>
        /// <param name="startIndex">Starting offset to look from</param>
        /// <param name="length">Amount of entries to look through</param>
        /// <returns>Index the pattern occurrs at; if not found, returns -1.</returns>
        public static int IndexOfBytes(byte[] array, byte[] pattern, int startIndex = 0, int length = -1)
        {
            int len = pattern.Length;
            int endIndex = length > 0
                ? startIndex + length
                : array.Length - len - startIndex;

            endIndex = Math.Min(array.Length - pattern.Length, endIndex);

            int i = startIndex;
            int j = 0;
            while (true)
            {
                if (pattern[j] != array[i + j])
                {
                    if (++i == endIndex)
                        return -1;
                    j = 0;
                }
                else if (++j == len)
                {
                    return i;
                }
            }
        }

        /// <summary>
        /// Finds a provided <see cref="pattern"/> within the supplied <see cref="array"/>.
        /// </summary>
        /// <param name="array">Array to look in</param>
        /// <param name="pattern">Pattern to look for</param>
        /// <param name="wildCard">Wildcard byte to be ignored, incrementally as bitflags.</param>
        /// <param name="startIndex">Starting offset to look from</param>
        /// <param name="length">Amount of entries to look through</param>
        /// <returns>Index the pattern occurrs at; if not found, returns -1.</returns>
        public static int IndexOfPattern(byte[] array, byte[] pattern, ulong wildCard, int startIndex = 0, int length = -1)
        {
            Debug.Assert(pattern.Length <= 8*sizeof(ulong));

            int len = pattern.Length;
            int endIndex = length > 0
                ? startIndex + length
                : array.Length - len - startIndex;

            endIndex = Math.Min(array.Length - pattern.Length, endIndex);

            int i = startIndex;
            int j = 0;
            while (true)
            {
                if (pattern[j] != array[i + j] && ((wildCard >> j) & 1) == 0)
                {
                    if (++i == endIndex)
                        return -1;
                    j = 0;
                }
                else if (++j == len)
                {
                    return i;
                }
            }
        }

        /// <summary>
        /// <see cref="GameVersion.GG"/> byte pattern which precedes the TMHM list. This list is the tail end of item IDs for each TM(01->100).
        /// </summary>
        public static readonly byte[] TMHM_GG =
        {
            0xA0, 0x01, 0xA1, 0x01, 0xA2, 0x01, 0xA3, 0x01,
            0x6A, 0x02, 0x6B, 0x02, 0x6C, 0x02, 0xB2, 0x02,
            0xB3, 0x02, 0xB4, 0x02, 0xB5, 0x02, 0xB6, 0x02,
        };
    }
}