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mirror of https://github.com/fadden/6502bench.git synced 2024-12-26 04:30:52 +00:00
6502bench/CommonUtil/RawData.cs
Andy McFadden df823f4c09 Add support for points in wireframe meshes
This allows rendering of a vertex directly, rather than just as an
edge endpoint.  They're currently drawn as small '+' signs.  A
round dot would be better, but the code is passing a list of line
segments around, so this is simpler.
2020-04-11 11:23:16 -07:00

102 lines
4.2 KiB
C#

/*
* Copyright 2018 faddenSoft
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
using System;
using System.Diagnostics;
namespace CommonUtil {
public class RawData {
/// <summary>
/// Extracts an integer from the data stream. Integers less than 4 bytes wide
/// are not sign-extended.
/// </summary>
/// <param name="data">Raw data stream.</param>
/// <param name="offset">Start offset.</param>
/// <param name="width">Word width, which may be 1-4 bytes.</param>
/// <param name="isBigEndian">True if word is in big-endian order.</param>
/// <returns>Value found.</returns>
public static int GetWord(byte[] data, int offset, int width, bool isBigEndian) {
if (width < 1 || width > 4 || offset + width > data.Length) {
throw new ArgumentOutOfRangeException("GetWord(offset=" + offset + " width=" +
width + "), data.Length=" + data.Length);
}
if (isBigEndian) {
switch (width) {
case 1:
return data[offset];
case 2:
return (data[offset] << 8) | data[offset + 1];
case 3:
return (data[offset] << 16) | (data[offset + 1] << 8) | data[offset + 2];
case 4:
return (data[offset] << 24) | (data[offset + 1] << 16) |
(data[offset + 2] << 8) | data[offset + 3];
}
} else {
switch (width) {
case 1:
return data[offset];
case 2:
return data[offset] | (data[offset + 1] << 8);
case 3:
return data[offset] | (data[offset + 1] << 8) | (data[offset + 2] << 16);
case 4:
return data[offset] | (data[offset + 1] << 8) | (data[offset + 2] << 16) |
data[offset + 3] << 24;
}
}
throw new Exception("GetWord(): should not be here");
}
/// <summary>
/// Fetches a two-byte little-endian value from a byte stream, advancing the offset.
/// </summary>
/// <param name="data">Byte stream.</param>
/// <param name="offset">Initial offset. Value will be incremented by 2.</param>
/// <returns>Value fetched.</returns>
public static ushort FetchLittleUshort(byte[] data, ref int offset) {
ushort val = (ushort)(data[offset] | (data[offset + 1] << 8));
offset += 2;
return val;
}
/// <summary>
/// Compare parts of two arrays for equality.
/// </summary>
/// <remarks>
/// We can do this faster with unsafe code. For byte arrays, see
/// https://stackoverflow.com/q/43289/294248 .
/// </remarks>
/// <param name="ar1">First array.</param>
/// <param name="offset1">Initial offset in first array.</param>
/// <param name="ar2">Second array.</param>
/// <param name="offset2">Initial offset in second array.</param>
/// <param name="count">Number of elements to compare.</param>
/// <returns>True if the array elements are equal.</returns>
public static bool CompareArrays<T>(T[] ar1, int offset1, T[] ar2, int offset2,
int count) {
Debug.Assert(count > 0);
for (int i = 0; i < count; i++) {
if (!ar1[offset1 + i].Equals(ar2[offset2 + i])) {
return false;
}
}
return true;
}
}
}