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Eliminate allocation in AsciiHexDecodeFilter

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Jason Nelson 2024-04-01 22:29:07 -07:00 committed by BobLd
parent d85ea4f95d
commit b498f5a076
1 changed files with 30 additions and 33 deletions
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63
src/UglyToad.PdfPig/Filters/AsciiHexDecodeFilter.cs
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@ -1,7 +1,7 @@
namespace UglyToad.PdfPig.Filters namespace UglyToad.PdfPig.Filters
{ {
using System; using System;
using System.IO; using Core;
using Tokens; using Tokens;
/// <inheritdoc /> /// <inheritdoc />
@ -34,48 +34,45 @@
Span<byte> pair = stackalloc byte[2]; Span<byte> pair = stackalloc byte[2];
var index = 0; var index = 0;
using (var memoryStream = new MemoryStream()) using var writer = new ArrayPoolBufferWriter<byte>(input.Length);
using (var binaryWriter = new BinaryWriter(memoryStream))
for (var i = 0; i < input.Length; i++)
{ {
for (var i = 0; i < input.Length; i++) if (input[i] == '>')
{ {
if (input[i] == '>') break;
{
break;
}
if (IsWhitespace(input[i]) || input[i] == '<')
{
continue;
}
pair[index] = input[i];
index++;
if (index == 2)
{
WriteHexToByte(pair, binaryWriter);
index = 0;
}
} }
if (index > 0) if (IsWhitespace(input[i]) || input[i] == '<')
{ {
if (index == 1) continue;
{
pair[1] = (byte) '0';
}
WriteHexToByte(pair, binaryWriter);
} }
binaryWriter.Flush(); pair[index] = input[i];
return memoryStream.ToArray(); index++;
if (index == 2)
{
WriteHexToByte(pair, writer);
index = 0;
}
} }
if (index > 0)
{
if (index == 1)
{
pair[1] = (byte)'0';
}
WriteHexToByte(pair, writer);
}
return writer.WrittenSpan.ToArray();
} }
private static void WriteHexToByte(ReadOnlySpan<byte> hexBytes, BinaryWriter writer) private static void WriteHexToByte(ReadOnlySpan<byte> hexBytes, ArrayPoolBufferWriter<byte> writer)
{ {
var first = ReverseHex[hexBytes[0]]; var first = ReverseHex[hexBytes[0]];
var second = ReverseHex[hexBytes[1]]; var second = ReverseHex[hexBytes[1]];