AuroraRuntime/Source/Compression/AuCompression.cpp

/***
    Copyright (C) 2021 J Reece Wilson (a/k/a "Reece"). All rights reserved.

    File: AuCompression.cpp
    Date: 2021-6-17
    Author: Reece
***/
#include <Source/RuntimeInternal.hpp>
#include "AuCompression.hpp"

#include "zstd.h"

namespace Aurora::Compression
{
    AUKN_SYM bool Compress(const AuMemoryViewRead &source, AuByteBuffer &out, int iCompressionLevel /* -7 to 22 */)
    {
        if (!out.GetOrAllocateLinearWriteable(source.length))
        {
            SysPushErrorMemory();
            return {};
        }

        auto uRet = ::ZSTD_compress(out.writePtr, source.length, source.ptr, source.length, iCompressionLevel);
        if (::ZSTD_isError(uRet))
        {
            return false;
        }

        out.writePtr += uRet;

        if (!out.flagCircular &&
            out.flagExpandable)
        {
            if (!AuTryDownsize(out, out.writePtr - out.base))
            {
                SysPushErrorMemory();
                return false;
            }
        }

        return true;
    }
    
    AUKN_SYM bool Decompress(const AuMemoryViewRead &source, AuByteBuffer &out)
    {
        AuUInt32 dwRead = 0;

        while (dwRead != source.length)
        {
            auto pBlockPointer   = reinterpret_cast<const AuUInt8 *>(source.ptr) + dwRead;
            auto uDeflatedLength = ZSTD_findFrameCompressedSize(pBlockPointer, source.length - dwRead);
            auto uInflatedLength = ZSTD_getFrameContentSize(pBlockPointer, source.length - dwRead);

            if (uDeflatedLength == ZSTD_CONTENTSIZE_ERROR)
            {
                return false;
            }

            if (uInflatedLength == ZSTD_CONTENTSIZE_UNKNOWN)
            {
                return false;
            }

            if (::ZSTD_isError(uInflatedLength))
            {
                return false;
            }
            
            if (!out.GetOrAllocateLinearWriteable(uInflatedLength))
            {
                SysPushErrorMemory();
                return false;
            }

            auto uRet = ::ZSTD_decompress(out.writePtr, uInflatedLength, source.ptr, source.length);
            if (::ZSTD_isError(uRet))
            {
                return false;
            }

            out.writePtr += uRet;

            dwRead += AuUInt32(uDeflatedLength);
        }

        return true;
    }
}