metaforce/Runtime/CGameAllocator.cpp

#include "CGameAllocator.hpp"

namespace urde
{
logvisor::Module AllocLog("urde::CGameAllocator");

std::vector<CGameAllocator::SAllocationDescription> CGameAllocator::m_allocations;

u8* CGameAllocator::Alloc(size_t len)
{
    size_t roundedLen = ROUND_UP_64(len + sizeof(SChunkDescription));
    for (SAllocationDescription& alloc : m_allocations)
    {
        /* We need to supply enough room for allocation information */
        if (alloc.freeOffset + roundedLen < alloc.allocSize)
        {
            u8* ptr = alloc.memptr.get() + alloc.freeOffset;
            SChunkDescription* chunkInfo = reinterpret_cast<SChunkDescription*>(ptr);
            *chunkInfo = SChunkDescription();
            chunkInfo->parent = &alloc;
            chunkInfo->len = len;
            alloc.freeOffset += roundedLen;
            return ptr + sizeof(SChunkDescription);
        }
    }

    /* 1MiB minimum allocation to prevent constantly allocating small amounts of memory */
    size_t allocSz = len;
    if (allocSz < (1 * 1024 * 1024 * 1024))
        allocSz = 1 * 1024 * 1024 * 1024;

    /* Pad size to allow for allocation information */
    allocSz = ROUND_UP_64(allocSz + sizeof(SChunkDescription));
    m_allocations.emplace_back();
    m_allocations.back().memptr.reset(new u8[allocSz]);
    u8* ptr = m_allocations.back().memptr.get();
    m_allocations.back().allocSize = allocSz;
    m_allocations.back().freeOffset += roundedLen;
    SChunkDescription* chunkInfo = reinterpret_cast<SChunkDescription*>(ptr);
    *chunkInfo = SChunkDescription();
    chunkInfo->parent = &m_allocations.back();
    chunkInfo->len = len;
    return ptr + sizeof(SChunkDescription);
}

void CGameAllocator::Free(u8* ptr)
{
    SChunkDescription* info = reinterpret_cast<SChunkDescription*>(ptr - sizeof(SChunkDescription));
    if (info->magic != 0xE8E8E8E8 || info->sentinal != 0xEFEFEFEF)
    {
        AllocLog.report(logvisor::Fatal, _S("Invalid chunk description, memory corruption!"));
        return;
    }

    SAllocationDescription& alloc = *info->parent;
    size_t roundedLen = ROUND_UP_32(info->len + sizeof(SChunkDescription));
    alloc.freeOffset -= roundedLen;
    /* Invalidate chunk allocation descriptor */
    memset(info, 0, ROUND_UP_64(info->len + sizeof(SChunkDescription)));
}
}