From 35c8bc4c5807af41a37cc901dcbbfee7ab73f7bf Mon Sep 17 00:00:00 2001 From: "madmaxoft@gmail.com" Date: Mon, 7 May 2012 20:22:04 +0000 Subject: Fast NBT Parser (loading a chunk is now about 10 times faster) git-svn-id: http://mc-server.googlecode.com/svn/trunk@481 0a769ca7-a7f5-676a-18bf-c427514a06d6 --- source/FastNBT.cpp | 320 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 320 insertions(+) create mode 100644 source/FastNBT.cpp (limited to 'source/FastNBT.cpp') diff --git a/source/FastNBT.cpp b/source/FastNBT.cpp new file mode 100644 index 000000000..fa3edec52 --- /dev/null +++ b/source/FastNBT.cpp @@ -0,0 +1,320 @@ + +// FastNBT.cpp + +// Implements the fast NBT parser and writer + +#include "Globals.h" +#include "FastNBT.h" + + + + + +#define RETURN_FALSE_IF_FALSE(X) do { if (!X) return false; } while (0) + + + + + +/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// +// cFastNBTParser: + +#define NEEDBYTES(N) \ + if (m_Length - m_Pos < N) \ + { \ + return false; \ + } + + + + + +cParsedNBT::cParsedNBT(const char * a_Data, int a_Length) : + m_Data(a_Data), + m_Length(a_Length), + m_Pos(0) +{ + m_IsValid = Parse(); +} + + + + + +bool cParsedNBT::Parse(void) +{ + if (m_Length < 3) + { + // Data too short + return false; + } + if (m_Data[0] != TAG_Compound) + { + // The top-level tag must be a Compound + return false; + } + + m_Tags.reserve(200); + + m_Tags.push_back(cFastNBTTag(TAG_Compound, -1)); + + m_Pos = 1; + + RETURN_FALSE_IF_FALSE(ReadString(m_Tags.back().m_NameStart, m_Tags.back().m_NameLength)); + RETURN_FALSE_IF_FALSE(ReadCompound()); + + return true; +} + + + + + +bool cParsedNBT::ReadString(int & a_StringStart, int & a_StringLen) +{ + NEEDBYTES(2); + a_StringStart = m_Pos + 2; + a_StringLen = ntohs(*((short *)(m_Data + m_Pos))); + if (a_StringLen < 0) + { + // Invalid string length + return false; + } + m_Pos += 2 + a_StringLen; + return true; +} + + + + + +bool cParsedNBT::ReadCompound(void) +{ + // Reads the latest tag as a compound + int ParentIdx = m_Tags.size() - 1; + int PrevSibling = -1; + while (true) + { + NEEDBYTES(1); + eTagType TagType = (eTagType)(m_Data[m_Pos]); + m_Pos++; + if (TagType == TAG_End) + { + break; + } + m_Tags.push_back(cFastNBTTag(TagType, ParentIdx, PrevSibling)); + if (PrevSibling >= 0) + { + m_Tags[PrevSibling].m_NextSibling = m_Tags.size() - 1; + } + else + { + m_Tags[ParentIdx].m_FirstChild = m_Tags.size() - 1; + } + PrevSibling = m_Tags.size() - 1; + RETURN_FALSE_IF_FALSE(ReadString(m_Tags.back().m_NameStart, m_Tags.back().m_NameLength)); + RETURN_FALSE_IF_FALSE(ReadTag()); + } // while (true) + m_Tags[ParentIdx].m_LastChild = PrevSibling; + return true; +} + + + + + +bool cParsedNBT::ReadList(eTagType a_ChildrenType) +{ + // Reads the latest tag as a list of items of type a_ChildrenType + + // Read the count: + NEEDBYTES(4); + int Count = ntohl(*((int *)(m_Data + m_Pos))); + m_Pos += 4; + if (Count < 0) + { + return false; + } + + // Read items: + int ParentIdx = m_Tags.size() - 1; + int PrevSibling = -1; + for (int i = 0; i < Count; i++) + { + m_Tags.push_back(cFastNBTTag(a_ChildrenType, ParentIdx, PrevSibling)); + if (PrevSibling >= 0) + { + m_Tags[PrevSibling].m_NextSibling = m_Tags.size() - 1; + } + else + { + m_Tags[ParentIdx].m_FirstChild = m_Tags.size() - 1; + } + PrevSibling = m_Tags.size() - 1; + RETURN_FALSE_IF_FALSE(ReadTag()); + } // for (i) + m_Tags[ParentIdx].m_LastChild = PrevSibling; + return true; +} + + + + + +#define CASE_SIMPLE_TAG(TAGTYPE, LEN) \ + case TAG_##TAGTYPE: \ + { \ + NEEDBYTES(LEN); \ + Tag.m_DataStart = m_Pos; \ + Tag.m_DataLength = LEN; \ + m_Pos += LEN; \ + return true; \ + } + +bool cParsedNBT::ReadTag(void) +{ + cFastNBTTag & Tag = m_Tags.back(); + switch (Tag.m_Type) + { + CASE_SIMPLE_TAG(Byte, 1) + CASE_SIMPLE_TAG(Short, 2) + CASE_SIMPLE_TAG(Int, 4) + CASE_SIMPLE_TAG(Long, 8) + CASE_SIMPLE_TAG(Float, 4) + CASE_SIMPLE_TAG(Double, 8) + + case TAG_String: + { + return ReadString(Tag.m_DataStart, Tag.m_DataLength); + } + + case TAG_ByteArray: + { + NEEDBYTES(4); + int len = ntohl(*((int *)(m_Data + m_Pos))); + m_Pos += 4; + if (len < 0) + { + // Invalid length + return false; + } + NEEDBYTES(len); + Tag.m_DataLength = len; + Tag.m_DataStart = m_Pos; + m_Pos += len; + return true; + } + + case TAG_List: + { + NEEDBYTES(1); + eTagType ItemType = (eTagType)m_Data[m_Pos]; + m_Pos++; + RETURN_FALSE_IF_FALSE(ReadList(ItemType)); + return true; + } + + case TAG_Compound: + { + RETURN_FALSE_IF_FALSE(ReadCompound()); + return true; + } + + case TAG_IntArray: + { + NEEDBYTES(4); + int len = ntohl(*((int *)(m_Data + m_Pos))); + m_Pos += 4; + if (len < 0) + { + // Invalid length + return false; + } + len *= 4; + NEEDBYTES(len); + Tag.m_DataLength = len; + Tag.m_DataStart = m_Pos; + m_Pos += len; + return true; + } + + default: + { + ASSERT(!"Unhandled NBT tag type"); + return false; + } + } // switch (iType) +} + +#undef CASE_SIMPLE_TAG + + + + + +int cParsedNBT::FindChildByName(int a_Tag, const char * a_Name, size_t a_NameLength) const +{ + if (a_Tag < 0) + { + return -1; + } + if (m_Tags[a_Tag].m_Type != TAG_Compound) + { + return -1; + } + + if (a_NameLength == 0) + { + a_NameLength = strlen(a_Name); + } + for (int Child = m_Tags[a_Tag].m_FirstChild; Child != -1; Child = m_Tags[Child].m_NextSibling) + { + if ( + (m_Tags[Child].m_NameLength == a_NameLength) && + (memcmp(m_Data + m_Tags[Child].m_NameStart, a_Name, a_NameLength) == 0) + ) + { + return Child; + } + } // for Child - children of a_Tag + return -1; +} + + + + + +int cParsedNBT::FindTagByPath(int a_Tag, const AString & a_Path) const +{ + if (a_Tag < 0) + { + return -1; + } + size_t Begin = 0; + size_t Length = a_Path.length(); + int Tag = a_Tag; + for (size_t i = 0; i < Length; i++) + { + if (a_Path[i] != '\\') + { + continue; + } + Tag = FindChildByName(Tag, a_Path.c_str() + Begin, i - Begin - 1); + if (Tag < 0) + { + return -1; + } + Begin = i + 1; + } // for i - a_Path[] + + if (Begin < Length) + { + Tag = FindChildByName(Tag, a_Path.c_str() + Begin, Length - Begin); + } + return Tag; +} + + + + + -- cgit v1.2.3