openmw/components/nif/nifstream.hpp

///Functions used to read raw binary data from .nif files

#ifndef OPENMW_COMPONENTS_NIF_NIFSTREAM_HPP
#define OPENMW_COMPONENTS_NIF_NIFSTREAM_HPP

#include <cassert>
#include <stdint.h>
#include <stdexcept>
#include <vector>

#include <components/files/constrainedfilestream.hpp>

#include <osg/Vec3f>
#include <osg/Vec4f>
#include <osg/Quat>

#include "niftypes.hpp"

namespace Nif
{

class NIFFile;

/* 
    readLittleEndianBufferOfType: This template should only be used with non POD data types
*/
template <uint32_t numInstances, typename T, typename IntegerT> inline void readLittleEndianBufferOfType(Files::IStreamPtr &pIStream, T* dest)
{
#if defined(__x86_64__) || defined(_M_X64) || defined(__i386) || defined(_M_IX86)
    pIStream->read((char*)dest, numInstances * sizeof(T));
#else
    uint8_t* destByteBuffer = (uint8_t*)dest;
    pIStream->read((char*)dest, numInstances * sizeof(T));
    /*
        Due to the loop iterations being known at compile time,
        this nested loop will most likely be unrolled
        For example, for 2 instances of a 4 byte data type, you should get the below result
    */
    union {
        IntegerT i;
        T t;
    } u;
    for (uint32_t i = 0; i < numInstances; i++)
    {
        u = { 0 };
        for (uint32_t byte = 0; byte < sizeof(T); byte++)
            u.i |= (((IntegerT)destByteBuffer[i * sizeof(T) + byte]) << (byte * 8));
        dest[i] = u.t;
    }
#endif
}

/*
    readLittleEndianDynamicBufferOfType: This template should only be used with non POD data types
*/
template <typename T, typename IntegerT> inline void readLittleEndianDynamicBufferOfType(Files::IStreamPtr &pIStream, T* dest, uint32_t numInstances)
{
#if defined(__x86_64__) || defined(_M_X64) || defined(__i386) || defined(_M_IX86)
    pIStream->read((char*)dest, numInstances * sizeof(T));
#else
    uint8_t* destByteBuffer = (uint8_t*)dest;
    pIStream->read((char*)dest, numInstances * sizeof(T));
    union {
        IntegerT i;
        T t;
    } u;
    for (uint32_t i = 0; i < numInstances; i++)
    {
        u.i = 0;
        for (uint32_t byte = 0; byte < sizeof(T); byte++)
            u.i |= ((IntegerT)destByteBuffer[i * sizeof(T) + byte]) << (byte * 8);
        dest[i] = u.t;
    }
#endif
}
template<typename type, typename IntegerT> type inline readLittleEndianType(Files::IStreamPtr &pIStream)
{
    type val;
    readLittleEndianBufferOfType<1,type,IntegerT>(pIStream, (type*)&val);
    return val;
}

class NIFStream
{
    /// Input stream
    Files::IStreamPtr inp;

public:

    NIFFile * const file;

    NIFStream (NIFFile * file, Files::IStreamPtr inp): inp (inp), file (file) {}

    void skip(size_t size) { inp->ignore(size); }

    char getChar()
    {
        return readLittleEndianType<char,char>(inp);
    }

    short getShort()
    {
        return readLittleEndianType<short,short>(inp);
    }

    unsigned short getUShort()
    {
        return readLittleEndianType<unsigned short,unsigned short>(inp);
    }

    int getInt()
    {
        return readLittleEndianType<int,int>(inp);
    }

    unsigned int getUInt()
    {
        return readLittleEndianType<unsigned int,unsigned int>(inp);
    }

    float getFloat()
    {
        return readLittleEndianType<float,uint32_t>(inp);
    }

    osg::Vec2f getVector2()
    {
        osg::Vec2f vec;
        readLittleEndianBufferOfType<2,float,uint32_t>(inp, (float*)&vec._v[0]);
        return vec;
    }

    osg::Vec3f getVector3()
    {
        osg::Vec3f vec;
        readLittleEndianBufferOfType<3, float,uint32_t>(inp, (float*)&vec._v[0]);
        return vec;
    }

    osg::Vec4f getVector4()
    {
        osg::Vec4f vec;
        readLittleEndianBufferOfType<4, float,uint32_t>(inp, (float*)&vec._v[0]);
        return vec;
    }

    Matrix3 getMatrix3()
    {
        Matrix3 mat;
        readLittleEndianBufferOfType<9, float,uint32_t>(inp, (float*)&mat.mValues);
        return mat;
    }

    osg::Quat getQuaternion();

    Transformation getTrafo();

    ///Read in a string of the given length
    std::string getString(size_t length)
    {
        std::vector<char> str(length + 1, 0);

        inp->read(&str[0], length);

        return &str[0];
    }
    ///Read in a string of the length specified in the file
    std::string getString()
    {
        size_t size = readLittleEndianType<uint32_t,uint32_t>(inp);
        return getString(size);
    }
    ///This is special since the version string doesn't start with a number, and ends with "\n"
    std::string getVersionString()
    {
        std::string result;
        std::getline(*inp, result);
        return result;
    }

    void getUShorts(std::vector<unsigned short> &vec, size_t size)
    {
        vec.resize(size);
        readLittleEndianDynamicBufferOfType<unsigned short,unsigned short>(inp, &vec.front(), size);
    }

    void getFloats(std::vector<float> &vec, size_t size)
    {
        vec.resize(size);
        readLittleEndianDynamicBufferOfType<float,uint32_t>(inp, &vec.front(), size);
    }

    void getVector2s(std::vector<osg::Vec2f> &vec, size_t size)
    {
        vec.resize(size);
        /* The packed storage of each Vec2f is 2 floats exactly */
        readLittleEndianDynamicBufferOfType<float,uint32_t>(inp,(float*) &vec.front(), size*2);
    }

    void getVector3s(std::vector<osg::Vec3f> &vec, size_t size)
    {
        vec.resize(size);
        /* The packed storage of each Vec3f is 3 floats exactly */
        readLittleEndianDynamicBufferOfType<float,uint32_t>(inp, (float*) &vec.front(), size*3);
    }

    void getVector4s(std::vector<osg::Vec4f> &vec, size_t size)
    {
        vec.resize(size);
        /* The packed storage of each Vec4f is 4 floats exactly */
        readLittleEndianDynamicBufferOfType<float,uint32_t>(inp, (float*) &vec.front(), size*4);
    }

    void getQuaternions(std::vector<osg::Quat> &quat, size_t size)
    {
        quat.resize(size);
        for (size_t i = 0;i < quat.size();i++)
            quat[i] = getQuaternion();
    }
};

}

#endif