ImfXdr.h

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//
// SPDX-License-Identifier: BSD-3-Clause
// Copyright (c) Contributors to the OpenEXR Project.
//

#ifndef INCLUDED_IMF_XDR_H
#define INCLUDED_IMF_XDR_H

//----------------------------------------------------------------------------
//
//      Xdr -- routines to convert data between the machine's native
//      format and a machine-independent external data representation:
//
//          write<R> (T &o, S v);       converts a value, v, of type S
//                                      into a machine-independent
//                                      representation and stores the
//                                      result in an output buffer, o.
//
//          read<R> (T &i, S &v);       reads the machine-independent
//                                      representation of a value of type
//                                      S from input buffer i, converts
//                                      the value into the machine's native
//                                      representation, and stores the result
//                                      in v.
//
//          size<S>();                  returns the size, in bytes, of the
//                                      machine-independent representation
//                                      of an object of type S.
//
//      The write() and read() routines are templates; data can be written
//      to and read from any output or input buffer type T for which a helper
//      class, R, exits.  Class R must define a method to store a char array
//      in a T, and a method to read a char array from a T:
//
//          struct R
//          {
//              static void
//              writeChars (T &o, const char c[/*n*/], int n)
//              {
//                  ... // Write c[0], c[1] ... c[n-1] to output buffer o.
//              }
//
//              static void
//              readChars (T &i, char c[/*n*/], int n)
//              {
//                  ... // Read n characters from input buffer i
//                      // and copy them to c[0], c[1] ... c[n-1].
//              }
//          };
//
//      Example - writing to and reading from iostreams:
//
//          struct CharStreamIO
//          {
//              static void
//              writeChars (ostream &os, const char c[], int n)
//              {
//                  os.write (c, n);
//              }
//
//              static void
//              readChars (istream &is, char c[], int n)
//              {
//                  is.read (c, n);
//              }
//          };
//
//          ...
//
//          Xdr::write<CharStreamIO> (os, 3);
//          Xdr::write<CharStreamIO> (os, 5.0);
//
//----------------------------------------------------------------------------

#include "ImfNamespace.h"

#include "IexMathExc.h"
#include <cstdint>
#include <half.h>
#include <limits.h>

OPENEXR_IMF_INTERNAL_NAMESPACE_HEADER_ENTER

namespace Xdr
{

//-------------------------------
// Write data to an output stream
//-------------------------------

template <class S, class T> void write (T& out, bool v);

template <class S, class T> void write (T& out, char v);

template <class S, class T> void write (T& out, signed char v);

template <class S, class T> void write (T& out, unsigned char v);

template <class S, class T> void write (T& out, signed short v);

template <class S, class T> void write (T& out, unsigned short v);

template <class S, class T> void write (T& out, signed int v);

template <class S, class T> void write (T& out, unsigned int v);

template <class S, class T> void write (T& out, int64_t v);

template <class S, class T> void write (T& out, uint64_t v);

template <class S, class T> void write (T& out, float v);

template <class S, class T> void write (T& out, double v);

template <class S, class T> void write (T& out, half v);

template <class S, class T>
void write (T& out, const char v[/*n*/], int n); // fixed-size char array

template <class S, class T>
void write (T& out, const char v[]); // zero-terminated string

//-----------------------------------------
// Append padding bytes to an output stream
//-----------------------------------------

template <class S, class T> void pad (T& out, int n); // write n padding bytes

//-------------------------------
// Read data from an input stream
//-------------------------------

template <class S, class T> void read (T& in, bool& v);

template <class S, class T> void read (T& in, char& v);

template <class S, class T> void read (T& in, signed char& v);

template <class S, class T> void read (T& in, unsigned char& v);

template <class S, class T> void read (T& in, signed short& v);

template <class S, class T> void read (T& in, unsigned short& v);

template <class S, class T> void read (T& in, signed int& v);

template <class S, class T> void read (T& in, unsigned int& v);

template <class S, class T> void read (T& in, int64_t& v);

template <class S, class T> void read (T& in, uint64_t& v);

template <class S, class T> void read (T& in, float& v);

template <class S, class T> void read (T& in, double& v);

template <class S, class T> void read (T& in, half& v);

template <class S, class T>
void read (T& in, char v[/*n*/], int n); // fixed-size char array

template <class S, class T>
void read (T& in, int n, char v[/*n*/]); // zero-terminated string

//-------------------------------------------
// Skip over padding bytes in an input stream
//-------------------------------------------

template <class S, class T> void skip (T& in, int n); // skip n padding bytes

//--------------------------------------
// Size of the machine-independent
// representation of an object of type S
//--------------------------------------

template <class S> int size ();

//---------------
// Implementation
//---------------

template <class S, class T>
inline void
writeSignedChars (T& out, const signed char c[], int n)
{
    S::writeChars (out, (const char*) c, n);
}

template <class S, class T>
inline void
writeUnsignedChars (T& out, const unsigned char c[], int n)
{
    S::writeChars (out, (const char*) c, n);
}

template <class S, class T>
inline void
readSignedChars (T& in, signed char c[], int n)
{
    S::readChars (in, (char*) c, n);
}

template <class S, class T>
inline void
readUnsignedChars (T& in, unsigned char c[], int n)
{
    S::readChars (in, (char*) c, n);
}

template <class S, class T>
inline void
write (T& out, bool v)
{
    char c = !!v;
    S::writeChars (out, &c, 1);
}

template <class S, class T>
inline void
write (T& out, char v)
{
    S::writeChars (out, &v, 1);
}

template <class S, class T>
inline void
write (T& out, signed char v)
{
    writeSignedChars<S> (out, &v, 1);
}

template <class S, class T>
inline void
write (T& out, unsigned char v)
{
    writeUnsignedChars<S> (out, &v, 1);
}

template <class S, class T>
void
write (T& out, signed short v)
{
    signed char b[2];

    b[0] = (signed char) (v);
    b[1] = (signed char) (v >> 8);

    writeSignedChars<S> (out, b, 2);
}

template <class S, class T>
void
write (T& out, unsigned short v)
{
    unsigned char b[2];

    b[0] = (unsigned char) (v);
    b[1] = (unsigned char) (v >> 8);

    writeUnsignedChars<S> (out, b, 2);
}

template <class S, class T>
void
write (T& out, signed int v)
{
    signed char b[4];

    b[0] = (signed char) (v);
    b[1] = (signed char) (v >> 8);
    b[2] = (signed char) (v >> 16);
    b[3] = (signed char) (v >> 24);

    writeSignedChars<S> (out, b, 4);
}

template <class S, class T>
void
write (T& out, unsigned int v)
{
    unsigned char b[4];

    b[0] = (unsigned char) (v);
    b[1] = (unsigned char) (v >> 8);
    b[2] = (unsigned char) (v >> 16);
    b[3] = (unsigned char) (v >> 24);

    writeUnsignedChars<S> (out, b, 4);
}

template <class S, class T>
void
write (T& out, int64_t v)
{
    signed char b[8];

    b[0] = (signed char) (v);
    b[1] = (signed char) (v >> 8);
    b[2] = (signed char) (v >> 16);
    b[3] = (signed char) (v >> 24);
    b[4] = (signed char) (v >> 32);
    b[5] = (signed char) (v >> 40);
    b[6] = (signed char) (v >> 48);
    b[7] = (signed char) (v >> 56);

    writeSignedChars<S> (out, b, 8);
}

template <class S, class T>
void
write (T& out, uint64_t v)
{
    unsigned char b[8];

    b[0] = (unsigned char) (v);
    b[1] = (unsigned char) (v >> 8);
    b[2] = (unsigned char) (v >> 16);
    b[3] = (unsigned char) (v >> 24);
    b[4] = (unsigned char) (v >> 32);
    b[5] = (unsigned char) (v >> 40);
    b[6] = (unsigned char) (v >> 48);
    b[7] = (unsigned char) (v >> 56);

    writeUnsignedChars<S> (out, b, 8);
}

template <class S, class T>
void
write (T& out, float v)
{
    union
    {
        unsigned int i;
        float        f;
    } u;
    u.f = v;

    unsigned char b[4];

    b[0] = (unsigned char) (u.i);
    b[1] = (unsigned char) (u.i >> 8);
    b[2] = (unsigned char) (u.i >> 16);
    b[3] = (unsigned char) (u.i >> 24);

    writeUnsignedChars<S> (out, b, 4);
}

template <class S, class T>
void
write (T& out, double v)
{
    union
    {
        uint64_t i;
        double   d;
    } u;
    u.d = v;

    unsigned char b[8];

    b[0] = (unsigned char) (u.i);
    b[1] = (unsigned char) (u.i >> 8);
    b[2] = (unsigned char) (u.i >> 16);
    b[3] = (unsigned char) (u.i >> 24);
    b[4] = (unsigned char) (u.i >> 32);
    b[5] = (unsigned char) (u.i >> 40);
    b[6] = (unsigned char) (u.i >> 48);
    b[7] = (unsigned char) (u.i >> 56);

    writeUnsignedChars<S> (out, b, 8);
}

template <class S, class T>
inline void
write (T& out, half v)
{
    unsigned char b[2];

    b[0] = (unsigned char) (v.bits ());
    b[1] = (unsigned char) (v.bits () >> 8);

    writeUnsignedChars<S> (out, b, 2);
}

template <class S, class T>
inline void
write (T& out, const char v[], int n) // fixed-size char array
{
    S::writeChars (out, v, n);
}

template <class S, class T>
void
write (T& out, const char v[]) // zero-terminated string
{
    while (*v)
    {
        S::writeChars (out, v, 1);
        ++v;
    }

    S::writeChars (out, v, 1);
}

template <class S, class T>
void
pad (T& out, int n) // add n padding bytes
{
    for (int i = 0; i < n; i++)
    {
        const char c = 0;
        S::writeChars (out, &c, 1);
    }
}

template <class S, class T>
inline void
read (T& in, bool& v)
{
    char c;

    S::readChars (in, &c, 1);
    v = !!c;
}

template <class S, class T>
inline void
read (T& in, char& v)
{
    S::readChars (in, &v, 1);
}

template <class S, class T>
inline void
read (T& in, signed char& v)
{
    readSignedChars<S> (in, &v, 1);
}

template <class S, class T>
inline void
read (T& in, unsigned char& v)
{
    readUnsignedChars<S> (in, &v, 1);
}

template <class S, class T>
void
read (T& in, signed short& v)
{
    signed char b[2];

    readSignedChars<S> (in, b, 2);

    v = (static_cast<unsigned char> (b[0]) & 0x00ff) |
        (static_cast<unsigned char> (b[1]) << 8);
}

template <class S, class T>
void
read (T& in, unsigned short& v)
{
    unsigned char b[2];

    readUnsignedChars<S> (in, b, 2);

    v = (b[0] & 0x00ff) | (b[1] << 8);
}

template <class S, class T>
void
read (T& in, signed int& v)
{
    signed char b[4];

    readSignedChars<S> (in, b, 4);

    v = (static_cast<unsigned char> (b[0]) & 0x000000ff) |
        ((static_cast<unsigned char> (b[1]) << 8) & 0x0000ff00) |
        ((static_cast<unsigned char> (b[2]) << 16) & 0x00ff0000) |
        (static_cast<unsigned char> (b[3]) << 24);
}

template <class S, class T>
void
read (T& in, unsigned int& v)
{
    unsigned char b[4];

    readUnsignedChars<S> (in, b, 4);

    v = (b[0] & 0x000000ff) | ((b[1] << 8) & 0x0000ff00) |
        ((b[2] << 16) & 0x00ff0000) | (b[3] << 24);
}

template <class S, class T>
void
read (T& in, int64_t& v)
{
    signed char b[8];

    readSignedChars<S> (in, b, 8);

    v = (static_cast<int64_t> (b[0]) & 0x00000000000000ff) |
        ((static_cast<int64_t> (b[1]) << 8) & 0x000000000000ff00) |
        ((static_cast<int64_t> (b[2]) << 16) & 0x0000000000ff0000) |
        ((static_cast<int64_t> (b[3]) << 24) & 0x00000000ff000000) |
        ((static_cast<int64_t> (b[4]) << 32) & 0x000000ff00000000) |
        ((static_cast<int64_t> (b[5]) << 40) & 0x0000ff0000000000) |
        ((static_cast<int64_t> (b[6]) << 48) & 0x00ff000000000000) |
        (static_cast<int64_t> (b[7]) << 56);
}

template <class S, class T>
void
read (T& in, uint64_t& v)
{
    unsigned char b[8];

    readUnsignedChars<S> (in, b, 8);

    v = ((uint64_t) b[0] & 0x00000000000000ffLL) |
        (((uint64_t) b[1] << 8) & 0x000000000000ff00LL) |
        (((uint64_t) b[2] << 16) & 0x0000000000ff0000LL) |
        (((uint64_t) b[3] << 24) & 0x00000000ff000000LL) |
        (((uint64_t) b[4] << 32) & 0x000000ff00000000LL) |
        (((uint64_t) b[5] << 40) & 0x0000ff0000000000LL) |
        (((uint64_t) b[6] << 48) & 0x00ff000000000000LL) |
        ((uint64_t) b[7] << 56);
}

template <class S, class T>
void
read (T& in, float& v)
{
    unsigned char b[4];

    readUnsignedChars<S> (in, b, 4);

    union
    {
        unsigned int i;
        float        f;
    } u;

    u.i = (b[0] & 0x000000ff) | ((b[1] << 8) & 0x0000ff00) |
          ((b[2] << 16) & 0x00ff0000) | (b[3] << 24);

    v = u.f;
}

template <class S, class T>
void
read (T& in, double& v)
{
    unsigned char b[8];

    readUnsignedChars<S> (in, b, 8);

    union
    {
        uint64_t i;
        double   d;
    } u;

    u.i = ((uint64_t) b[0] & 0x00000000000000ffULL) |
          (((uint64_t) b[1] << 8) & 0x000000000000ff00ULL) |
          (((uint64_t) b[2] << 16) & 0x0000000000ff0000ULL) |
          (((uint64_t) b[3] << 24) & 0x00000000ff000000ULL) |
          (((uint64_t) b[4] << 32) & 0x000000ff00000000ULL) |
          (((uint64_t) b[5] << 40) & 0x0000ff0000000000ULL) |
          (((uint64_t) b[6] << 48) & 0x00ff000000000000ULL) |
          ((uint64_t) b[7] << 56);

    v = u.d;
}

template <class S, class T>
inline void
read (T& in, half& v)
{
    unsigned char b[2];

    readUnsignedChars<S> (in, b, 2);

    v.setBits ((b[0] & 0x00ff) | (b[1] << 8));
}

template <class S, class T>
inline void
read (T& in, char v[], int n) // fixed-size char array
{
    S::readChars (in, v, n);
}

template <class S, class T>
void
read (T& in, int n, char v[]) // zero-terminated string
{
    while (n >= 0)
    {
        S::readChars (in, v, 1);

        if (*v == 0) break;

        --n;
        ++v;
    }
}

template <class S, class T>
void
skip (T& in, int n) // skip n padding bytes
{
    char c[1024];

    while (n >= (int) sizeof (c))
    {
        if (!S::readChars (in, c, sizeof (c))) return;

        n -= sizeof (c);
    }

    if (n >= 1) S::readChars (in, c, n);
}

template <>
inline int
size<bool> ()
{
    return 1;
}
template <>
inline int
size<char> ()
{
    return 1;
}
template <>
inline int
size<signed char> ()
{
    return 1;
}
template <>
inline int
size<unsigned char> ()
{
    return 1;
}
template <>
inline int
size<signed short> ()
{
    return 2;
}
template <>
inline int
size<unsigned short> ()
{
    return 2;
}
template <>
inline int
size<signed int> ()
{
    return 4;
}
template <>
inline int
size<unsigned int> ()
{
    return 4;
}
template <>
inline int
size<signed long> ()
{
    return 8;
}
template <>
inline int
size<unsigned long> ()
{
    return 8;
}
template <>
inline int
size<unsigned long long> ()
{
    return 8;
}
template <>
inline int
size<float> ()
{
    return 4;
}
template <>
inline int
size<double> ()
{
    return 8;
}
template <>
inline int
size<half> ()
{
    return 2;
}

} // namespace Xdr
OPENEXR_IMF_INTERNAL_NAMESPACE_HEADER_EXIT

#if defined(OPENEXR_IMF_INTERNAL_NAMESPACE_AUTO_EXPOSE)
namespace Imf
{
using namespace OPENEXR_IMF_INTERNAL_NAMESPACE;
}
#endif

#endif