lib/utils/loadstor.h

/*
* Load/Store Operators
* (C) 1999-2007,2015,2017 Jack Lloyd
*     2007 Yves Jerschow
*
* Botan is released under the Simplified BSD License (see license.txt)
*/

#ifndef BOTAN_LOAD_STORE_H_
#define BOTAN_LOAD_STORE_H_

#include <botan/types.h>
#include <botan/bswap.h>
#include <botan/mem_ops.h>
#include <vector>

BOTAN_FUTURE_INTERNAL_HEADER(loadstor.h)

#if defined(BOTAN_TARGET_CPU_IS_BIG_ENDIAN)
   #define BOTAN_ENDIAN_N2L(x) reverse_bytes(x)
   #define BOTAN_ENDIAN_L2N(x) reverse_bytes(x)
   #define BOTAN_ENDIAN_N2B(x) (x)
   #define BOTAN_ENDIAN_B2N(x) (x)

#elif defined(BOTAN_TARGET_CPU_IS_LITTLE_ENDIAN)
   #define BOTAN_ENDIAN_N2L(x) (x)
   #define BOTAN_ENDIAN_L2N(x) (x)
   #define BOTAN_ENDIAN_N2B(x) reverse_bytes(x)
   #define BOTAN_ENDIAN_B2N(x) reverse_bytes(x)

#endif

namespace Botan {

/**
* Byte extraction
* @param byte_num which byte to extract, 0 == highest byte
* @param input the value to extract from
* @return byte byte_num of input
*/
template<typename T> inline constexpr uint8_t get_byte(size_t byte_num, T input)
   {
   return static_cast<uint8_t>(
      input >> (((~byte_num)&(sizeof(T)-1)) << 3)
      );
   }

/**
* Make a uint16_t from two bytes
* @param i0 the first byte
* @param i1 the second byte
* @return i0 || i1
*/
inline constexpr uint16_t make_uint16(uint8_t i0, uint8_t i1)
   {
   return static_cast<uint16_t>((static_cast<uint16_t>(i0) << 8) | i1);
   }

/**
* Make a uint32_t from four bytes
* @param i0 the first byte
* @param i1 the second byte
* @param i2 the third byte
* @param i3 the fourth byte
* @return i0 || i1 || i2 || i3
*/
inline constexpr uint32_t make_uint32(uint8_t i0, uint8_t i1, uint8_t i2, uint8_t i3)
   {
   return ((static_cast<uint32_t>(i0) << 24) |
           (static_cast<uint32_t>(i1) << 16) |
           (static_cast<uint32_t>(i2) <<  8) |
           (static_cast<uint32_t>(i3)));
   }

/**
* Make a uint64_t from eight bytes
* @param i0 the first byte
* @param i1 the second byte
* @param i2 the third byte
* @param i3 the fourth byte
* @param i4 the fifth byte
* @param i5 the sixth byte
* @param i6 the seventh byte
* @param i7 the eighth byte
* @return i0 || i1 || i2 || i3 || i4 || i5 || i6 || i7
*/
inline constexpr uint64_t make_uint64(uint8_t i0, uint8_t i1, uint8_t i2, uint8_t i3,
                                      uint8_t i4, uint8_t i5, uint8_t i6, uint8_t i7)
    {
   return ((static_cast<uint64_t>(i0) << 56) |
           (static_cast<uint64_t>(i1) << 48) |
           (static_cast<uint64_t>(i2) << 40) |
           (static_cast<uint64_t>(i3) << 32) |
           (static_cast<uint64_t>(i4) << 24) |
           (static_cast<uint64_t>(i5) << 16) |
           (static_cast<uint64_t>(i6) <<  8) |
           (static_cast<uint64_t>(i7)));
    }

/**
* Load a big-endian word
* @param in a pointer to some bytes
* @param off an offset into the array
* @return off'th T of in, as a big-endian value
*/
template<typename T>
inline T load_be(const uint8_t in[], size_t off)
   {
   in += off * sizeof(T);
   T out = 0;
   for(size_t i = 0; i != sizeof(T); ++i)
      out = static_cast<T>((out << 8) | in[i]);
   return out;
   }

/**
* Load a little-endian word
* @param in a pointer to some bytes
* @param off an offset into the array
* @return off'th T of in, as a litte-endian value
*/
template<typename T>
inline T load_le(const uint8_t in[], size_t off)
   {
   in += off * sizeof(T);
   T out = 0;
   for(size_t i = 0; i != sizeof(T); ++i)
      out = (out << 8) | in[sizeof(T)-1-i];
   return out;
   }

/**
* Load a big-endian uint16_t
* @param in a pointer to some bytes
* @param off an offset into the array
* @return off'th uint16_t of in, as a big-endian value
*/
template<>
inline uint16_t load_be<uint16_t>(const uint8_t in[], size_t off)
   {
   in += off * sizeof(uint16_t);

#if defined(BOTAN_ENDIAN_N2B)
   uint16_t x;
   typecast_copy(x, in);
   return BOTAN_ENDIAN_N2B(x);
#else
   return make_uint16(in[0], in[1]);
#endif
   }

/**
* Load a little-endian uint16_t
* @param in a pointer to some bytes
* @param off an offset into the array
* @return off'th uint16_t of in, as a little-endian value
*/
template<>
inline uint16_t load_le<uint16_t>(const uint8_t in[], size_t off)
   {
   in += off * sizeof(uint16_t);

#if defined(BOTAN_ENDIAN_N2L)
   uint16_t x;
   typecast_copy(x, in);
   return BOTAN_ENDIAN_N2L(x);
#else
   return make_uint16(in[1], in[0]);
#endif
   }

/**
* Load a big-endian uint32_t
* @param in a pointer to some bytes
* @param off an offset into the array
* @return off'th uint32_t of in, as a big-endian value
*/
template<>
inline uint32_t load_be<uint32_t>(const uint8_t in[], size_t off)
   {
   in += off * sizeof(uint32_t);
#if defined(BOTAN_ENDIAN_N2B)
   uint32_t x;
   typecast_copy(x, in);
   return BOTAN_ENDIAN_N2B(x);
#else
   return make_uint32(in[0], in[1], in[2], in[3]);
#endif
   }

/**
* Load a little-endian uint32_t
* @param in a pointer to some bytes
* @param off an offset into the array
* @return off'th uint32_t of in, as a little-endian value
*/
template<>
inline uint32_t load_le<uint32_t>(const uint8_t in[], size_t off)
   {
   in += off * sizeof(uint32_t);
#if defined(BOTAN_ENDIAN_N2L)
   uint32_t x;
   typecast_copy(x, in);
   return BOTAN_ENDIAN_N2L(x);
#else
   return make_uint32(in[3], in[2], in[1], in[0]);
#endif
   }

/**
* Load a big-endian uint64_t
* @param in a pointer to some bytes
* @param off an offset into the array
* @return off'th uint64_t of in, as a big-endian value
*/
template<>
inline uint64_t load_be<uint64_t>(const uint8_t in[], size_t off)
   {
   in += off * sizeof(uint64_t);
#if defined(BOTAN_ENDIAN_N2B)
   uint64_t x;
   typecast_copy(x, in);
   return BOTAN_ENDIAN_N2B(x);
#else
   return make_uint64(in[0], in[1], in[2], in[3],
                      in[4], in[5], in[6], in[7]);
#endif
   }

/**
* Load a little-endian uint64_t
* @param in a pointer to some bytes
* @param off an offset into the array
* @return off'th uint64_t of in, as a little-endian value
*/
template<>
inline uint64_t load_le<uint64_t>(const uint8_t in[], size_t off)
   {
   in += off * sizeof(uint64_t);
#if defined(BOTAN_ENDIAN_N2L)
   uint64_t x;
   typecast_copy(x, in);
   return BOTAN_ENDIAN_N2L(x);
#else
   return make_uint64(in[7], in[6], in[5], in[4],
                      in[3], in[2], in[1], in[0]);
#endif
   }

/**
* Load two little-endian words
* @param in a pointer to some bytes
* @param x0 where the first word will be written
* @param x1 where the second word will be written
*/
template<typename T>
inline void load_le(const uint8_t in[], T& x0, T& x1)
   {
   x0 = load_le<T>(in, 0);
   x1 = load_le<T>(in, 1);
   }

/**
* Load four little-endian words
* @param in a pointer to some bytes
* @param x0 where the first word will be written
* @param x1 where the second word will be written
* @param x2 where the third word will be written
* @param x3 where the fourth word will be written
*/
template<typename T>
inline void load_le(const uint8_t in[],
                    T& x0, T& x1, T& x2, T& x3)
   {
   x0 = load_le<T>(in, 0);
   x1 = load_le<T>(in, 1);
   x2 = load_le<T>(in, 2);
   x3 = load_le<T>(in, 3);
   }

/**
* Load eight little-endian words
* @param in a pointer to some bytes
* @param x0 where the first word will be written
* @param x1 where the second word will be written
* @param x2 where the third word will be written
* @param x3 where the fourth word will be written
* @param x4 where the fifth word will be written
* @param x5 where the sixth word will be written
* @param x6 where the seventh word will be written
* @param x7 where the eighth word will be written
*/
template<typename T>
inline void load_le(const uint8_t in[],
                    T& x0, T& x1, T& x2, T& x3,
                    T& x4, T& x5, T& x6, T& x7)
   {
   x0 = load_le<T>(in, 0);
   x1 = load_le<T>(in, 1);
   x2 = load_le<T>(in, 2);
   x3 = load_le<T>(in, 3);
   x4 = load_le<T>(in, 4);
   x5 = load_le<T>(in, 5);
   x6 = load_le<T>(in, 6);
   x7 = load_le<T>(in, 7);
   }

/**
* Load a variable number of little-endian words
* @param out the output array of words
* @param in the input array of bytes
* @param count how many words are in in
*/
template<typename T>
inline void load_le(T out[],
                    const uint8_t in[],
                    size_t count)
   {
   if(count > 0)
      {
#if defined(BOTAN_TARGET_CPU_IS_LITTLE_ENDIAN)
      typecast_copy(out, in, count);

#elif defined(BOTAN_TARGET_CPU_IS_BIG_ENDIAN)
      typecast_copy(out, in, count);

      const size_t blocks = count - (count % 4);
      const size_t left = count - blocks;

      for(size_t i = 0; i != blocks; i += 4)
         bswap_4(out + i);

      for(size_t i = 0; i != left; ++i)
         out[blocks+i] = reverse_bytes(out[blocks+i]);
#else
      for(size_t i = 0; i != count; ++i)
         out[i] = load_le<T>(in, i);
#endif
      }
   }

/**
* Load two big-endian words
* @param in a pointer to some bytes
* @param x0 where the first word will be written
* @param x1 where the second word will be written
*/
template<typename T>
inline void load_be(const uint8_t in[], T& x0, T& x1)
   {
   x0 = load_be<T>(in, 0);
   x1 = load_be<T>(in, 1);
   }

/**
* Load four big-endian words
* @param in a pointer to some bytes
* @param x0 where the first word will be written
* @param x1 where the second word will be written
* @param x2 where the third word will be written
* @param x3 where the fourth word will be written
*/
template<typename T>
inline void load_be(const uint8_t in[],
                    T& x0, T& x1, T& x2, T& x3)
   {
   x0 = load_be<T>(in, 0);
   x1 = load_be<T>(in, 1);
   x2 = load_be<T>(in, 2);
   x3 = load_be<T>(in, 3);
   }

/**
* Load eight big-endian words
* @param in a pointer to some bytes
* @param x0 where the first word will be written
* @param x1 where the second word will be written
* @param x2 where the third word will be written
* @param x3 where the fourth word will be written
* @param x4 where the fifth word will be written
* @param x5 where the sixth word will be written
* @param x6 where the seventh word will be written
* @param x7 where the eighth word will be written
*/
template<typename T>
inline void load_be(const uint8_t in[],
                    T& x0, T& x1, T& x2, T& x3,
                    T& x4, T& x5, T& x6, T& x7)
   {
   x0 = load_be<T>(in, 0);
   x1 = load_be<T>(in, 1);
   x2 = load_be<T>(in, 2);
   x3 = load_be<T>(in, 3);
   x4 = load_be<T>(in, 4);
   x5 = load_be<T>(in, 5);
   x6 = load_be<T>(in, 6);
   x7 = load_be<T>(in, 7);
   }

/**
* Load a variable number of big-endian words
* @param out the output array of words
* @param in the input array of bytes
* @param count how many words are in in
*/
template<typename T>
inline void load_be(T out[],
                    const uint8_t in[],
                    size_t count)
   {
   if(count > 0)
      {
#if defined(BOTAN_TARGET_CPU_IS_BIG_ENDIAN)
      typecast_copy(out, in, count);

#elif defined(BOTAN_TARGET_CPU_IS_LITTLE_ENDIAN)
      typecast_copy(out, in, count);
      const size_t blocks = count - (count % 4);
      const size_t left = count - blocks;

      for(size_t i = 0; i != blocks; i += 4)
         bswap_4(out + i);

      for(size_t i = 0; i != left; ++i)
         out[blocks+i] = reverse_bytes(out[blocks+i]);
#else
      for(size_t i = 0; i != count; ++i)
         out[i] = load_be<T>(in, i);
#endif
      }
   }

/**
* Store a big-endian uint16_t
* @param in the input uint16_t
* @param out the byte array to write to
*/
inline void store_be(uint16_t in, uint8_t out[2])
   {
#if defined(BOTAN_ENDIAN_N2B)
   uint16_t o = BOTAN_ENDIAN_N2B(in);
   typecast_copy(out, o);
#else
   out[0] = get_byte(0, in);
   out[1] = get_byte(1, in);
#endif
   }

/**
* Store a little-endian uint16_t
* @param in the input uint16_t
* @param out the byte array to write to
*/
inline void store_le(uint16_t in, uint8_t out[2])
   {
#if defined(BOTAN_ENDIAN_N2L)
   uint16_t o = BOTAN_ENDIAN_N2L(in);
   typecast_copy(out, o);
#else
   out[0] = get_byte(1, in);
   out[1] = get_byte(0, in);
#endif
   }

/**
* Store a big-endian uint32_t
* @param in the input uint32_t
* @param out the byte array to write to
*/
inline void store_be(uint32_t in, uint8_t out[4])
   {
#if defined(BOTAN_ENDIAN_B2N)
   uint32_t o = BOTAN_ENDIAN_B2N(in);
   typecast_copy(out, o);
#else
   out[0] = get_byte(0, in);
   out[1] = get_byte(1, in);
   out[2] = get_byte(2, in);
   out[3] = get_byte(3, in);
#endif
   }

/**
* Store a little-endian uint32_t
* @param in the input uint32_t
* @param out the byte array to write to
*/
inline void store_le(uint32_t in, uint8_t out[4])
   {
#if defined(BOTAN_ENDIAN_L2N)
   uint32_t o = BOTAN_ENDIAN_L2N(in);
   typecast_copy(out, o);
#else
   out[0] = get_byte(3, in);
   out[1] = get_byte(2, in);
   out[2] = get_byte(1, in);
   out[3] = get_byte(0, in);
#endif
   }

/**
* Store a big-endian uint64_t
* @param in the input uint64_t
* @param out the byte array to write to
*/
inline void store_be(uint64_t in, uint8_t out[8])
   {
#if defined(BOTAN_ENDIAN_B2N)
   uint64_t o = BOTAN_ENDIAN_B2N(in);
   typecast_copy(out, o);
#else
   out[0] = get_byte(0, in);
   out[1] = get_byte(1, in);
   out[2] = get_byte(2, in);
   out[3] = get_byte(3, in);
   out[4] = get_byte(4, in);
   out[5] = get_byte(5, in);
   out[6] = get_byte(6, in);
   out[7] = get_byte(7, in);
#endif
   }

/**
* Store a little-endian uint64_t
* @param in the input uint64_t
* @param out the byte array to write to
*/
inline void store_le(uint64_t in, uint8_t out[8])
   {
#if defined(BOTAN_ENDIAN_L2N)
   uint64_t o = BOTAN_ENDIAN_L2N(in);
   typecast_copy(out, o);
#else
   out[0] = get_byte(7, in);
   out[1] = get_byte(6, in);
   out[2] = get_byte(5, in);
   out[3] = get_byte(4, in);
   out[4] = get_byte(3, in);
   out[5] = get_byte(2, in);
   out[6] = get_byte(1, in);
   out[7] = get_byte(0, in);
#endif
   }

/**
* Store two little-endian words
* @param out the output byte array
* @param x0 the first word
* @param x1 the second word
*/
template<typename T>
inline void store_le(uint8_t out[], T x0, T x1)
   {
   store_le(x0, out + (0 * sizeof(T)));
   store_le(x1, out + (1 * sizeof(T)));
   }

/**
* Store two big-endian words
* @param out the output byte array
* @param x0 the first word
* @param x1 the second word
*/
template<typename T>
inline void store_be(uint8_t out[], T x0, T x1)
   {
   store_be(x0, out + (0 * sizeof(T)));
   store_be(x1, out + (1 * sizeof(T)));
   }

/**
* Store four little-endian words
* @param out the output byte array
* @param x0 the first word
* @param x1 the second word
* @param x2 the third word
* @param x3 the fourth word
*/
template<typename T>
inline void store_le(uint8_t out[], T x0, T x1, T x2, T x3)
   {
   store_le(x0, out + (0 * sizeof(T)));
   store_le(x1, out + (1 * sizeof(T)));
   store_le(x2, out + (2 * sizeof(T)));
   store_le(x3, out + (3 * sizeof(T)));
   }

/**
* Store four big-endian words
* @param out the output byte array
* @param x0 the first word
* @param x1 the second word
* @param x2 the third word
* @param x3 the fourth word
*/
template<typename T>
inline void store_be(uint8_t out[], T x0, T x1, T x2, T x3)
   {
   store_be(x0, out + (0 * sizeof(T)));
   store_be(x1, out + (1 * sizeof(T)));
   store_be(x2, out + (2 * sizeof(T)));
   store_be(x3, out + (3 * sizeof(T)));
   }

/**
* Store eight little-endian words
* @param out the output byte array
* @param x0 the first word
* @param x1 the second word
* @param x2 the third word
* @param x3 the fourth word
* @param x4 the fifth word
* @param x5 the sixth word
* @param x6 the seventh word
* @param x7 the eighth word
*/
template<typename T>
inline void store_le(uint8_t out[], T x0, T x1, T x2, T x3,
                                 T x4, T x5, T x6, T x7)
   {
   store_le(x0, out + (0 * sizeof(T)));
   store_le(x1, out + (1 * sizeof(T)));
   store_le(x2, out + (2 * sizeof(T)));
   store_le(x3, out + (3 * sizeof(T)));
   store_le(x4, out + (4 * sizeof(T)));
   store_le(x5, out + (5 * sizeof(T)));
   store_le(x6, out + (6 * sizeof(T)));
   store_le(x7, out + (7 * sizeof(T)));
   }

/**
* Store eight big-endian words
* @param out the output byte array
* @param x0 the first word
* @param x1 the second word
* @param x2 the third word
* @param x3 the fourth word
* @param x4 the fifth word
* @param x5 the sixth word
* @param x6 the seventh word
* @param x7 the eighth word
*/
template<typename T>
inline void store_be(uint8_t out[], T x0, T x1, T x2, T x3,
                                 T x4, T x5, T x6, T x7)
   {
   store_be(x0, out + (0 * sizeof(T)));
   store_be(x1, out + (1 * sizeof(T)));
   store_be(x2, out + (2 * sizeof(T)));
   store_be(x3, out + (3 * sizeof(T)));
   store_be(x4, out + (4 * sizeof(T)));
   store_be(x5, out + (5 * sizeof(T)));
   store_be(x6, out + (6 * sizeof(T)));
   store_be(x7, out + (7 * sizeof(T)));
   }

template<typename T>
void copy_out_be(uint8_t out[], size_t out_bytes, const T in[])
   {
   while(out_bytes >= sizeof(T))
      {
      store_be(in[0], out);
      out += sizeof(T);
      out_bytes -= sizeof(T);
      in += 1;
   }

   for(size_t i = 0; i != out_bytes; ++i)
      out[i] = get_byte(i%8, in[0]);
   }

template<typename T, typename Alloc>
void copy_out_vec_be(uint8_t out[], size_t out_bytes, const std::vector<T, Alloc>& in)
   {
   copy_out_be(out, out_bytes, in.data());
   }

template<typename T>
void copy_out_le(uint8_t out[], size_t out_bytes, const T in[])
   {
   while(out_bytes >= sizeof(T))
      {
      store_le(in[0], out);
      out += sizeof(T);
      out_bytes -= sizeof(T);
      in += 1;
   }

   for(size_t i = 0; i != out_bytes; ++i)
      out[i] = get_byte(sizeof(T) - 1 - (i % 8), in[0]);
   }

template<typename T, typename Alloc>
void copy_out_vec_le(uint8_t out[], size_t out_bytes, const std::vector<T, Alloc>& in)
   {
   copy_out_le(out, out_bytes, in.data());
   }

}

#endif