/*

 * Copyright (c) 2014-2020 Pavel Kalvoda <me@pavelkalvoda.com>

 *

 * libcbor is free software; you can redistribute it and/or modify

 * it under the terms of the MIT license. See LICENSE for details.

 */

#include "loaders.h"

#include <math.h>

#include <string.h>

uint8_t _cbor_load_uint8(cbor_data source) { return (uint8_t)*source; }

uint16_t _cbor_load_uint16(const unsigned char *source) {

#ifdef IS_BIG_ENDIAN

  uint16_t result;

  memcpy(&result, source, 2);

  return result;

#else

  return ((uint16_t) * (source + 0) << 8) + (uint8_t) * (source + 1);

#endif

}

uint32_t _cbor_load_uint32(const unsigned char *source) {

#ifdef IS_BIG_ENDIAN

  uint32_t result;

  memcpy(&result, source, 4);

  return result;

#else

  return ((uint32_t) * (source + 0) << 0x18) +

         ((uint32_t) * (source + 1) << 0x10) +

         ((uint16_t) * (source + 2) << 0x08) + (uint8_t) * (source + 3);

#endif

}

uint64_t _cbor_load_uint64(const unsigned char *source) {

#ifdef IS_BIG_ENDIAN

  uint64_t result;

  memcpy(&result, source, 8);

  return result;

#else

  return ((uint64_t) * (source + 0) << 0x38) +

         ((uint64_t) * (source + 1) << 0x30) +

         ((uint64_t) * (source + 2) << 0x28) +

         ((uint64_t) * (source + 3) << 0x20) +

         ((uint32_t) * (source + 4) << 0x18) +

         ((uint32_t) * (source + 5) << 0x10) +

         ((uint16_t) * (source + 6) << 0x08) + (uint8_t) * (source + 7);

#endif

}

/* As per https://www.rfc-editor.org/rfc/rfc8949.html#name-half-precision */

float _cbor_decode_half(unsigned char *halfp) {

  int half = (halfp[0] << 8) + halfp[1];

  int exp = (half >> 10) & 0x1f;

  int mant = half & 0x3ff;

  double val;

  if (exp == 0)

    val = ldexp(mant, -24);

  else if (exp != 31)

    val = ldexp(mant + 1024, exp - 25);

  else

    val = mant == 0 ? INFINITY : NAN;

  return (float)(half & 0x8000 ? -val : val);

}

float _cbor_load_half(cbor_data source) {

  /* Discard const */

  return _cbor_decode_half((unsigned char *)source);

}

float _cbor_load_float(cbor_data source) {

  union _cbor_float_helper helper = {.as_uint = _cbor_load_uint32(source)};

  return helper.as_float;

}

double _cbor_load_double(cbor_data source) {

  union _cbor_double_helper helper = {.as_uint = _cbor_load_uint64(source)};

  return helper.as_double;

}