/*

 * 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 "encoding.h"

#include <math.h>

#include "internal/encoders.h"

size_t cbor_encode_uint8(uint8_t value, unsigned char* buffer,

                         size_t buffer_size) {

  return _cbor_encode_uint8(value, buffer, buffer_size, 0x00);

}

size_t cbor_encode_uint16(uint16_t value, unsigned char* buffer,

                          size_t buffer_size) {

  return _cbor_encode_uint16(value, buffer, buffer_size, 0x00);

}

size_t cbor_encode_uint32(uint32_t value, unsigned char* buffer,

                          size_t buffer_size) {

  return _cbor_encode_uint32(value, buffer, buffer_size, 0x00);

}

size_t cbor_encode_uint64(uint64_t value, unsigned char* buffer,

                          size_t buffer_size) {

  return _cbor_encode_uint64(value, buffer, buffer_size, 0x00);

}

size_t cbor_encode_uint(uint64_t value, unsigned char* buffer,

                        size_t buffer_size) {

  return _cbor_encode_uint(value, buffer, buffer_size, 0x00);

}

size_t cbor_encode_negint8(uint8_t value, unsigned char* buffer,

                           size_t buffer_size) {

  return _cbor_encode_uint8(value, buffer, buffer_size, 0x20);

}

size_t cbor_encode_negint16(uint16_t value, unsigned char* buffer,

                            size_t buffer_size) {

  return _cbor_encode_uint16(value, buffer, buffer_size, 0x20);

}

size_t cbor_encode_negint32(uint32_t value, unsigned char* buffer,

                            size_t buffer_size) {

  return _cbor_encode_uint32(value, buffer, buffer_size, 0x20);

}

size_t cbor_encode_negint64(uint64_t value, unsigned char* buffer,

                            size_t buffer_size) {

  return _cbor_encode_uint64(value, buffer, buffer_size, 0x20);

}

size_t cbor_encode_negint(uint64_t value, unsigned char* buffer,

                          size_t buffer_size) {

  return _cbor_encode_uint(value, buffer, buffer_size, 0x20);

}

size_t cbor_encode_bytestring_start(size_t length, unsigned char* buffer,

                                    size_t buffer_size) {

  return _cbor_encode_uint((size_t)length, buffer, buffer_size, 0x40);

}

size_t _cbor_encode_byte(uint8_t value, unsigned char* buffer,

                         size_t buffer_size) {

  if (buffer_size >= 1) {

    buffer[0] = value;

    return 1;

  } else

    return 0;

}

size_t cbor_encode_indef_bytestring_start(unsigned char* buffer,

                                          size_t buffer_size) {

  return _cbor_encode_byte(0x5F, buffer, buffer_size);

}

size_t cbor_encode_string_start(size_t length, unsigned char* buffer,

                                size_t buffer_size) {

  return _cbor_encode_uint((size_t)length, buffer, buffer_size, 0x60);

}

size_t cbor_encode_indef_string_start(unsigned char* buffer,

                                      size_t buffer_size) {

  return _cbor_encode_byte(0x7F, buffer, buffer_size);

}

size_t cbor_encode_array_start(size_t length, unsigned char* buffer,

                               size_t buffer_size) {

  return _cbor_encode_uint((size_t)length, buffer, buffer_size, 0x80);

}

size_t cbor_encode_indef_array_start(unsigned char* buffer,

                                     size_t buffer_size) {

  return _cbor_encode_byte(0x9F, buffer, buffer_size);

}

size_t cbor_encode_map_start(size_t length, unsigned char* buffer,

                             size_t buffer_size) {

  return _cbor_encode_uint((size_t)length, buffer, buffer_size, 0xA0);

}

size_t cbor_encode_indef_map_start(unsigned char* buffer, size_t buffer_size) {

  return _cbor_encode_byte(0xBF, buffer, buffer_size);

}

size_t cbor_encode_tag(uint64_t value, unsigned char* buffer,

                       size_t buffer_size) {

  return _cbor_encode_uint(value, buffer, buffer_size, 0xC0);

}

size_t cbor_encode_bool(bool value, unsigned char* buffer, size_t buffer_size) {

  return value ? _cbor_encode_byte(0xF5, buffer, buffer_size)

               : _cbor_encode_byte(0xF4, buffer, buffer_size);

}

size_t cbor_encode_null(unsigned char* buffer, size_t buffer_size) {

  return _cbor_encode_byte(0xF6, buffer, buffer_size);

}

size_t cbor_encode_undef(unsigned char* buffer, size_t buffer_size) {

  return _cbor_encode_byte(0xF7, buffer, buffer_size);

}

size_t cbor_encode_half(float value, unsigned char* buffer,

                        size_t buffer_size) {

  // TODO: Broken on systems that do not use IEEE 754

  /* Assuming value is normalized */

  uint32_t val = ((union _cbor_float_helper){.as_float = value}).as_uint;

  uint16_t res;

  uint8_t exp = (uint8_t)((val & 0x7F800000u) >>

                          23u); /* 0b0111_1111_1000_0000_0000_0000_0000_0000 */

  uint32_t mant =

      val & 0x7FFFFFu; /* 0b0000_0000_0111_1111_1111_1111_1111_1111 */

  if (exp == 0xFF) {   /* Infinity or NaNs */

    if (isnan(value)) {

      // Note: Values of signaling NaNs are discarded. See `cbor_encode_single`.

      res = (uint16_t)0x007e00;

    } else {

      // If the mantissa is non-zero, we have a NaN, but those are handled

      // above. See

      // https://en.wikipedia.org/wiki/Half-precision_floating-point_format

      CBOR_ASSERT(mant == 0u);

      res = (uint16_t)((val & 0x80000000u) >> 16u | 0x7C00u);

    }

  } else if (exp == 0x00) { /* Zeroes or subnorms */

    res = (uint16_t)((val & 0x80000000u) >> 16u | mant >> 13u);

  } else { /* Normal numbers */

    int8_t logical_exp = (int8_t)(exp - 127);

    CBOR_ASSERT(logical_exp == exp - 127);

    // Now we know that 2^exp <= 0 logically

    if (logical_exp < -24) {

      /* No unambiguous representation exists, this float is not a half float

         and is too small to be represented using a half, round off to zero.

         Consistent with the reference implementation. */

      res = 0;

    } else if (logical_exp < -14) {

      /* Offset the remaining decimal places by shifting the significand, the

         value is lost. This is an implementation decision that works around the

         absence of standard half-float in the language. */

      res = (uint16_t)((val & 0x80000000u) >> 16u) |  // Extract sign bit

            ((uint16_t)(1u << (24u + logical_exp)) +

             (uint16_t)(((mant >> (-logical_exp - 2)) + 1) >>

                        1));  // Round half away from zero for simplicity

    } else {

      res = (uint16_t)((val & 0x80000000u) >> 16u |

                       ((((uint8_t)logical_exp) + 15u) << 10u) |

                       (uint16_t)(mant >> 13u));

    }

  }

  return _cbor_encode_uint16(res, buffer, buffer_size, 0xE0);

}

size_t cbor_encode_single(float value, unsigned char* buffer,

                          size_t buffer_size) {

  // Note: Values of signaling NaNs are discarded. There is no standard

  // way to extract it without assumptions about the internal float

  // representation.

  if (isnan(value)) {

    return _cbor_encode_uint32(0x7FC0 << 16, buffer, buffer_size, 0xE0);

  }

  // TODO: Broken on systems that do not use IEEE 754

  return _cbor_encode_uint32(

      ((union _cbor_float_helper){.as_float = value}).as_uint, buffer,

      buffer_size, 0xE0);

}

size_t cbor_encode_double(double value, unsigned char* buffer,

                          size_t buffer_size) {

  // Note: Values of signaling NaNs are discarded. See `cbor_encode_single`.

  if (isnan(value)) {

    return _cbor_encode_uint64((uint64_t)0x7FF8 << 48, buffer, buffer_size,

                               0xE0);

  }

  // TODO: Broken on systems that do not use IEEE 754

  return _cbor_encode_uint64(

      ((union _cbor_double_helper){.as_double = value}).as_uint, buffer,

      buffer_size, 0xE0);

}

size_t cbor_encode_break(unsigned char* buffer, size_t buffer_size) {

  return _cbor_encode_byte(0xFF, buffer, buffer_size);

}

size_t cbor_encode_ctrl(uint8_t value, unsigned char* buffer,

                        size_t buffer_size) {

  return _cbor_encode_uint8(value, buffer, buffer_size, 0xE0);

}