xref: /openbsd-src/lib/libcbor/src/cbor/internal/encoders.c (revision 4dcc46c4d04180142eda526ce521dfb137776d05)

/*
 * 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 "encoders.h"
#include <string.h>

size_t _cbor_encode_uint8(uint8_t value, unsigned char *buffer,
                          size_t buffer_size, uint8_t offset) {
  if (value <= 23) {
    if (buffer_size >= 1) {
      buffer[0] = value + offset;
      return 1;
    }
  } else {
    if (buffer_size >= 2) {
      buffer[0] = 0x18 + offset;
      buffer[1] = value;
      return 2;
    }
  }
  return 0;
}

size_t _cbor_encode_uint16(uint16_t value, unsigned char *buffer,
                           size_t buffer_size, uint8_t offset) {
  if (buffer_size >= 3) {
    buffer[0] = 0x19 + offset;

#ifdef IS_BIG_ENDIAN
    memcpy(buffer + 1, &value, 2);
#else
    buffer[1] = (unsigned char)(value >> 8);
    buffer[2] = (unsigned char)value;
#endif

    return 3;
  } else
    return 0;
}

size_t _cbor_encode_uint32(uint32_t value, unsigned char *buffer,
                           size_t buffer_size, uint8_t offset) {
  if (buffer_size >= 5) {
    buffer[0] = 0x1A + offset;

#ifdef IS_BIG_ENDIAN
    memcpy(buffer + 1, &value, 4);
#else
    buffer[1] = (unsigned char)(value >> 24);
    buffer[2] = (unsigned char)(value >> 16);
    buffer[3] = (unsigned char)(value >> 8);
    buffer[4] = (unsigned char)value;
#endif

    return 5;
  } else
    return 0;
}

size_t _cbor_encode_uint64(uint64_t value, unsigned char *buffer,
                           size_t buffer_size, uint8_t offset) {
  if (buffer_size >= 9) {
    buffer[0] = 0x1B + offset;

#ifdef IS_BIG_ENDIAN
    memcpy(buffer + 1, &value, 8);
#else
    buffer[1] = (unsigned char)(value >> 56);
    buffer[2] = (unsigned char)(value >> 48);
    buffer[3] = (unsigned char)(value >> 40);
    buffer[4] = (unsigned char)(value >> 32);
    buffer[5] = (unsigned char)(value >> 24);
    buffer[6] = (unsigned char)(value >> 16);
    buffer[7] = (unsigned char)(value >> 8);
    buffer[8] = (unsigned char)value;
#endif

    return 9;
  } else
    return 0;
}

size_t _cbor_encode_uint(uint64_t value, unsigned char *buffer,
                         size_t buffer_size, uint8_t offset) {
  if (value <= UINT16_MAX)
    if (value <= UINT8_MAX)
      return _cbor_encode_uint8((uint8_t)value, buffer, buffer_size, offset);
    else
      return _cbor_encode_uint16((uint16_t)value, buffer, buffer_size, offset);
  else if (value <= UINT32_MAX)
    return _cbor_encode_uint32((uint32_t)value, buffer, buffer_size, offset);
  else
    return _cbor_encode_uint64((uint64_t)value, buffer, buffer_size, offset);
}