Streaming Encoding

cbor/encoding.h exposes a low-level encoding API to encode CBOR objects on the fly. Unlike cbor_serialize(), these functions take logical values (integers, floats, strings, etc.) instead of cbor_item_t. The client is responsible for constructing the compound types correctly (e.g. terminating arrays).

Streaming encoding is typically used to create a streaming (indefinite length) CBOR byte strings, strings, arrays, and maps. Complete example: examples/streaming_array.c

size_t cbor_encode_uint8(uint8_t value, unsigned char *buffer, size_t buffer_size)

size_t cbor_encode_uint16(uint16_t value, unsigned char *buffer, size_t buffer_size)

size_t cbor_encode_uint32(uint32_t value, unsigned char *buffer, size_t buffer_size)

size_t cbor_encode_uint64(uint64_t value, unsigned char *buffer, size_t buffer_size)

size_t cbor_encode_uint(uint64_t value, unsigned char *buffer, size_t buffer_size)

size_t cbor_encode_negint8(uint8_t value, unsigned char *buffer, size_t buffer_size)

size_t cbor_encode_negint16(uint16_t value, unsigned char *buffer, size_t buffer_size)

size_t cbor_encode_negint32(uint32_t value, unsigned char *buffer, size_t buffer_size)

size_t cbor_encode_negint64(uint64_t value, unsigned char *buffer, size_t buffer_size)

size_t cbor_encode_negint(uint64_t value, unsigned char *buffer, size_t buffer_size)

size_t cbor_encode_bytestring_start(size_t length, unsigned char *buffer, size_t buffer_size)

size_t cbor_encode_indef_bytestring_start(unsigned char *buffer, size_t buffer_size)

size_t cbor_encode_string_start(size_t length, unsigned char *buffer, size_t buffer_size)

size_t cbor_encode_indef_string_start(unsigned char *buffer, size_t buffer_size)

size_t cbor_encode_array_start(size_t length, unsigned char *buffer, size_t buffer_size)

size_t cbor_encode_indef_array_start(unsigned char *buffer, size_t buffer_size)

size_t cbor_encode_map_start(size_t length, unsigned char *buffer, size_t buffer_size)

size_t cbor_encode_indef_map_start(unsigned char *buffer, size_t buffer_size)

size_t cbor_encode_tag(uint64_t value, unsigned char *buffer, size_t buffer_size)

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

size_t cbor_encode_null(unsigned char *buffer, size_t buffer_size)

size_t cbor_encode_undef(unsigned char *buffer, size_t buffer_size)

size_t cbor_encode_half(float value, unsigned char *buffer, size_t buffer_size)

Encodes a half-precision float.

Since there is no native representation or semantics for half floats in the language, we use single-precision floats, as every value that can be expressed as a half-float can also be expressed as a float.

This however means that not all floats passed to this function can be unambiguously encoded. The behavior is as follows:

• Infinity, NaN are preserved

• Zero is preserved

• Denormalized numbers keep their sign bit and 10 most significant bit of the significand

• All other numbers

  • If the logical value of the exponent is < -24, the output is zero

  • If the logical value of the exponent is between -23 and -14, the output is cut off to represent the ‘magnitude’ of the input, by which we mean (-1)^{signbit} x 1.0e{exponent}. The value in the significand is lost.

  • In all other cases, the sign bit, the exponent, and 10 most significant bits of the significand are kept

Note: Signaling NaNs are encoded as a standard, “quiet” NaN.

size_t cbor_encode_single(float value, unsigned char *buffer, size_t buffer_size)

Encodes a single precision float.

Note: Signaling NaNs are encoded as a standard, “quiet” NaN.

size_t cbor_encode_double(double value, unsigned char *buffer, size_t buffer_size)

Encodes a double precision float.

Note: Signaling NaNs are encoded as a standard, “quiet” NaN.

size_t cbor_encode_break(unsigned char *buffer, size_t buffer_size)

size_t cbor_encode_ctrl(uint8_t value, unsigned char *buffer, size_t buffer_size)