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This commit is contained in:
Petteri Aimonen
2013-03-02 16:27:31 +02:00
parent 0e3053894f
commit f8a143fdfe
3 changed files with 35 additions and 35 deletions
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36
docs/reference.rst
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@@ -37,22 +37,23 @@ pb_type_t
---------
Defines the encoder/decoder behaviour that should be used for a field. ::
typedef enum { ... } pb_type_t;
typedef uint8_t pb_type_t;
The low-order byte of the enumeration values defines the function that can be used for encoding and decoding the field data:
The low-order nibble of the enumeration values defines the function that can be used for encoding and decoding the field data:
==================== ===== ================================================
LTYPE identifier Value Storage format
==================== ===== ================================================
PB_LTYPE_VARINT 0x00 Integer.
PB_LTYPE_SVARINT 0x01 Integer, zigzag encoded.
PB_LTYPE_FIXED 0x02 Integer or floating point.
PB_LTYPE_BYTES 0x03 Structure with *size_t* field and byte array.
PB_LTYPE_STRING 0x04 Null-terminated string.
PB_LTYPE_SUBMESSAGE 0x05 Submessage structure.
PB_LTYPE_FIXED32 0x02 32-bit integer or floating point.
PB_LTYPE_FIXED64 0x03 64-bit integer or floating point.
PB_LTYPE_BYTES 0x04 Structure with *size_t* field and byte array.
PB_LTYPE_STRING 0x05 Null-terminated string.
PB_LTYPE_SUBMESSAGE 0x06 Submessage structure.
==================== ===== ================================================
The high-order byte defines whether the field is required, optional, repeated or callback:
The bits 4-5 define whether the field is required, optional or repeated:
==================== ===== ================================================
HTYPE identifier Value Field handling
@@ -60,13 +61,24 @@ HTYPE identifier Value Field handling
PB_HTYPE_REQUIRED 0x00 Verify that field exists in decoded message.
PB_HTYPE_OPTIONAL 0x10 Use separate *has_<field>* boolean to specify
whether the field is present.
PB_HTYPE_ARRAY 0x20 A repeated field with preallocated array.
(Unless it is a callback)
PB_HTYPE_REPEATED 0x20 A repeated field with preallocated array.
Separate *<field>_count* for number of items.
PB_HTYPE_CALLBACK 0x30 A field with dynamic storage size, data is
actually a pointer to a structure containing a
callback function.
(Unless it is a callback)
==================== ===== ================================================
The bits 6-7 define the how the storage for the field is allocated:
==================== ===== ================================================
ATYPE identifier Value Allocation method
==================== ===== ================================================
PB_ATYPE_STATIC 0x00 Statically allocated storage in the structure.
PB_ATYPE_CALLBACK 0x40 A field with dynamic storage size. Struct field
actually contains a pointer to a callback
function.
==================== ===== ================================================
pb_field_t
----------
Describes a single structure field with memory position in relation to others. The descriptions are usually autogenerated. ::
@@ -83,7 +95,7 @@ Describes a single structure field with memory position in relation to others. T
} pb_packed;
:tag: Tag number of the field or 0 to terminate a list of fields.
:type: LTYPE and HTYPE of the field.
:type: LTYPE, HTYPE and ATYPE of the field.
:data_offset: Offset of field data, relative to the end of the previous field.
:size_offset: Offset of *bool* flag for optional fields or *size_t* count for arrays, relative to field data.
:data_size: Size of a single data entry, in bytes. For PB_LTYPE_BYTES, the size of the byte array inside the containing structure. For PB_HTYPE_CALLBACK, size of the C data type if known.