nanopb/pb.h

#ifndef _PB_H_
#define _PB_H_

/* pb.h: Common parts for nanopb library.
 * Most of these are quite low-level stuff. For the high-level interface,
 * see pb_encode.h or pb_decode.h
 */

#include <stdint.h>
#include <stddef.h>
#include <stdbool.h>

#ifdef __GNUC__
/* This just reduces memory requirements, but is not required. */
#define pb_packed __attribute__((packed))
#else
#define pb_packed
#endif

/* List of possible field types. These are used in the autogenerated code.
 * Least-significant 4 bits tell the scalar type
 * Most-significant 4 bits specify repeated/required/packed etc.
 * 
 * INT32 and UINT32 are treated the same, as are (U)INT64 and (S)FIXED*
 * These types are simply casted to correct field type when they are
 * assigned to the memory pointer.
 * SINT* is different, though, because it is zig-zag coded.
 */

/************************
 * Field contents types *
 ************************/

typedef uint8_t pb_type_t;

/* Numeric types */
#define PB_LTYPE_VARINT 0x00 /* int32, uint32, int64, uint64, bool, enum */
#define PB_LTYPE_SVARINT 0x01 /* sint32, sint64 */
#define PB_LTYPE_FIXED32 0x02 /* fixed32, sfixed32, float */
#define PB_LTYPE_FIXED64 0x03 /* fixed64, sfixed64, double */

/* Marker for last packable field type. */
#define PB_LTYPE_LAST_PACKABLE 0x03

/* Byte array with pre-allocated buffer.
 * data_size is the length of the allocated PB_BYTES_ARRAY structure. */
#define PB_LTYPE_BYTES 0x04

/* String with pre-allocated buffer.
 * data_size is the maximum length. */
#define PB_LTYPE_STRING 0x05

/* Submessage
 * submsg_fields is pointer to field descriptions */
#define PB_LTYPE_SUBMESSAGE 0x06

/* Number of declared LTYPES */
#define PB_LTYPES_COUNT 7

/******************
 * Modifier flags *
 ******************/

/* Just the basic, write data at data_offset */
#define PB_HTYPE_REQUIRED 0x00

/* Write true at size_offset */
#define PB_HTYPE_OPTIONAL 0x10

/* Read to pre-allocated array
 * Maximum number of entries is array_size,
 * actual number is stored at size_offset */
#define PB_HTYPE_ARRAY 0x20

/* Works for all required/optional/repeated fields.
 * data_offset points to pb_callback_t structure.
 * LTYPE should be 0 (it is ignored, but sometimes
 * used to speculatively index an array). */
#define PB_HTYPE_CALLBACK 0x30

#define PB_HTYPE(x) ((x) & 0xF0)
#define PB_LTYPE(x) ((x) & 0x0F)

/* This structure is used in auto-generated constants
 * to specify struct fields.
 * You can change field sizes here if you need structures
 * larger than 256 bytes or field tags larger than 256.
 * The compiler should complain if your .proto has such
 * structures ("initializer too large for type").
 */
typedef struct _pb_field_t pb_field_t;
struct _pb_field_t {
    uint8_t tag;
    pb_type_t type;
    uint8_t data_offset; /* Offset of field data, relative to previous field. */
    int8_t size_offset; /* Offset of array size or has-boolean, relative to data */
    uint8_t data_size; /* Data size in bytes for a single item */
    uint8_t array_size; /* Maximum number of entries in array */
    
    /* Field definitions for submessage
     * OR default value for all other non-array, non-callback types
     * If null, then field will zeroed. */
    const void *ptr;
} pb_packed;

/* This structure is used for 'bytes' arrays.
 * It has the number of bytes in the beginning, and after that an array.
 * Note that actual structs used will have a different length of bytes array.
 */
typedef struct {
    size_t size;
    uint8_t bytes[1];
} pb_bytes_array_t;

/* This structure is used for giving the callback function.
 * It is stored in the message structure and filled in by the method that
 * calls pb_decode.
 *
 * The decoding callback will be given a limited-length stream
 * If the wire type was string, the length is the length of the string.
 * If the wire type was a varint/fixed32/fixed64, the length is the length
 * of the actual value.
 * The function may be called multiple times (especially for repeated types,
 * but also otherwise if the message happens to contain the field multiple
 * times.)
 *
 * The encoding callback will receive the actual output stream.
 * It should write all the data in one call, including the field tag and
 * wire type. It can write multiple fields.
 *
 * The callback can be null if you want to skip a field.
 */
typedef struct _pb_istream_t pb_istream_t;
typedef struct _pb_ostream_t pb_ostream_t;
typedef struct _pb_callback_t pb_callback_t;
struct _pb_callback_t {
    union {
        bool (*decode)(pb_istream_t *stream, const pb_field_t *field, void *arg);
        bool (*encode)(pb_ostream_t *stream, const pb_field_t *field, const void *arg);
    } funcs;
    
    /* Free arg for use by callback */
    void *arg;
};

/* Wire types. Library user needs these only in encoder callbacks. */
typedef enum {
    PB_WT_VARINT = 0,
    PB_WT_64BIT  = 1,
    PB_WT_STRING = 2,
    PB_WT_32BIT  = 5
} pb_wire_type_t;

/* These macros are used to declare pb_field_t's in the constant array. */
#define pb_membersize(st, m) (sizeof ((st*)0)->m)
#define pb_arraysize(st, m) (pb_membersize(st, m) / pb_membersize(st, m[0]))
#define pb_delta(st, m1, m2) ((int)offsetof(st, m1) - (int)offsetof(st, m2))
#define pb_delta_end(st, m1, m2) (offsetof(st, m1) - offsetof(st, m2) - pb_membersize(st, m2))
#define PB_LAST_FIELD {0,0,0,0}


#endif