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#ifndef _PB_H_
#define _PB_H_
#include <stdint.h>
#include <stddef.h> // size_t
#include <stdbool.h>
#ifdef __GNUC__
// This just reduces memory requirements, but is not required.
#define pb_packed __attribute__((packed))
#else
#define pb_packed
#endif
/* Lightweight input stream.
* If buf is NULL, read but don't store bytes.
* You have to provide a callback function for reading.
* You can use state to store your own data (e.g. buffer pointer),
* and rely on pb_read to verify that no-body reads past bytes_left.
* However, substreams may change bytes_left so don't use that to
* compute any pointers.
*/
typedef struct _pb_istream_t pb_istream_t;
struct _pb_istream_t
{
bool (*callback)(pb_istream_t *stream, uint8_t *buf, size_t count);
void *state; // Free field for use by callback implementation
size_t bytes_left;
};
static inline bool pb_read(pb_istream_t *stream, uint8_t *buf, size_t count)
{
if (stream->bytes_left < count)
return false;
bool status = stream->callback(stream, buf, count);
stream->bytes_left -= count;
return status;
}
/* Lightweight output stream. */
typedef struct _pb_ostream_t pb_ostream_t;
struct _pb_ostream_t
{
bool (*callback)(pb_ostream_t *stream, const uint8_t *buf, size_t count);
void *state; // Free field for use by callback implementation
size_t bytes_written;
};
static inline bool pb_write(pb_ostream_t *stream, const uint8_t *buf, size_t count)
{
bool status = stream->callback(stream, buf, count);
stream->bytes_written += count;
return status;
}
/* List of possible field types
* 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.
*/
typedef enum {
// Standard integer types
PB_LTYPE_UINT32 = 0x00,
PB_LTYPE_INT32 = 0x00,
PB_LTYPE_SINT32 = 0x01,
PB_LTYPE_FIXED32 = 0x02,
PB_LTYPE_SFIXED32 = 0x02,
PB_LTYPE_UINT64 = 0x03,
PB_LTYPE_INT64 = 0x03,
PB_LTYPE_SINT64 = 0x04,
PB_LTYPE_FIXED64 = 0x05,
PB_LTYPE_SFIXED64 = 0x05,
PB_LTYPE_BOOL = 0x06,
PB_LTYPE_ENUM = 0x07,
// Standard float types
PB_LTYPE_FLOAT = 0x08,
PB_LTYPE_DOUBLE = 0x09,
// Byte array with pre-allocated buffer.
// data_size is the length of the allocated PB_BYTES_ARRAY structure.
PB_LTYPE_BYTES = 0x0A,
// String with pre-allocated buffer.
// data_size is the maximum length.
PB_LTYPE_STRING = 0x0B,
// Submessage
// submsg_fields is pointer to field descriptions
PB_LTYPE_SUBMESSAGE = 0x0C,
/////////////
// Modifier flags
// Just the basic, write data at data_offset
PB_HTYPE_REQUIRED = 0x00,
// Write true at size_offset
PB_HTYPE_OPTIONAL = 0x10,
// Read to pre-allocated array
// Maximum number of entries is array_size,
// actual number is stored at size_offset
PB_HTYPE_ARRAY = 0x20,
// Works for all required/optional/repeated fields.
// data_offset points to pb_callback_t structure.
// LTYPE is ignored.
PB_HTYPE_CALLBACK = 0x30
} pb_packed pb_type_t;
#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 actual data or array start
uint8_t size_offset; // Offset of array size or has-boolean
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;
#define PB_LAST_FIELD {0,0,0,0}
// This structure is used for 'bytes' arrays.
// It has the number of bytes in the beginning, and after that an array.
#define PB_BYTES_ARRAY(buffersize) \
struct { \
size_t size; \
uint8_t bytes[buffersize]; \
}
typedef PB_BYTES_ARRAY(1) pb_bytes_array_t;
// This structure is used for giving the callback function.
//
// 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.
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, void *arg);
} funcs;
// Free arg for use by callback
void *arg;
};
#endif
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