1 /* pb_encode.c -- encode a protobuf using minimal resources
3 * 2011 Petteri Aimonen <jpa@kapsi.fi>
6 #define NANOPB_INTERNALS
11 /* The warn_unused_result attribute appeared first in gcc-3.4.0 */
12 #if !defined(__GNUC__) || ( __GNUC__ < 3) || (__GNUC__ == 3 && __GNUC_MINOR__ < 4)
15 /* Verify that we remember to check all return values for proper error propagation */
16 #define checkreturn __attribute__((warn_unused_result))
19 typedef bool (*pb_encoder_t)(pb_ostream_t *stream, const pb_field_t *field, const void *src) checkreturn;
21 /* --- Function pointers to field encoders ---
22 * Order in the array must match pb_action_t LTYPE numbering.
24 static const pb_encoder_t PB_ENCODERS[PB_LTYPES_COUNT] = {
35 /* pb_ostream_t implementation */
37 static bool checkreturn buf_write(pb_ostream_t *stream, const uint8_t *buf, size_t count)
39 uint8_t *dest = (uint8_t*)stream->state;
40 stream->state = dest + count;
48 pb_ostream_t pb_ostream_from_buffer(uint8_t *buf, size_t bufsize)
52 stream.callback = (void*)1; /* Just some marker value */
54 stream.callback = &buf_write;
57 stream.max_size = bufsize;
58 stream.bytes_written = 0;
62 bool checkreturn pb_write(pb_ostream_t *stream, const uint8_t *buf, size_t count)
64 if (stream->callback != NULL)
66 if (stream->bytes_written + count > stream->max_size)
70 if (!buf_write(stream, buf, count))
73 if (!stream->callback(stream, buf, count))
78 stream->bytes_written += count;
82 /* Main encoding stuff */
84 /* Callbacks don't need this function because they usually know the data type
85 * without examining the field structure.
86 * Therefore it is static for now.
88 static bool checkreturn encode_array(pb_ostream_t *stream, const pb_field_t *field,
89 const void *pData, size_t count, pb_encoder_t func)
98 if (PB_LTYPE(field->type) <= PB_LTYPE_LAST_PACKABLE)
100 if (!pb_encode_tag(stream, PB_WT_STRING, field->tag))
103 /* Determine the total size of packed array. */
104 if (PB_LTYPE(field->type) == PB_LTYPE_FIXED32)
108 else if (PB_LTYPE(field->type) == PB_LTYPE_FIXED64)
114 pb_ostream_t sizestream = {0,0,0,0};
116 for (i = 0; i < count; i++)
118 if (!func(&sizestream, field, p))
120 p = (const char*)p + field->data_size;
122 size = sizestream.bytes_written;
125 if (!pb_encode_varint(stream, (uint64_t)size))
128 if (stream->callback == NULL)
129 return pb_write(stream, NULL, size); /* Just sizing.. */
133 for (i = 0; i < count; i++)
135 if (!func(stream, field, p))
137 p = (const char*)p + field->data_size;
143 for (i = 0; i < count; i++)
145 if (!pb_encode_tag_for_field(stream, field))
147 if (!func(stream, field, p))
149 p = (const char*)p + field->data_size;
156 bool checkreturn encode_static_field(pb_ostream_t *stream, const pb_field_t *field, const void *pData)
161 func = PB_ENCODERS[PB_LTYPE(field->type)];
162 pSize = (const char*)pData + field->size_offset;
164 switch (PB_HTYPE(field->type))
166 case PB_HTYPE_REQUIRED:
167 if (!pb_encode_tag_for_field(stream, field))
169 if (!func(stream, field, pData))
173 case PB_HTYPE_OPTIONAL:
174 if (*(const bool*)pSize)
176 if (!pb_encode_tag_for_field(stream, field))
179 if (!func(stream, field, pData))
184 case PB_HTYPE_REPEATED:
185 if (!encode_array(stream, field, pData, *(const size_t*)pSize, func))
196 bool checkreturn encode_callback_field(pb_ostream_t *stream, const pb_field_t *field, const void *pData)
198 const pb_callback_t *callback = (const pb_callback_t*)pData;
199 if (callback->funcs.encode != NULL)
201 if (!callback->funcs.encode(stream, field, callback->arg))
207 bool checkreturn pb_encode(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
209 const pb_field_t *field = fields;
210 const void *pData = src_struct;
211 size_t prev_size = 0;
213 while (field->tag != 0)
215 pData = (const char*)pData + prev_size + field->data_offset;
216 prev_size = field->data_size;
218 /* Special case for static arrays */
219 if (PB_ATYPE(field->type) == PB_ATYPE_STATIC &&
220 PB_HTYPE(field->type) == PB_HTYPE_REPEATED)
222 prev_size *= field->array_size;
225 switch (PB_ATYPE(field->type))
227 case PB_ATYPE_STATIC:
228 if (!encode_static_field(stream, field, pData))
232 case PB_ATYPE_CALLBACK:
233 if (!encode_callback_field(stream, field, pData))
247 /* Helper functions */
248 bool checkreturn pb_encode_varint(pb_ostream_t *stream, uint64_t value)
254 return pb_write(stream, (uint8_t*)&value, 1);
258 buffer[i] = (uint8_t)((value & 0x7F) | 0x80);
262 buffer[i-1] &= 0x7F; /* Unset top bit on last byte */
264 return pb_write(stream, buffer, i);
267 bool checkreturn pb_encode_svarint(pb_ostream_t *stream, int64_t value)
271 zigzagged = (uint64_t)(~(value << 1));
273 zigzagged = (uint64_t)(value << 1);
275 return pb_encode_varint(stream, zigzagged);
278 bool checkreturn pb_encode_fixed32(pb_ostream_t *stream, const void *value)
280 #ifdef __BIG_ENDIAN__
281 const uint8_t *bytes = value;
283 lebytes[0] = bytes[3];
284 lebytes[1] = bytes[2];
285 lebytes[2] = bytes[1];
286 lebytes[3] = bytes[0];
287 return pb_write(stream, lebytes, 4);
289 return pb_write(stream, (const uint8_t*)value, 4);
293 bool checkreturn pb_encode_fixed64(pb_ostream_t *stream, const void *value)
295 #ifdef __BIG_ENDIAN__
296 const uint8_t *bytes = value;
298 lebytes[0] = bytes[7];
299 lebytes[1] = bytes[6];
300 lebytes[2] = bytes[5];
301 lebytes[3] = bytes[4];
302 lebytes[4] = bytes[3];
303 lebytes[5] = bytes[2];
304 lebytes[6] = bytes[1];
305 lebytes[7] = bytes[0];
306 return pb_write(stream, lebytes, 8);
308 return pb_write(stream, (const uint8_t*)value, 8);
312 bool checkreturn pb_encode_tag(pb_ostream_t *stream, pb_wire_type_t wiretype, uint32_t field_number)
314 uint64_t tag = wiretype | (field_number << 3);
315 return pb_encode_varint(stream, tag);
318 bool checkreturn pb_encode_tag_for_field(pb_ostream_t *stream, const pb_field_t *field)
320 pb_wire_type_t wiretype;
321 switch (PB_LTYPE(field->type))
323 case PB_LTYPE_VARINT:
324 case PB_LTYPE_SVARINT:
325 wiretype = PB_WT_VARINT;
328 case PB_LTYPE_FIXED32:
329 wiretype = PB_WT_32BIT;
332 case PB_LTYPE_FIXED64:
333 wiretype = PB_WT_64BIT;
337 case PB_LTYPE_STRING:
338 case PB_LTYPE_SUBMESSAGE:
339 wiretype = PB_WT_STRING;
346 return pb_encode_tag(stream, wiretype, field->tag);
349 bool checkreturn pb_encode_string(pb_ostream_t *stream, const uint8_t *buffer, size_t size)
351 if (!pb_encode_varint(stream, (uint64_t)size))
354 return pb_write(stream, buffer, size);
357 bool checkreturn pb_encode_submessage(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
359 /* First calculate the message size using a non-writing substream. */
360 pb_ostream_t substream = {0,0,0,0};
364 if (!pb_encode(&substream, fields, src_struct))
367 size = substream.bytes_written;
369 if (!pb_encode_varint(stream, (uint64_t)size))
372 if (stream->callback == NULL)
373 return pb_write(stream, NULL, size); /* Just sizing */
375 if (stream->bytes_written + size > stream->max_size)
378 /* Use a substream to verify that a callback doesn't write more than
379 * what it did the first time. */
380 substream.callback = stream->callback;
381 substream.state = stream->state;
382 substream.max_size = size;
383 substream.bytes_written = 0;
385 status = pb_encode(&substream, fields, src_struct);
387 stream->bytes_written += substream.bytes_written;
388 stream->state = substream.state;
390 if (substream.bytes_written != size)
398 bool checkreturn pb_enc_varint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
402 switch (field->data_size)
404 case 1: value = *(const uint8_t*)src; break;
405 case 2: value = *(const uint16_t*)src; break;
406 case 4: value = *(const uint32_t*)src; break;
407 case 8: value = *(const uint64_t*)src; break;
408 default: return false;
411 return pb_encode_varint(stream, value);
414 bool checkreturn pb_enc_svarint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
418 switch (field->data_size)
420 case 4: value = *(const int32_t*)src; break;
421 case 8: value = *(const int64_t*)src; break;
422 default: return false;
425 return pb_encode_svarint(stream, value);
428 bool checkreturn pb_enc_fixed64(pb_ostream_t *stream, const pb_field_t *field, const void *src)
431 return pb_encode_fixed64(stream, src);
434 bool checkreturn pb_enc_fixed32(pb_ostream_t *stream, const pb_field_t *field, const void *src)
437 return pb_encode_fixed32(stream, src);
440 bool checkreturn pb_enc_bytes(pb_ostream_t *stream, const pb_field_t *field, const void *src)
442 const pb_bytes_array_t *bytes = (const pb_bytes_array_t*)src;
444 return pb_encode_string(stream, bytes->bytes, bytes->size);
447 bool checkreturn pb_enc_string(pb_ostream_t *stream, const pb_field_t *field, const void *src)
450 return pb_encode_string(stream, (const uint8_t*)src, strlen((const char*)src));
453 bool checkreturn pb_enc_submessage(pb_ostream_t *stream, const pb_field_t *field, const void *src)
455 if (field->ptr == NULL)
458 return pb_encode_submessage(stream, (const pb_field_t*)field->ptr, src);