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 pb_encode(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
158 const pb_field_t *field = fields;
159 const void *pData = src_struct;
161 size_t prev_size = 0;
163 while (field->tag != 0)
165 pb_encoder_t func = PB_ENCODERS[PB_LTYPE(field->type)];
166 pData = (const char*)pData + prev_size + field->data_offset;
167 pSize = (const char*)pData + field->size_offset;
169 prev_size = field->data_size;
170 if (PB_HTYPE(field->type) == PB_HTYPE_REPEATED)
171 prev_size *= field->array_size;
173 switch (PB_HTYPE(field->type))
175 case PB_HTYPE_REQUIRED:
176 if (!pb_encode_tag_for_field(stream, field))
178 if (!func(stream, field, pData))
182 case PB_HTYPE_OPTIONAL:
183 if (*(const bool*)pSize)
185 if (!pb_encode_tag_for_field(stream, field))
188 if (!func(stream, field, pData))
193 case PB_HTYPE_REPEATED:
194 if (!encode_array(stream, field, pData, *(const size_t*)pSize, func))
198 case PB_HTYPE_CALLBACK:
200 const pb_callback_t *callback = (const pb_callback_t*)pData;
201 if (callback->funcs.encode != NULL)
203 if (!callback->funcs.encode(stream, field, callback->arg))
216 /* Helper functions */
217 bool checkreturn pb_encode_varint(pb_ostream_t *stream, uint64_t value)
223 return pb_write(stream, (uint8_t*)&value, 1);
227 buffer[i] = (uint8_t)((value & 0x7F) | 0x80);
231 buffer[i-1] &= 0x7F; /* Unset top bit on last byte */
233 return pb_write(stream, buffer, i);
236 bool checkreturn pb_encode_svarint(pb_ostream_t *stream, int64_t value)
240 zigzagged = (uint64_t)(~(value << 1));
242 zigzagged = (uint64_t)(value << 1);
244 return pb_encode_varint(stream, zigzagged);
247 bool checkreturn pb_encode_fixed32(pb_ostream_t *stream, const void *value)
249 #ifdef __BIG_ENDIAN__
250 const uint8_t *bytes = value;
252 lebytes[0] = bytes[3];
253 lebytes[1] = bytes[2];
254 lebytes[2] = bytes[1];
255 lebytes[3] = bytes[0];
256 return pb_write(stream, lebytes, 4);
258 return pb_write(stream, (const uint8_t*)value, 4);
262 bool checkreturn pb_encode_fixed64(pb_ostream_t *stream, const void *value)
264 #ifdef __BIG_ENDIAN__
265 const uint8_t *bytes = value;
267 lebytes[0] = bytes[7];
268 lebytes[1] = bytes[6];
269 lebytes[2] = bytes[5];
270 lebytes[3] = bytes[4];
271 lebytes[4] = bytes[3];
272 lebytes[5] = bytes[2];
273 lebytes[6] = bytes[1];
274 lebytes[7] = bytes[0];
275 return pb_write(stream, lebytes, 8);
277 return pb_write(stream, (const uint8_t*)value, 8);
281 bool checkreturn pb_encode_tag(pb_ostream_t *stream, pb_wire_type_t wiretype, uint32_t field_number)
283 uint64_t tag = wiretype | (field_number << 3);
284 return pb_encode_varint(stream, tag);
287 bool checkreturn pb_encode_tag_for_field(pb_ostream_t *stream, const pb_field_t *field)
289 pb_wire_type_t wiretype;
290 switch (PB_LTYPE(field->type))
292 case PB_LTYPE_VARINT:
293 case PB_LTYPE_SVARINT:
294 wiretype = PB_WT_VARINT;
297 case PB_LTYPE_FIXED32:
298 wiretype = PB_WT_32BIT;
301 case PB_LTYPE_FIXED64:
302 wiretype = PB_WT_64BIT;
306 case PB_LTYPE_STRING:
307 case PB_LTYPE_SUBMESSAGE:
308 wiretype = PB_WT_STRING;
315 return pb_encode_tag(stream, wiretype, field->tag);
318 bool checkreturn pb_encode_string(pb_ostream_t *stream, const uint8_t *buffer, size_t size)
320 if (!pb_encode_varint(stream, (uint64_t)size))
323 return pb_write(stream, buffer, size);
326 bool checkreturn pb_encode_submessage(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
328 /* First calculate the message size using a non-writing substream. */
329 pb_ostream_t substream = {0,0,0,0};
333 if (!pb_encode(&substream, fields, src_struct))
336 size = substream.bytes_written;
338 if (!pb_encode_varint(stream, (uint64_t)size))
341 if (stream->callback == NULL)
342 return pb_write(stream, NULL, size); /* Just sizing */
344 if (stream->bytes_written + size > stream->max_size)
347 /* Use a substream to verify that a callback doesn't write more than
348 * what it did the first time. */
349 substream.callback = stream->callback;
350 substream.state = stream->state;
351 substream.max_size = size;
352 substream.bytes_written = 0;
354 status = pb_encode(&substream, fields, src_struct);
356 stream->bytes_written += substream.bytes_written;
357 stream->state = substream.state;
359 if (substream.bytes_written != size)
367 bool checkreturn pb_enc_varint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
371 switch (field->data_size)
373 case 1: value = *(const uint8_t*)src; break;
374 case 2: value = *(const uint16_t*)src; break;
375 case 4: value = *(const uint32_t*)src; break;
376 case 8: value = *(const uint64_t*)src; break;
377 default: return false;
380 return pb_encode_varint(stream, value);
383 bool checkreturn pb_enc_svarint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
387 switch (field->data_size)
389 case 4: value = *(const int32_t*)src; break;
390 case 8: value = *(const int64_t*)src; break;
391 default: return false;
394 return pb_encode_svarint(stream, value);
397 bool checkreturn pb_enc_fixed64(pb_ostream_t *stream, const pb_field_t *field, const void *src)
400 return pb_encode_fixed64(stream, src);
403 bool checkreturn pb_enc_fixed32(pb_ostream_t *stream, const pb_field_t *field, const void *src)
406 return pb_encode_fixed32(stream, src);
409 bool checkreturn pb_enc_bytes(pb_ostream_t *stream, const pb_field_t *field, const void *src)
411 const pb_bytes_array_t *bytes = (const pb_bytes_array_t*)src;
413 return pb_encode_string(stream, bytes->bytes, bytes->size);
416 bool checkreturn pb_enc_string(pb_ostream_t *stream, const pb_field_t *field, const void *src)
419 return pb_encode_string(stream, (const uint8_t*)src, strlen((const char*)src));
422 bool checkreturn pb_enc_submessage(pb_ostream_t *stream, const pb_field_t *field, const void *src)
424 if (field->ptr == NULL)
427 return pb_encode_submessage(stream, (const pb_field_t*)field->ptr, src);