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)
51 stream.callback = &buf_write;
53 stream.max_size = bufsize;
54 stream.bytes_written = 0;
58 bool checkreturn pb_write(pb_ostream_t *stream, const uint8_t *buf, size_t count)
60 if (stream->callback != NULL)
62 if (stream->bytes_written + count > stream->max_size)
65 if (!stream->callback(stream, buf, count))
69 stream->bytes_written += count;
73 /* Main encoding stuff */
75 /* Callbacks don't need this function because they usually know the data type
76 * without examining the field structure.
77 * Therefore it is static for now.
79 static bool checkreturn encode_array(pb_ostream_t *stream, const pb_field_t *field,
80 const void *pData, size_t count, pb_encoder_t func)
89 if (PB_LTYPE(field->type) <= PB_LTYPE_LAST_PACKABLE)
91 if (!pb_encode_tag(stream, PB_WT_STRING, field->tag))
94 /* Determine the total size of packed array. */
95 if (PB_LTYPE(field->type) == PB_LTYPE_FIXED32)
99 else if (PB_LTYPE(field->type) == PB_LTYPE_FIXED64)
105 pb_ostream_t sizestream = {0,0,0,0};
107 for (i = 0; i < count; i++)
109 if (!func(&sizestream, field, p))
111 p = (const char*)p + field->data_size;
113 size = sizestream.bytes_written;
116 if (!pb_encode_varint(stream, (uint64_t)size))
119 if (stream->callback == NULL)
120 return pb_write(stream, NULL, size); /* Just sizing.. */
124 for (i = 0; i < count; i++)
126 if (!func(stream, field, p))
128 p = (const char*)p + field->data_size;
134 for (i = 0; i < count; i++)
136 if (!pb_encode_tag_for_field(stream, field))
138 if (!func(stream, field, p))
140 p = (const char*)p + field->data_size;
147 bool checkreturn pb_encode(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
149 const pb_field_t *field = fields;
150 const void *pData = src_struct;
152 size_t prev_size = 0;
154 while (field->tag != 0)
156 pb_encoder_t func = PB_ENCODERS[PB_LTYPE(field->type)];
157 pData = (const char*)pData + prev_size + field->data_offset;
158 pSize = (const char*)pData + field->size_offset;
160 prev_size = field->data_size;
161 if (PB_HTYPE(field->type) == PB_HTYPE_ARRAY)
162 prev_size *= field->array_size;
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))
185 if (!encode_array(stream, field, pData, *(const size_t*)pSize, func))
189 case PB_HTYPE_CALLBACK:
191 const pb_callback_t *callback = (const pb_callback_t*)pData;
192 if (callback->funcs.encode != NULL)
194 if (!callback->funcs.encode(stream, field, callback->arg))
207 /* Helper functions */
208 bool checkreturn pb_encode_varint(pb_ostream_t *stream, uint64_t value)
214 return pb_write(stream, (uint8_t*)&value, 1);
218 buffer[i] = (uint8_t)((value & 0x7F) | 0x80);
222 buffer[i-1] &= 0x7F; /* Unset top bit on last byte */
224 return pb_write(stream, buffer, i);
227 bool checkreturn pb_encode_svarint(pb_ostream_t *stream, int64_t value)
231 zigzagged = (uint64_t)(~(value << 1));
233 zigzagged = (uint64_t)(value << 1);
235 return pb_encode_varint(stream, zigzagged);
238 bool checkreturn pb_encode_fixed32(pb_ostream_t *stream, const void *value)
240 #ifdef __BIG_ENDIAN__
241 const uint8_t *bytes = value;
243 lebytes[0] = bytes[3];
244 lebytes[1] = bytes[2];
245 lebytes[2] = bytes[1];
246 lebytes[3] = bytes[0];
247 return pb_write(stream, lebytes, 4);
249 return pb_write(stream, (const uint8_t*)value, 4);
253 bool checkreturn pb_encode_fixed64(pb_ostream_t *stream, const void *value)
255 #ifdef __BIG_ENDIAN__
256 const uint8_t *bytes = value;
258 lebytes[0] = bytes[7];
259 lebytes[1] = bytes[6];
260 lebytes[2] = bytes[5];
261 lebytes[3] = bytes[4];
262 lebytes[4] = bytes[3];
263 lebytes[5] = bytes[2];
264 lebytes[6] = bytes[1];
265 lebytes[7] = bytes[0];
266 return pb_write(stream, lebytes, 8);
268 return pb_write(stream, (const uint8_t*)value, 8);
272 bool checkreturn pb_encode_tag(pb_ostream_t *stream, pb_wire_type_t wiretype, uint32_t field_number)
274 uint64_t tag = wiretype | (field_number << 3);
275 return pb_encode_varint(stream, tag);
278 bool checkreturn pb_encode_tag_for_field(pb_ostream_t *stream, const pb_field_t *field)
280 pb_wire_type_t wiretype;
281 switch (PB_LTYPE(field->type))
283 case PB_LTYPE_VARINT:
284 case PB_LTYPE_SVARINT:
285 wiretype = PB_WT_VARINT;
288 case PB_LTYPE_FIXED32:
289 wiretype = PB_WT_32BIT;
292 case PB_LTYPE_FIXED64:
293 wiretype = PB_WT_64BIT;
297 case PB_LTYPE_STRING:
298 case PB_LTYPE_SUBMESSAGE:
299 wiretype = PB_WT_STRING;
306 return pb_encode_tag(stream, wiretype, field->tag);
309 bool checkreturn pb_encode_string(pb_ostream_t *stream, const uint8_t *buffer, size_t size)
311 if (!pb_encode_varint(stream, (uint64_t)size))
314 return pb_write(stream, buffer, size);
317 bool checkreturn pb_encode_submessage(pb_ostream_t *stream, const pb_field_t fields[], const void *src_struct)
319 /* First calculate the message size using a non-writing substream. */
320 pb_ostream_t substream = {0,0,0,0};
324 if (!pb_encode(&substream, fields, src_struct))
327 size = substream.bytes_written;
329 if (!pb_encode_varint(stream, (uint64_t)size))
332 if (stream->callback == NULL)
333 return pb_write(stream, NULL, size); /* Just sizing */
335 if (stream->bytes_written + size > stream->max_size)
338 /* Use a substream to verify that a callback doesn't write more than
339 * what it did the first time. */
340 substream.callback = stream->callback;
341 substream.state = stream->state;
342 substream.max_size = size;
343 substream.bytes_written = 0;
345 status = pb_encode(&substream, fields, src_struct);
347 stream->bytes_written += substream.bytes_written;
348 stream->state = substream.state;
350 if (substream.bytes_written != size)
358 bool checkreturn pb_enc_varint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
362 switch (field->data_size)
364 case 1: value = *(const uint8_t*)src; break;
365 case 2: value = *(const uint16_t*)src; break;
366 case 4: value = *(const uint32_t*)src; break;
367 case 8: value = *(const uint64_t*)src; break;
368 default: return false;
371 return pb_encode_varint(stream, value);
374 bool checkreturn pb_enc_svarint(pb_ostream_t *stream, const pb_field_t *field, const void *src)
378 switch (field->data_size)
380 case 4: value = *(const int32_t*)src; break;
381 case 8: value = *(const int64_t*)src; break;
382 default: return false;
385 return pb_encode_svarint(stream, value);
388 bool checkreturn pb_enc_fixed64(pb_ostream_t *stream, const pb_field_t *field, const void *src)
391 return pb_encode_fixed64(stream, src);
394 bool checkreturn pb_enc_fixed32(pb_ostream_t *stream, const pb_field_t *field, const void *src)
397 return pb_encode_fixed32(stream, src);
400 bool checkreturn pb_enc_bytes(pb_ostream_t *stream, const pb_field_t *field, const void *src)
402 const pb_bytes_array_t *bytes = (const pb_bytes_array_t*)src;
404 return pb_encode_string(stream, bytes->bytes, bytes->size);
407 bool checkreturn pb_enc_string(pb_ostream_t *stream, const pb_field_t *field, const void *src)
410 return pb_encode_string(stream, (const uint8_t*)src, strlen((const char*)src));
413 bool checkreturn pb_enc_submessage(pb_ostream_t *stream, const pb_field_t *field, const void *src)
415 if (field->ptr == NULL)
418 return pb_encode_submessage(stream, (const pb_field_t*)field->ptr, src);