pb_common.c

00001 /* pb_common.c: Common support functions for pb_encode.c and pb_decode.c.
00002  *
00003  * 2014 Petteri Aimonen <jpa@kapsi.fi>
00004  */
00005 
00006 #include "pb_common.h"
00007 
00008 bool pb_field_iter_begin(pb_field_iter_t *iter, const pb_field_t *fields, void *dest_struct)
00009 {
00010     iter->start = fields;
00011     iter->pos = fields;
00012     iter->required_field_index = 0;
00013     iter->dest_struct = dest_struct;
00014     iter->pData = (char*)dest_struct + iter->pos->data_offset;
00015     iter->pSize = (char*)iter->pData + iter->pos->size_offset;
00016     
00017     return (iter->pos->tag != 0);
00018 }
00019 
00020 bool pb_field_iter_next(pb_field_iter_t *iter)
00021 {
00022     const pb_field_t *prev_field = iter->pos;
00023 
00024     if (prev_field->tag == 0)
00025     {
00026         /* Handle empty message types, where the first field is already the terminator.
00027          * In other cases, the iter->pos never points to the terminator. */
00028         return false;
00029     }
00030     
00031     iter->pos++;
00032     
00033     if (iter->pos->tag == 0)
00034     {
00035         /* Wrapped back to beginning, reinitialize */
00036         (void)pb_field_iter_begin(iter, iter->start, iter->dest_struct);
00037         return false;
00038     }
00039     else
00040     {
00041         /* Increment the pointers based on previous field size */
00042         size_t prev_size = prev_field->data_size;
00043     
00044         if (PB_HTYPE(prev_field->type) == PB_HTYPE_ONEOF &&
00045             PB_HTYPE(iter->pos->type) == PB_HTYPE_ONEOF)
00046         {
00047             /* Don't advance pointers inside unions */
00048             prev_size = 0;
00049             iter->pData = (char*)iter->pData - prev_field->data_offset;
00050         }
00051         else if (PB_ATYPE(prev_field->type) == PB_ATYPE_STATIC &&
00052                  PB_HTYPE(prev_field->type) == PB_HTYPE_REPEATED)
00053         {
00054             /* In static arrays, the data_size tells the size of a single entry and
00055              * array_size is the number of entries */
00056             prev_size *= prev_field->array_size;
00057         }
00058         else if (PB_ATYPE(prev_field->type) == PB_ATYPE_POINTER)
00059         {
00060             /* Pointer fields always have a constant size in the main structure.
00061              * The data_size only applies to the dynamically allocated area. */
00062             prev_size = sizeof(void*);
00063         }
00064 
00065         if (PB_HTYPE(prev_field->type) == PB_HTYPE_REQUIRED)
00066         {
00067             /* Count the required fields, in order to check their presence in the
00068              * decoder. */
00069             iter->required_field_index++;
00070         }
00071     
00072         iter->pData = (char*)iter->pData + prev_size + iter->pos->data_offset;
00073         iter->pSize = (char*)iter->pData + iter->pos->size_offset;
00074         return true;
00075     }
00076 }
00077 
00078 bool pb_field_iter_find(pb_field_iter_t *iter, uint32_t tag)
00079 {
00080     const pb_field_t *start = iter->pos;
00081     
00082     do {
00083         if (iter->pos->tag == tag &&
00084             PB_LTYPE(iter->pos->type) != PB_LTYPE_EXTENSION)
00085         {
00086             /* Found the wanted field */
00087             return true;
00088         }
00089         
00090         (void)pb_field_iter_next(iter);
00091     } while (iter->pos != start);
00092     
00093     /* Searched all the way back to start, and found nothing. */
00094     return false;
00095 }
00096