pb_common.c

   1 /* pb_common.c: Common support functions for pb_encode.c and pb_decode.c.
   2  *
   3  * 2014 Petteri Aimonen <jpa@kapsi.fi>
   4  */
   5
   6 #include "pb_common.h"
   7
   8 void pb_field_iter_begin(pb_field_iter_t *iter, const pb_field_t *fields, void *dest_struct)
   9 {
  10     iter->start = fields;
  11     iter->pos = fields;
  12     iter->required_field_index = 0;
  13     iter->dest_struct = dest_struct;
  14     iter->pData = (char*)dest_struct + iter->pos->data_offset;
  15     iter->pSize = (char*)iter->pData + iter->pos->size_offset;
  16 }
  17
  18 bool pb_field_iter_next(pb_field_iter_t *iter)
  19 {
  20     const pb_field_t *prev_field = iter->pos;
  21
  22     if (prev_field->tag == 0)
  23     {
  24         /* Handle empty message types, where the first field is already the terminator.
  25          * In other cases, the iter->pos never points to the terminator. */
  26         return false;
  27     }
  28
  29     iter->pos++;
  30
  31     if (iter->pos->tag == 0)
  32     {
  33         /* Wrapped back to beginning, reinitialize */
  34         pb_field_iter_begin(iter, iter->start, iter->dest_struct);
  35         return false;
  36     }
  37     else
  38     {
  39         /* Increment the pointers based on previous field size */
  40         size_t prev_size = prev_field->data_size;
  41
  42         if (PB_ATYPE(prev_field->type) == PB_ATYPE_STATIC &&
  43             PB_HTYPE(prev_field->type) == PB_HTYPE_REPEATED)
  44         {
  45             /* In static arrays, the data_size tells the size of a single entry and
  46              * array_size is the number of entries */
  47             prev_size *= prev_field->array_size;
  48         }
  49         else if (PB_ATYPE(prev_field->type) == PB_ATYPE_POINTER)
  50         {
  51             /* Pointer fields always have a constant size in the main structure.
  52              * The data_size only applies to the dynamically allocated area. */
  53             prev_size = sizeof(void*);
  54         }
  55
  56         if (PB_HTYPE(prev_field->type) == PB_HTYPE_REQUIRED)
  57         {
  58             /* Count the required fields, in order to check their presence in the
  59              * decoder. */
  60             iter->required_field_index++;
  61         }
  62
  63         iter->pData = (char*)iter->pData + prev_size + iter->pos->data_offset;
  64         iter->pSize = (char*)iter->pData + iter->pos->size_offset;
  65         return true;
  66     }
  67 }
  68
  69 bool pb_field_iter_find(pb_field_iter_t *iter, uint32_t tag)
  70 {
  71     const pb_field_t *start = iter->pos;
  72
  73     do {
  74         if (iter->pos->tag == tag &&
  75             PB_LTYPE(iter->pos->type) != PB_LTYPE_EXTENSION)
  76         {
  77             /* Found the wanted field */
  78             return true;
  79         }
  80
  81         (void)pb_field_iter_next(iter);
  82     } while (iter->pos != start);
  83
  84     /* Searched all the way back to start, and found nothing. */
  85     return false;
  86 }
  87
  88