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 bool 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     return (iter->pos->tag != 0);
  18 }
  19
  20 bool pb_field_iter_next(pb_field_iter_t *iter)
  21 {
  22     const pb_field_t *prev_field = iter->pos;
  23
  24     if (prev_field->tag == 0)
  25     {
  26         /* Handle empty message types, where the first field is already the terminator.
  27          * In other cases, the iter->pos never points to the terminator. */
  28         return false;
  29     }
  30
  31     iter->pos++;
  32
  33     if (iter->pos->tag == 0)
  34     {
  35         /* Wrapped back to beginning, reinitialize */
  36         (void)pb_field_iter_begin(iter, iter->start, iter->dest_struct);
  37         return false;
  38     }
  39     else
  40     {
  41         /* Increment the pointers based on previous field size */
  42         size_t prev_size = prev_field->data_size;
  43
  44         if (PB_ATYPE(prev_field->type) == PB_ATYPE_STATIC &&
  45             PB_HTYPE(prev_field->type) == PB_HTYPE_REPEATED)
  46         {
  47             /* In static arrays, the data_size tells the size of a single entry and
  48              * array_size is the number of entries */
  49             prev_size *= prev_field->array_size;
  50         }
  51         else if (PB_ATYPE(prev_field->type) == PB_ATYPE_POINTER)
  52         {
  53             /* Pointer fields always have a constant size in the main structure.
  54              * The data_size only applies to the dynamically allocated area. */
  55             prev_size = sizeof(void*);
  56         }
  57
  58         if (PB_HTYPE(prev_field->type) == PB_HTYPE_REQUIRED)
  59         {
  60             /* Count the required fields, in order to check their presence in the
  61              * decoder. */
  62             iter->required_field_index++;
  63         }
  64
  65         iter->pData = (char*)iter->pData + prev_size + iter->pos->data_offset;
  66         iter->pSize = (char*)iter->pData + iter->pos->size_offset;
  67         return true;
  68     }
  69 }
  70
  71 bool pb_field_iter_find(pb_field_iter_t *iter, uint32_t tag)
  72 {
  73     const pb_field_t *start = iter->pos;
  74
  75     do {
  76         if (iter->pos->tag == tag &&
  77             PB_LTYPE(iter->pos->type) != PB_LTYPE_EXTENSION)
  78         {
  79             /* Found the wanted field */
  80             return true;
  81         }
  82
  83         (void)pb_field_iter_next(iter);
  84     } while (iter->pos != start);
  85
  86     /* Searched all the way back to start, and found nothing. */
  87     return false;
  88 }
  89
  90