libust/header-inline.h

   1 /*
   2  * Copyright (C) 2008 - Mathieu Desnoyers (mathieu.desnoyers@polymtl.ca)
   3  *
   4  * This library is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Lesser General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2.1 of the License, or (at your option) any later version.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public
  15  * License along with this library; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
  17  */
  18
  19 #ifndef UST_HEADER_INLINE_H
  20 #define UST_HEADER_INLINE_H
  21
  22 #include <ust/core.h>
  23
  24 /*
  25  * ust_get_header_size
  26  *
  27  * Calculate alignment offset to 32-bits. This is the alignment offset of the
  28  * event header.
  29  *
  30  * Important note :
  31  * The event header must be 32-bits. The total offset calculated here :
  32  *
  33  * Alignment of header struct on 32 bits (min arch size, header size)
  34  * + sizeof(header struct)  (32-bits)
  35  * + (opt) u16 (ext. event id)
  36  * + (opt) u16 (event_size) (if event_size == 0xFFFFUL, has ext. event size)
  37  * + (opt) u32 (ext. event size)
  38  * + (opt) u64 full TSC (aligned on min(64-bits, arch size))
  39  *
  40  * The payload must itself determine its own alignment from the biggest type it
  41  * contains.
  42  * */
  43 static __inline__ unsigned char ust_get_header_size(
  44                 struct ust_channel *channel,
  45                 size_t offset,
  46                 size_t data_size,
  47                 size_t *before_hdr_pad,
  48                 unsigned int rflags)
  49 {
  50         size_t orig_offset = offset;
  51         size_t padding;
  52
  53         padding = ltt_align(offset, sizeof(struct ltt_event_header));
  54         offset += padding;
  55         offset += sizeof(struct ltt_event_header);
  56
  57         if(unlikely(rflags)) {
  58                 switch (rflags) {
  59                 case LTT_RFLAG_ID_SIZE_TSC:
  60                         offset += sizeof(u16) + sizeof(u16);
  61                         if (data_size >= 0xFFFFU)
  62                                 offset += sizeof(u32);
  63                         offset += ltt_align(offset, sizeof(u64));
  64                         offset += sizeof(u64);
  65                         break;
  66                 case LTT_RFLAG_ID_SIZE:
  67                         offset += sizeof(u16) + sizeof(u16);
  68                         if (data_size >= 0xFFFFU)
  69                                 offset += sizeof(u32);
  70                         break;
  71                 case LTT_RFLAG_ID:
  72                         offset += sizeof(u16);
  73                         break;
  74                 }
  75         }
  76
  77         *before_hdr_pad = padding;
  78         return offset - orig_offset;
  79 }
  80
  81 #endif /* UST_HEADER_INLINE_H */