aplfw/library/container/packetbuf/packetbuf_getbuf.c

   1 /**
   2  *  Hyper Operating System  Application Framework
   3  *
   4  * @file  packetbuf.h
   5  * @brief %jp{パケットデータ用バッファクラス}
   6  *
   7  * Copyright (C) 2002-2007 by Project HOS
   8  * http://sourceforge.jp/projects/hos/
   9  */
  10
  11
  12 #include "packetbuf_local.h"
  13
  14
  15
  16 /** 送信用バッファの取得(省コピー) */
  17 unsigned int PacketBuf_GetBuf(C_PACKETBUF *self, void **ppBuf, unsigned int uiSize)
  18 {
  19         unsigned int uiAllocSize;
  20
  21         /* 割り当てサイズ計算 */
  22         uiAllocSize = PACKETBUF_DATASIZE(uiSize) + sizeof(unsigned int);
  23
  24         /* 割り当て可能性チェック */
  25         if ( self->uiTail >= self->uiHead )
  26         {
  27                 if ( self->uiTail > self->uiBufSize - uiAllocSize )
  28                 {
  29                         /* 折り返し可能かチェック */
  30                         if ( self->uiHead <= uiAllocSize )
  31                         {
  32                                 return 0;       /* 割り当て不可 */
  33                         }
  34
  35                         /* 折り返し */
  36                         self->uiReturnPoint = self->uiTail;
  37                         self->uiTail        = 0;
  38                 }
  39         }
  40         else
  41         {
  42                 if ( self->uiHead - self->uiTail <= uiAllocSize )
  43                 {
  44                         return 0;       /* 割り当て不可 */
  45                 }
  46         }
  47
  48         /* 割り当てたバッファを返す */
  49         *ppBuf = (void *)(self->pubBuf + self->uiTail + sizeof(unsigned int));
  50
  51         return uiSize;  /* 割り当てたサイズを返す */
  52 }
  53
  54
  55 /* end of file */