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Freescale 9S12 系列单片机应用笔记（SCI）2

时间：11-20 来源：互联网 点击：

  2. aseSCI0:
  3. pbuf=&SCI0Buf;
  4. break;

    caseSCI1:

  5. pbuf=&SCI1Buf;
  6. break;

    default:

  7. *err=SCI_BAD_CH;
  8. return(0);
  9. }
  10. OS_ENTER_CRITICAL();
  11. if(pbuf->RingBufRxCtr>0)/*Seeifbufferisempty*/
  12. {
  13. pbuf->RingBufRxCtr--;/*No,decrementcharactercount*/
  14. c=*pbuf->RingBufRxOutPtr++;/*Getcharacterfrombuffer*/
  15. if(pbuf->RingBufRxOutPtr==&pbuf->RingBufRx[SCI_RX_BUF_SIZE])
  16. {
  17. pbuf->RingBufRxOutPtr=&pbuf->RingBufRx[0];/*WrapOUTpointer*/
  18. }
  19. OS_EXIT_CRITICAL();
  20. *err=SCI_NO_ERR;
  21. return(c);
  22. }
  23. else
  24. {
  25. OS_EXIT_CRITICAL();
  26. *err=SCI_RX_EMPTY;
  27. c=0;/*Bufferisempty,return0*/
  28. return(c);
  29. }
  30. }

  31. /**
  32. *Tosendacharacteronthecommunicationschannel.
  33. *ThecharactertosendisfirstinsertedintotheTxbufferandwillbesentby
  34. *theTxISR.Ifthisisthefirstcharacterplacedintothebuffer,theTxISRwillbe
  35. *enabled.IftheTxbufferisfull,thecharacterwillnotbesent(i.e.itwillbelost)
  36. *
  37. *@paramport,portcanbeSCI0/SCI1
  38. *@returnCOMM_NO_ERRifthefunctionwassuccessful(thebufferwasnotfull)
  39. *COMM_TX_FULLifthebufferwasfull
  40. *COMM_BAD_CHifyouhavespecifiedanincorrectchannel
  41. */
  42. unsignedcharSCIPutCharB(unsignedcharport,unsignedcharc)
  43. {
  44. unsignedcharcpu_sr;
  46. SCI_RING_BUF*pbuf;
  48. /*Obtainpointertocommunicationschannel*/
  49. switch(port)
  50. {
  51. caseSCI0:
  52. pbuf=&SCI0Buf;
  53. break;

    caseSCI1:

  54. pbuf=&SCI1Buf;
  55. break;

    default:

  56. return(SCI_BAD_CH);
  57. }

    OS_ENTER_CRITICAL();

  58. if(pbuf->RingBufTxCtr
  59. {
  60. pbuf->RingBufTxCtr++;/*No,incrementcharactercount*/
  61. *pbuf->RingBufTxInPtr++=c;/*Putcharacterintobuffer*/
  62. if(pbuf->RingBufTxInPtr==&pbuf->RingBufTx[SCI_TX_BUF_SIZE])
  63. {
  64. pbuf->RingBufTxInPtr=&pbuf->RingBufTx[0];/*WrapINpointer*/
  65. }
  66. if(pbuf->RingBufTxCtr==1)
  67. {/*Seeifthisisthefirstcharacter*/
  68. SCIEnableTxInt(port);/*Yes,EnableTxinterrupts*/
  69. OS_EXIT_CRITICAL();
  70. }
  71. else
  72. {
  73. OS_EXIT_CRITICAL();
  74. }
  75. return(SCI_NO_ERR);
  76. }
  77. else
  78. {
  79. OS_EXIT_CRITICAL();
  80. return(SCI_TX_FULL);
  81. }
  82. }

    /**

  83. *Toinitializethecommunicationsmodule.
  84. *Youmustcallthisfunctionbeforecallinganyotherfunctions.
  85. */
  86. voidSCIBufferInit(void)
  87. {
  88. SCI_RING_BUF*pbuf;
  90. /*InitializetheringbufferforSCI0*/
  91. pbuf=&SCI0Buf;
  92. pbuf->RingBufRxCtr=0;
  93. pbuf->RingBufRxInPtr=&pbuf->RingBufRx[0];
  94. pbuf->RingBufRxOutPtr=&pbuf->RingBufRx[0];
  95. pbuf->RingBufTxCtr=0;
  96. pbuf->RingBufTxInPtr=&pbuf->RingBufTx[0];
  97. pbuf->RingBufTxOutPtr=&pbuf->RingBufTx[0];
  99. /*InitializetheringbufferforSCI1*/
  100. pbuf=&SCI1Buf;
  101. pbuf->RingBufRxCtr=0;
  102. pbuf->RingBufRxInPtr=&pbuf->RingBufRx[0];
  103. pbuf->RingBufRxOutPtr=&pbuf->RingBufRx[0];
  104. pbuf->RingBufTxCtr=0;
  105. pbuf->RingBufTxInPtr=&pbuf->RingBufTx[0];
  106. pbuf->RingBufTxOutPtr=&pbuf->RingBufTx[0];
  107. }

  108. /**
  109. *Toseeifanycharacterisavailablefromthecommunicationschannel.
  110. *
  111. *@paramport,portcanbeSCI0/SCI1
  112. *@returnIfatleastonecharacterisavailable,thefunctionreturns
  113. *FALSE(0)otherwise,thefunctionreturnsTRUE(1).
  114. */
  115. unsignedcharSCIBufferIsEmpty(unsignedcharport)
  116. {
  117. unsignedcharcpu_sr;
  118. unsignedcharempty;
  119. SCI_RING_BUF*pbuf;
  121. /*Obtainpointertocommunicationschannel*/
  122. switch(port)
  123. {
  124. caseSCI0:
  125. pbuf=&SCI0Buf;
  126. break;

    caseSCI1:

  127. pbuf=&SCI1Buf;
  128. break;

    default:

  129. return(1);
  130. }
  131. OS_ENTER_CRITICAL();
  132. if(pbuf->RingBufRxCtr>0)/*Seeifbufferisempty*/
  133. {
  134. empty=0;/*BufferisNOTempty*/
  135. }
  136. else
  137. {
  138. empty=1;/*Bufferisempty*/
  139. }
  140. OS_EXIT_CRITICAL();
  141. return(empty);
  142. }

  143. /**
  144. *ToseeifanymorecharacterscanbeplacedintheTxbuffer.
  145. *Inotherwords,thisfunctionchecktoseeiftheTxbufferisfull.
  146. *
  147. *@paramport,portcanbeSCI0/SCI1
  148. *@returnIfthebufferisfull,thefunctionreturnsTRUE
  149. *otherwise,thefunctionreturnsFALSE.
  150. */
  151. unsignedcharSCIBufferIsFull(unsignedcharport)
  152. {
  153. unsignedcharcpu_sr;
  155. charfull;
  156. SCI_RING_BUF*pbuf;
  158. /*Obtainpointertocommunicationschannel*/
  159. switch(port)
  160. {
  161. caseSCI0:
  162. pbuf=&SCI0Buf;
  163. break;

    caseSCI1:

  164. pbuf=&SCI1Buf;
  165. break;

    default:

  166. return(1);
  167. }
  168. OS_ENTER_CRITICAL();
  169. if(pbuf->RingBufTxCtr
  170. {/*Seeifbufferisfull*/
  171. full=0;/*BufferisNOTfull*/
  172. }
  173. else
  174. {
  175. full=1;/*Bufferisfull*/
  176. }
  177. OS_EXIT_CRITICAL();
  178. return(full);
  179. }

  180. //ThisfunctioniscalledbytheRxISRtoinsertacharacterintothereceiveringbuffer.
  181. staticvoidSCIPutRxChar(u

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