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/ IRIX Base Documentation 2002 November / SGI IRIX Base Documentation 2002 November.iso / usr / share / catman / p_man / catD / drv_usecwait.z / drv_usecwait
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Text File  |  2002-10-03  |  4.9 KB  |  132 lines
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  4. ddddrrrrvvvv____uuuusssseeeeccccwwwwaaaaiiiitttt((((DDDD3333))))                                              ddddrrrrvvvv____uuuusssseeeeccccwwwwaaaaiiiitttt((((DDDD3333))))
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  8. NNNNAAAAMMMMEEEE
  9.      _dddd_rrrr_vvvv______uuuu_ssss_eeee_cccc_wwww_aaaa_iiii_tttt - busy-wait for specified interval
  10.  
  11. SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS
  12.      _####_iiii_nnnn_cccc_llll_uuuu_dddd_eeee _<<<<_ssss_yyyy_ssss_////_tttt_yyyy_pppp_eeee_ssss_...._hhhh_>>>>
  13.      _####_iiii_nnnn_cccc_llll_uuuu_dddd_eeee _<<<<_ssss_yyyy_ssss_////_dddd_dddd_iiii_...._hhhh_>>>>
  14.      _vvvv_oooo_iiii_dddd _dddd_rrrr_vvvv______uuuu_ssss_eeee_cccc_wwww_aaaa_iiii_tttt_((((_cccc_llll_oooo_cccc_kkkk______tttt _m_i_c_r_o_s_e_c_s_))))_;;;;
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  16.    AAAArrrrgggguuuummmmeeeennnnttttssss
  17.      _m_i_c_r_o_s_e_c_s The number of microseconds to busy-wait.
  18.  
  19. DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
  20.      _dddd_rrrr_vvvv______uuuu_ssss_eeee_cccc_wwww_aaaa_iiii_tttt causes the caller to busy-wait for at least the number of
  21.      microseconds specified by _m_i_c_r_o_s_e_c_s.  The amount of time spent busy-
  22.      waiting may be greater than the time specified by _m_i_c_r_o_s_e_c_s but will not
  23.      be less.
  24.  
  25.    RRRReeeettttuuuurrrrnnnn VVVVaaaalllluuuueeeessss
  26.      None
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  28. UUUUSSSSAAAAGGGGEEEE
  29.      _dddd_rrrr_vvvv______uuuu_ssss_eeee_cccc_wwww_aaaa_iiii_tttt should only be used to wait for short periods of time (less
  30.      than a clock tick) or when it is necessary to wait without sleeping (for
  31.      example, at interrupt level).  When the desired delay is at least as long
  32.      as clock tick and it is possible to sleep, the _dddd_eeee_llll_aaaa_yyyy(D3) function should
  33.      be used instead since it will not waste processor time busy-waiting as
  34.      _dddd_rrrr_vvvv______uuuu_ssss_eeee_cccc_wwww_aaaa_iiii_tttt does.
  35.  
  36.      Because excessive busy-waiting is wasteful the driver should only make
  37.      calls to _dddd_rrrr_vvvv______uuuu_ssss_eeee_cccc_wwww_aaaa_iiii_tttt as needed, and only for as much time as needed.
  38.      _dddd_rrrr_vvvv______uuuu_ssss_eeee_cccc_wwww_aaaa_iiii_tttt does not raise the interrupt priority level; if the driver
  39.      wishes to block interrupts for the duration of the wait, it is the
  40.      driver's responsibility to set the priority level before the call and
  41.      restore it to its original value afterward.
  42.  
  43.    LLLLeeeevvvveeeellll
  44.      Initialization, Base or Interrupt.
  45.  
  46.    SSSSyyyynnnncccchhhhrrrroooonnnniiiizzzzaaaattttiiiioooonnnn CCCCoooonnnnssssttttrrrraaaaiiiinnnnttttssss
  47.      Does not sleep.
  48.  
  49.      Driver-defined basic locks, read/write locks, and sleep locks may be held
  50.      across calls to this function.
  51.  
  52.    WWWWaaaarrrrnnnniiiinnnnggggssss
  53.      Busy-waiting can increase the preemption latency experienced by high
  54.      priority processes.  Since short and bounded preemption latency can be
  55.      critical in a real time environment, drivers intended for use in such an
  56.      environment should not use this interface or should limit the length of
  57.      the wait to an appropriately short length of time.
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  62.                                                                         PPPPaaaaggggeeee 1111
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  69. ddddrrrrvvvv____uuuusssseeeeccccwwwwaaaaiiiitttt((((DDDD3333))))                                              ddddrrrrvvvv____uuuusssseeeeccccwwwwaaaaiiiitttt((((DDDD3333))))
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  73. RRRREEEEFFFFEEEERRRREEEENNNNCCCCEEEESSSS
  74.      _dddd_eeee_llll_aaaa_yyyy(D3), _dddd_rrrr_vvvv______hhhh_zzzz_tttt_oooo_uuuu_ssss_eeee_cccc(D3), _dddd_rrrr_vvvv______uuuu_ssss_eeee_cccc_tttt_oooo_hhhh_zzzz(D3), _iiii_tttt_iiii_mmmm_eeee_oooo_uuuu_tttt(D3),
  75.      _uuuu_nnnn_tttt_iiii_mmmm_eeee_oooo_uuuu_tttt(D3)
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  128.                                                                         PPPPaaaaggggeeee 2222
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