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/ IRIX Base Documentation 2002 November / SGI IRIX Base Documentation 2002 November.iso / usr / share / catman / p_man / cat3c / sem_getvalue.z / sem_getvalue
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Text File  |  2002-10-03  |  2.8 KB  |  66 lines
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  4. sssseeeemmmm____ggggeeeettttvvvvaaaalllluuuueeee((((3333CCCC))))                                              sssseeeemmmm____ggggeeeettttvvvvaaaalllluuuueeee((((3333CCCC))))
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  8. NNNNAAAAMMMMEEEE
  9.      _ssss_eeee_mmmm______gggg_eeee_tttt_vvvv_aaaa_llll_uuuu_eeee - get the value of a posix named or unnamed semaphore
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  11. SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS
  12.      _####_iiii_nnnn_cccc_llll_uuuu_dddd_eeee _<<<<_ssss_eeee_mmmm_aaaa_pppp_hhhh_oooo_rrrr_eeee_...._hhhh_>>>>
  13.      _iiii_nnnn_tttt _ssss_eeee_mmmm______gggg_eeee_tttt_vvvv_aaaa_llll_uuuu_eeee_((((_ssss_eeee_mmmm______tttt _****_s_e_m_,,,, _iiii_nnnn_tttt _****_v_a_l_u_e_))))_;;;;
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  15. DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
  16.      _ssss_eeee_mmmm______gggg_eeee_tttt_vvvv_aaaa_llll_uuuu_eeee obtains the current value of the semaphore located at
  17.      address _s_e_m, and stores it at address _v_a_l_u_e. The returned value should be
  18.      viewed as a snapshot only, useful for debugging.
  19.  
  20.      If the number stored at _v_a_l_u_e is positive, then the semaphore is
  21.      available.  If the number stored at _v_a_l_u_e is zero, then the semaphore is
  22.      not available.  If the number stored at _v_a_l_u_e is negative, then the
  23.      semaphore is not available and the absolute value of the number
  24.      represents the number of processes currently blocked on the semaphore.
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  26.      The address _s_e_m may reside anywhere in the calling processes address
  27.      space, but the process must have read and write access to _s_e_m.
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  29.      _ssss_eeee_mmmm______gggg_eeee_tttt_vvvv_aaaa_llll_uuuu_eeee will fail if the following is true:
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  31.      [EINVAL]    The semaphore located at address _s_e_m is not a valid posix
  32.                  named or unnamed semaphore.
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  34. SSSSEEEEEEEE AAAALLLLSSSSOOOO
  35.      sem_init(3C), sem_destroy(3C), sem_getvalue(3C), sem_post(3C),
  36.      sem_wait(3C), sem_trywait(3C), sem_open(3C), sem_close(3C),
  37.      sem_unlink(3C),
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  39. DDDDIIIIAAAAGGGGNNNNOOOOSSSSTTTTIIIICCCCSSSS
  40.      Upon successful completion, a value of 0 is returned to the calling
  41.      process. Otherwise, a value of -1 is returned and _eeee_rrrr_rrrr_nnnn_oooo is set to
  42.      indicate the error.
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  62.                                                                         PPPPaaaaggggeeee 1111
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