1 02/02/84  signal_
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 4 Entry points in signal_:
 5    (List is generated by the help command)
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 8 :Entry: signal_: 02/02/84  signal_
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10 
11 Function: signals the occurrence of a given condition.  A description
12 of the condition mechanism and the way in which a handler is invoked
13 by the signal_ subroutine is given in the Programmer's Reference
14 Manual.
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16 
17 Syntax:
18 declare signal_ entry options (variable);
19 call signal_ (name, mc_ptr, info_ptr, wc_ptr);
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21 
22 Arguments:
23 name
24    is the name (declared as a nonvarying character string) of the
25    condition to be signalled.  (Input)
26 mc_ptr
27    is a pointer (declared as an aligned pointer) to the machine
28    conditions at the time the condition was raised.  This argument is
29    used by system programs only in order to signal hardware faults.  In
30    user programs, this argument should be null if a third argument is
31    supplied.  This argument is optional.  (Input)
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33 
34 info_ptr
35    is a pointer (declared as an aligned pointer) to information
36    relating to the condition being raised.  The structure of the
37    information is dependent upon the condition being signalled;
38    however, conditions raised with the same name should provide the
39    information in the same structure.  All structures must begin with a
40    standard header.  The format for the header as well as the
41    structures provided with system conditions are described in the
42    Programmer's Reference Manual.  This argument is intended for use in
43    signalling conditions other than hardware faults.  This argument is
44    optional.  (Input)
45 
46 
47 wc_ptr
48    is a pointer (declared as an aligned pointer) to the machine
49    conditions at the time a lower ring was entered to process a fault.
50    This argument is used only by the system and only in the case where
51    a condition that occurred in a lower ring is being signalled in the
52    outer ring and when the lower ring has been entered to process a
53    fault occurring in the outer ring.  This argument is optional.
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56 Notes:  If the signal_ subroutine returns to its caller, indicating
57 that the handler has returned to it, the calling procedure should retry
58 the operation that caused the condition to be signalled.
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60 The PL/I signal statement differs from the signal_ subroutine in that
61 the above parameters cannot be provided in the signal statement.  Also,
62 for PL/I-defined conditions, a call to the signal_ subroutine is not
63 equivalent to a PL/I signal statement since information about these
64 conditions is kept internally.