1fixadd(3)                       Allegro manual                       fixadd(3)
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NAME

6       fixadd  -  Safe  function to add fixed point numbers clamping overflow.
7       Allegro game programming library.
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SYNOPSIS

10       #include <allegro.h>
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13       fixed fixadd(fixed x, fixed y);
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DESCRIPTION

16       Although fixed point numbers can be added with the normal  '+'  integer
17       operator,  that  doesn't  provide  any  protection against overflow. If
18       overflow is a problem, you should use  this  function  instead.  It  is
19       slower  than using integer operators, but if an overflow occurs it will
20       set `errno' and clamp the result, rather than  just  letting  it  wrap.
21       Example:
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23          fixed result;
24          /* This will put 5035 into `result'. */
25          result = fixadd(itofix(5000), itofix(35));
26          /* Sets `errno' and puts -32768 into `result'. */
27          result = fixadd(itofix(-31000), itofix(-3000));
28          ASSERT(!errno); /* This will fail. */
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RETURN VALUE

31       Returns  the  clamped  result  of adding `x' to `y', setting `errno' to
32       ERANGE if there was an overflow.
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SEE ALSO

36       fixsub(3), fixmul(3), fixdiv(3)
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40Allegro                          version 4.2.2                       fixadd(3)
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