1al_fixmul(3)               Library Functions Manual               al_fixmul(3)
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NAME

6       al_fixmul
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SYNOPSIS

9              #include <allegro5/allegro.h>
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11              al_fixed al_fixmul(al_fixed x, al_fixed y);
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DESCRIPTION

14       A fixed point value can be multiplied or divided by an integer with the
15       normal * and / operators.  To multiply two fixed point values,  though,
16       you must use this function.
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18       If an overflow occurs, Allegro's errno will be set and the maximum pos‐
19       sible value will be returned, but errno is not cleared if the operation
20       is  successful.   This means that if you are going to test for overflow
21       you should call al_set_errno(0) before calling al_fixmul(3).
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23       Example:
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25                  al_fixed result;
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27                  /* This will put 30000 into `result'. */
28                  result = al_fixmul(al_itofix(10), al_itofix(3000));
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30                  /* But this overflows, and sets errno. */
31                  result = al_fixmul(al_itofix(100), al_itofix(3000));
32                  assert(!al_get_errno());
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RETURN VALUE

35       Returns the clamped result of multiplying x  by  y,  setting  Allegro's
36       errno to ERANGE if there was an overflow.
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SEE ALSO

39       al_fixadd(3), al_fixsub(3), al_fixdiv(3), al_get_errno(3).
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43Allegro reference manual                                          al_fixmul(3)