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[cairo-fixed] Implement _cairo_fixed_mul_div()

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Computes a*b/c where a,b,c are cairo_fixed_t.
This commit is contained in:
Behdad Esfahbod 2008-05-15 20:02:33 -04:00
parent 84606a900f
commit b355ac7a9f
1 changed files with 11 additions and 0 deletions
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11
src/cairo-fixed-private.h
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@ -226,6 +226,17 @@ _cairo_fixed_mul (cairo_fixed_t a, cairo_fixed_t b)
return _cairo_int64_to_int32(_cairo_int64_rsl (temp, CAIRO_FIXED_FRAC_BITS));
}
/* computes a * b / c */
static inline cairo_fixed_t
_cairo_fixed_mul_div (cairo_fixed_t a, cairo_fixed_t b, cairo_fixed_t c)
{
cairo_int64_t ab = _cairo_int32x32_64_mul (a, b);
cairo_int64_t c64 = _cairo_int32_to_int64 (c);
cairo_int64_t quo = _cairo_int64_divrem (ab, c64).quo;
return _cairo_int64_to_int32(quo);
}
#else
# error Please define multiplication and other operands for your fixed-point type size
#endif