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Defined the celt_rcp() reciprocal approximation

--- a/libcelt/mathops.h

+++ b/libcelt/mathops.h

@@ -44,8 +44,8 @@

 #define celt_exp exp

 #define celt_cos_norm(x) (cos((.5f*M_PI)*(x)))

 #define celt_atan atan

+#define celt_rcp(x) (1.f/(x))

-

 #endif

@@ -161,8 +161,25 @@

    return VSHR32(EXTEND32(frac), -integer-2);

 }

+static inline celt_word32_t celt_rcp(celt_word16_t x)

+{

+   int i, neg=0;

+   celt_word16_t n, frac;

+   const celt_word16_t C[4] = {10905, -3624, 1362, -470};

+   if (x<0)

+   {

+      neg = 1;

+      x = NEG16(x);

+   }

+   if (x==0)

+      return 0;

+   i = celt_ilog2(x);

+   n = VSHR32(x,i-15)-32768-16384;

+   frac = ADD16(C[0], MULT16_16_Q14(n, ADD16(C[1], MULT16_16_Q14(n, ADD16(C[2], MULT16_16_Q14(n, (C[3])))))));

+   return neg ? -SHL32(EXTEND32(frac),17-i) : SHL32(EXTEND32(frac),17-i);

+}

-#endif

+#endif /* FIXED_POINT */

-#endif

+#endif /* MATHOPS_H */