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fixed-point: simplifying the arithmetic in alg_quant()

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This commit is contained in:
Jean-Marc Valin 2008-03-13 11:18:15 +11:00
parent 3ec78b173b
commit 19ae9fc944
3 changed files with 14 additions and 14 deletions
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6
libcelt/mathops.h
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@ -164,7 +164,7 @@ static inline celt_word32_t celt_exp2(celt_word16_t x)
return VSHR32(EXTEND32(frac), -integer-2);
}
static inline celt_word32_t celt_rcp(celt_word16_t x)
static inline celt_word32_t celt_rcp(celt_word32_t x)
{
int i, neg=0;
celt_word16_t n, frac;
@ -174,15 +174,13 @@ static inline celt_word32_t celt_rcp(celt_word16_t x)
neg = 1;
x = NEG16(x);
}
if (x==0)
return 0;
i = celt_ilog2(x);
n = VSHR32(x,i-16)-SHL32(EXTEND32(3),15);
frac = ADD16(C[0], MULT16_16_Q15(n, ADD16(C[1], MULT16_16_Q15(n, ADD16(C[2],
MULT16_16_Q15(n, ADD16(C[3], MULT16_16_Q15(n, (C[4])))))))));
if (neg)
frac = -frac;
return SHL32(EXTEND32(frac),16-i);
return VSHR32(EXTEND32(frac),i-16);
}
#endif /* FIXED_POINT */