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fixed-point: added cheap celt_div() division using a reciprocal

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This commit is contained in:
Jean-Marc Valin 2008-03-22 21:17:45 +11:00
parent ba238d8793
commit 2282383434
4 changed files with 9 additions and 6 deletions
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6
libcelt/quant_bands.c
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@ -106,7 +106,7 @@ static void quant_energy_mono(const CELTMode *m, celt_ener_t *eBands, celt_word1
celt_word16_t f; /* Q8 */
celt_word16_t mean = MULT16_16_Q15(Q15ONE-coef,eMeans[i]);
x = amp2dB(eBands[i]);
f = DIV32_16(SHL32(EXTEND32(x-mean-MULT16_16_Q15(coef,oldEBands[i])-prev),8),base_resolution);
f = EXTRACT16(celt_div(SHL32(EXTEND32(x-mean-MULT16_16_Q15(coef,oldEBands[i])-prev),8),base_resolution));
#ifdef FIXED_POINT
/* Rounding to nearest integer here is really important! */
qi = (f+128)>>8;
@ -149,7 +149,7 @@ static void quant_energy_mono(const CELTMode *m, celt_ener_t *eBands, celt_word1
if (q2 > frac[i]-1)
q2 = frac[i]-1;
ec_enc_uint(enc, q2, frac[i]);
offset = DIV32_16(SHL16(q2,8)+QCONST16(.5,8),frac[i])-QCONST16(.5f,8);
offset = EXTRACT16(celt_div(SHL16(q2,8)+QCONST16(.5,8),frac[i])-QCONST16(.5f,8));
oldEBands[i] += PSHR32(MULT16_16(DB_SCALING*6,offset),8);
/*printf ("%f ", error[i] - offset);*/
}
@ -199,7 +199,7 @@ static void unquant_energy_mono(const CELTMode *m, celt_ener_t *eBands, celt_wor
if (ec_dec_tell(dec, 0) - bits +EC_ILOG(frac[i])> budget)
break;
q2 = ec_dec_uint(dec, frac[i]);
offset = DIV32_16(SHL16(q2,8)+QCONST16(.5,8),frac[i])-QCONST16(.5f,8);
offset = EXTRACT16(celt_div(SHL16(q2,8)+QCONST16(.5,8),frac[i])-QCONST16(.5f,8));
oldEBands[i] += PSHR32(MULT16_16(DB_SCALING*6,offset),8);
}
for (i=0;i<m->nbEBands;i++)