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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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4
libcelt/bands.c
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@ -126,7 +126,7 @@ void normalise_bands(const CELTMode *m, const celt_sig_t *freq, celt_norm_t *X,
shift = celt_zlog2(bank[i*C+c])-13;
E = VSHR32(bank[i*C+c], shift);
if (E>0)
g = DIV32_16(QCONST32(1.f,28),MULT16_16_Q14(E,sqrtC_1[C-1]));
g = EXTRACT16(celt_div(QCONST32(1.f,28),MULT16_16_Q14(E,sqrtC_1[C-1])));
else
g = 0;
for (j=B*eBands[i];j<B*eBands[i+1];j++)
@ -257,7 +257,7 @@ void compute_pitch_gain(const CELTMode *m, const celt_norm_t *X, const celt_norm
residual doesn't quantise well */
Sxy = MULT16_32_Q15(QCONST16(.9f, 15), Sxy);
/* gain = Sxy/Sxx */
gains[i] = DIV32_16(Sxy,ADD32(SHR32(Sxx, PGAIN_SHIFT),EPSILON));
gains[i] = EXTRACT16(celt_div(Sxy,ADD32(SHR32(Sxx, PGAIN_SHIFT),EPSILON)));
/*printf ("%f ", 1-sqrt(1-gain*gain));*/
}
/*if(rand()%10==0)

3
libcelt/mathops.h
View file

@ -45,6 +45,7 @@
#define celt_cos_norm(x) (cos((.5f*M_PI)*(x)))
#define celt_atan atan
#define celt_rcp(x) (1.f/(x))
#define celt_div(a,b) ((a)/(b))
#endif
@ -202,6 +203,8 @@ static inline celt_word32_t celt_rcp(celt_word32_t x)
return VSHR32(EXTEND32(frac),i-16);
}
#define celt_div(a,b) MULT32_32_Q31(a,celt_rcp(b))
#endif /* FIXED_POINT */

6
libcelt/quant_bands.c
View file

@ -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++)

2
libcelt/vq.c
View file

@ -378,7 +378,7 @@ void intra_prediction(celt_norm_t *x, celt_mask_t *W, int N, int K, celt_norm_t
xy = MAC16_16(xy, x[j], Y[i+N-j-1]);
yy = MAC16_16(yy, Y[i+N-j-1], Y[i+N-j-1]);
}
score = DIV32(MULT16_16(ROUND16(xy,14),ROUND16(xy,14)), ROUND16(yy,14));
score = celt_div(MULT16_16(ROUND16(xy,14),ROUND16(xy,14)), ROUND16(yy,14));
if (score > best_score)
{
best_score = score;