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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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2
libcelt/fixed_generic.h
View file

@ -41,6 +41,8 @@
#define MULT32_32_Q31(a,b) ADD32(ADD32(SHL(MULT16_16(SHR((a),16),SHR((b),16)),1), SHR(MULT16_16SU(SHR((a),16),((b)&0x0000ffff)),15)), SHR(MULT16_16SU(SHR((b),16),((a)&0x0000ffff)),15)) #define MULT32_32_Q31(a,b) ADD32(ADD32(SHL(MULT16_16(SHR((a),16),SHR((b),16)),1), SHR(MULT16_16SU(SHR((a),16),((b)&0x0000ffff)),15)), SHR(MULT16_16SU(SHR((b),16),((a)&0x0000ffff)),15))
#define MULT32_32_Q32(a,b) ADD32(ADD32(MULT16_16(SHR((a),16),SHR((b),16)), SHR(MULT16_16SU(SHR((a),16),((b)&0x0000ffff)),16)), SHR(MULT16_16SU(SHR((b),16),((a)&0x0000ffff)),16))
#define QCONST16(x,bits) ((celt_word16_t)(.5+(x)*(((celt_word32_t)1)<<(bits)))) #define QCONST16(x,bits) ((celt_word16_t)(.5+(x)*(((celt_word32_t)1)<<(bits))))
#define QCONST32(x,bits) ((celt_word32_t)(.5+(x)*(((celt_word32_t)1)<<(bits)))) #define QCONST32(x,bits) ((celt_word32_t)(.5+(x)*(((celt_word32_t)1)<<(bits))))

6
libcelt/mathops.h
View file

@ -164,7 +164,7 @@ static inline celt_word32_t celt_exp2(celt_word16_t x)
return VSHR32(EXTEND32(frac), -integer-2); 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; int i, neg=0;
celt_word16_t n, frac; celt_word16_t n, frac;
@ -174,15 +174,13 @@ static inline celt_word32_t celt_rcp(celt_word16_t x)
neg = 1; neg = 1;
x = NEG16(x); x = NEG16(x);
} }
if (x==0)
return 0;
i = celt_ilog2(x); i = celt_ilog2(x);
n = VSHR32(x,i-16)-SHL32(EXTEND32(3),15); 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], 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]))))))))); MULT16_16_Q15(n, ADD16(C[3], MULT16_16_Q15(n, (C[4])))))))));
if (neg) if (neg)
frac = -frac; frac = -frac;
return SHL32(EXTEND32(frac),16-i); return VSHR32(EXTEND32(frac),i-16);
} }
#endif /* FIXED_POINT */ #endif /* FIXED_POINT */

18
libcelt/vq.c
View file

@ -218,24 +218,24 @@ void alg_quant(celt_norm_t *X, celt_mask_t *W, int N, int K, const celt_norm_t *
if (iy[m][j]*sign < 0) if (iy[m][j]*sign < 0)
continue; continue;
spj = MULT16_16_P14(s, P[j]); spj = MULT16_16_Q14(s, P[j]);
aspj = MULT16_16_P15(alpha, spj); aspj = MULT16_16_Q15(alpha, spj);
/* Updating the sums of the new pulse(s) */ /* Updating the sums of the new pulse(s) */
Rxy = xy[m] + MULT16_16(s,X[j]) - MULT16_16(MULT16_16_P15(alpha,spj),Rxp); Rxy = xy[m] + MULT16_16(s,X[j]) - MULT16_16(MULT16_16_Q15(alpha,spj),Rxp);
Ryy = yy[m] + 2*MULT16_16(s,y[m][j]) + MULT16_16(s,s) +MULT16_16(aspj,MULT16_16_Q14(aspj,Rpp)) - 2*MULT16_32_Q14(aspj,yp[m]) - 2*MULT16_16(s,MULT16_16_Q14(aspj,P[j])); Ryy = yy[m] + 2*MULT16_16(s,y[m][j]) + MULT16_16(s,s) +MULT16_16(aspj,MULT16_16_Q14(aspj,Rpp)) - 2*MULT16_32_Q14(aspj,yp[m]) - 2*MULT16_16(s,MULT16_16_Q14(aspj,P[j]));
Ryp = yp[m] + MULT16_16(spj, SUB16(QCONST16(1.f,14),MULT16_16_Q15(alpha,Rpp))); Ryp = yp[m] + MULT16_16(spj, SUB16(QCONST16(1.f,14),MULT16_16_Q15(alpha,Rpp)));
/* Compute the gain such that ||p + g*y|| = 1 */ /* Compute the gain such that ||p + g*y|| = 1 */
g = MULT32_32_Q31( g = MULT16_32_Q15(
SHL32(celt_sqrt(MULT16_16(ROUND(Ryp,14),ROUND(Ryp,14)) + Ryy - celt_sqrt(MULT16_16(ROUND(Ryp,14),ROUND(Ryp,14)) + Ryy -
MULT16_16(ROUND(Ryy,14),Rpp)) MULT16_16(ROUND(Ryy,14),Rpp))
- ROUND(Ryp,14), 14), - ROUND(Ryp,14),
celt_rcp(ROUND(Ryy,14))); celt_rcp(SHR32(Ryy,12)));
/* Knowing that gain, what's the error: (x-g*y)^2 /* Knowing that gain, what's the error: (x-g*y)^2
(result is negated and we discard x^2 because it's constant) */ (result is negated and we discard x^2 because it's constant) */
/*score = 2.f*g*Rxy - 1.f*g*g*Ryy*NORM_SCALING_1;*/ /*score = 2.f*g*Rxy - 1.f*g*g*Ryy*NORM_SCALING_1;*/
score = 2*MULT16_32_Q14(ROUND(Rxy,14),g) - score = 2*MULT16_32_Q14(ROUND(Rxy,14),g)
MULT16_32_Q14(EXTRACT16(MULT16_32_Q14(ROUND(Ryy,14),g)),g); - MULT16_32_Q14(EXTRACT16(MULT16_32_Q14(ROUND(Ryy,14),g)),g);
if (score>nbest[Lupdate-1]->score) if (score>nbest[Lupdate-1]->score)
{ {