Commit d857ac48 authored by Jean-Marc Valin's avatar Jean-Marc Valin
Browse files

Using reciprocal approximation instead of full 32-bit division in alg_quant()

parent 980ad384
......@@ -89,11 +89,6 @@ struct kiss_fft_state{
#ifdef MIXED_PRECISION
#undef MULT16_32_Q15
#define MULT16_16SU(a,b) ((celt_word32_t)(celt_word16_t)(a)*(celt_word32_t)(celt_uint16_t)(b))
/*#define MULT16_32_Q15(a,b) ADD32(MULT16_16((a),SHR((b),15)), SHR(MULT16_16((a),((b)&0x00007fff)),15))*/
#define MULT16_32_Q15(a,b) ADD32(SHL(MULT16_16((a),SHR((b),16)),1), SHR(MULT16_16SU((a),((b)&0x0000ffff)),15))
# define S_MUL(a,b) MULT16_32_Q15(b, a)
# define C_MUL(m,a,b) \
......
......@@ -177,6 +177,8 @@ typedef float celt_mask_t;
#define MULT16_32_Q15(a,b) ((a)*(b))
#define MULT16_32_P15(a,b) ((a)*(b))
#define MULT32_32_Q31(a,b) ((a)*(b))
#define MAC16_32_Q11(c,a,b) ((c)+(a)*(b))
#define MAC16_32_Q15(c,a,b) ((c)+(a)*(b))
......
......@@ -41,6 +41,9 @@
static long long celt_mips = 0;
#define MIPS_INC celt_mips++,
#define MULT16_16SU(a,b) ((celt_word32_t)(celt_word16_t)(a)*(celt_word32_t)(celt_uint16_t)(b))
#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 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))))
......
......@@ -35,6 +35,13 @@
#ifndef FIXED_GENERIC_H
#define FIXED_GENERIC_H
#define MULT16_16SU(a,b) ((celt_word32_t)(celt_word16_t)(a)*(celt_word32_t)(celt_uint16_t)(b))
#define MULT16_32_Q15(a,b) ADD32(SHL(MULT16_16((a),SHR((b),16)),1), SHR(MULT16_16SU((a),((b)&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 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))))
......@@ -81,7 +88,6 @@
#define MAC16_32_Q11(c,a,b) ADD32(c,ADD32(MULT16_16((a),SHR((b),11)), SHR(MULT16_16((a),((b)&0x000007ff)),11)))
#define MULT16_32_P15(a,b) ADD32(MULT16_16((a),SHR((b),15)), PSHR(MULT16_16((a),((b)&0x00007fff)),15))
#define MULT16_32_Q15(a,b) ADD32(MULT16_16((a),SHR((b),15)), SHR(MULT16_16((a),((b)&0x00007fff)),15))
#define MAC16_32_Q15(c,a,b) ADD32(c,ADD32(MULT16_16((a),SHR((b),15)), SHR(MULT16_16((a),((b)&0x00007fff)),15)))
......
......@@ -226,9 +226,12 @@ void alg_quant(celt_norm_t *X, celt_mask_t *W, int N, int K, const celt_norm_t *
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 */
g = DIV32(SHL32(celt_sqrt(MULT16_16(ROUND(Ryp,14),ROUND(Ryp,14)) + Ryy - MULT16_16(ROUND(Ryy,14),Rpp)) - ROUND(Ryp,14),14),ROUND(Ryy,14));
/* Knowing that gain, what the error: (x-g*y)^2
g = MULT32_32_Q31(
SHL32(celt_sqrt(MULT16_16(ROUND(Ryp,14),ROUND(Ryp,14)) + Ryy -
MULT16_16(ROUND(Ryy,14),Rpp))
- ROUND(Ryp,14), 14),
celt_rcp(ROUND(Ryy,14)));
/* Knowing that gain, what's the error: (x-g*y)^2
(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*MULT16_32_Q14(ROUND(Rxy,14),g) -
......
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