ref: ef0d5f15c767a03a80bf6cea9c6e6e7cfe473168
parent: 41880805ab61f3484a4147ff891111eca10ec8d5
author: Jean-Marc Valin <[email protected]>
date: Tue Apr 22 05:49:22 EDT 2008
Further simplifications to the forward mdct
--- a/libcelt/arch.h
+++ b/libcelt/arch.h
@@ -189,6 +189,7 @@
#define MULT16_32_Q13(a,b) ((a)*(b))
#define MULT16_32_Q14(a,b) ((a)*(b))
#define MULT16_32_Q15(a,b) ((a)*(b))
+#define MULT16_32_Q16(a,b) ((a)*(b))
#define MULT16_32_P15(a,b) ((a)*(b))
#define MULT32_32_Q31(a,b) ((a)*(b))
--- a/libcelt/celt.c
+++ b/libcelt/celt.c
@@ -153,29 +153,26 @@
/** Apply window and compute the MDCT for all sub-frames and all channels in a frame */
static void compute_mdcts(const CELTMode *mode, const celt_word16_t * restrict window, celt_sig_t * restrict in, celt_sig_t * restrict out)
{- int c, N4;
const mdct_lookup *lookup = MDCT(mode);
const int N = FRAMESIZE(mode);
const int C = CHANNELS(mode);
const int overlap = OVERLAP(mode);
- N4 = (N-overlap)>>1;
if (C==1)
{mdct_forward(lookup, in, out, window, overlap);
} else {+ int c;
VARDECL(celt_word32_t, x);
VARDECL(celt_word32_t, tmp);
SAVE_STACK;
- ALLOC(x, 2*N, celt_word32_t);
+ ALLOC(x, N+overlap, celt_word32_t);
ALLOC(tmp, N, celt_word32_t);
for (c=0;c<C;c++)
{int j;
- for (j=0;j<2*N-2*N4;j++)
- x[j+N4] = in[C*j+c];
- CELT_MEMSET(x, 0, N4);
- CELT_MEMSET(x+2*N-N4, 0, N4);
- mdct_forward(lookup, x+N4, tmp, window, overlap);
+ for (j=0;j<N+overlap;j++)
+ x[j] = in[C*j+c];
+ mdct_forward(lookup, x, tmp, window, overlap);
/* Interleaving the sub-frames */
for (j=0;j<N;j++)
out[C*j+c] = tmp[j];
--- a/libcelt/fixed_debug.h
+++ b/libcelt/fixed_debug.h
@@ -44,6 +44,9 @@
#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(SHL32(MULT16_16(SHR((a),16),SHR((b),16)),1), SHR32(MULT16_16SU(SHR((a),16),((b)&0x0000ffff)),15)), SHR(MULT16_16SU(SHR((b),16),((a)&0x0000ffff)),15))
+/** 16x32 multiplication, followed by a 16-bit shift right. Results fits in 32 bits */
+#define MULT16_32_Q16(a,b) ADD32(MULT16_16((a),SHR((b),16)), SHR(MULT16_16SU((a),((b)&0x0000ffff)),16))
+
#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))))
--- a/libcelt/fixed_generic.h
+++ b/libcelt/fixed_generic.h
@@ -38,6 +38,9 @@
/** Multiply a 16-bit signed value by a 16-bit unsigned value. The result is a 32-bit signed value */
#define MULT16_16SU(a,b) ((celt_word32_t)(celt_word16_t)(a)*(celt_word32_t)(celt_uint16_t)(b))
+/** 16x32 multiplication, followed by a 16-bit shift right. Results fits in 32 bits */
+#define MULT16_32_Q16(a,b) ADD32(MULT16_16((a),SHR((b),16)), SHR(MULT16_16SU((a),((b)&0x0000ffff)),16))
+
/** 16x32 multiplication, followed by a 15-bit shift right. Results fits in 32 bits */
#define MULT16_32_Q15(a,b) ADD32(SHL(MULT16_16((a),SHR((b),16)),1), SHR(MULT16_16SU((a),((b)&0x0000ffff)),15))
--- a/libcelt/mdct.c
+++ b/libcelt/mdct.c
@@ -111,8 +111,11 @@
{kiss_fft_scalar re, im;
/* Real part arranged as -d-cR, Imag part arranged as -b+aR*/
- re = -HALF32(MULT16_32_Q15(*wp2, xp1[N2]) + MULT16_32_Q15(*wp1,*xp2));
- im = -HALF32(MULT16_32_Q15(*wp1, *xp1) - MULT16_32_Q15(*wp2, xp2[-N2]));
+ re = -(MULT16_32_Q16(*wp2, xp1[N2]) + MULT16_32_Q16(*wp1,*xp2));
+ im = -(MULT16_32_Q16(*wp1, *xp1) - MULT16_32_Q16(*wp2, xp2[-N2]));
+#ifndef FIXED_POINT
+ re *= .5; im *= .5;
+#endif
xp1+=2;
xp2-=2;
wp1+=2;
@@ -123,20 +126,6 @@
*yp++ = S_MUL(im,t[0]) + S_MUL(re,t[N4]);
t++;
}
- for(;i<N/8;i++)
- {- kiss_fft_scalar re, im;
- /* Real part arranged as -d-cR, Imag part arranged as -b+aR*/
- re = -HALF32(*xp2);
- im = -HALF32(*xp1);
- xp1+=2;
- xp2-=2;
- /* We could remove the HALF32 above and just use MULT16_32_Q16 below
- (MIXED_PRECISION only) */
- *yp++ = S_MUL(re,t[0]) - S_MUL(im,t[N4]);
- *yp++ = S_MUL(im,t[0]) + S_MUL(re,t[N4]);
- t++;
- }
wp1 = window;
wp2 = window+overlap-1;
for(;i<N4-overlap/4;i++)
@@ -143,7 +132,7 @@
{kiss_fft_scalar re, im;
/* Real part arranged as a-bR, Imag part arranged as -c-dR */
- re = HALF32(-*xp2);
+ re = -HALF32(*xp2);
im = -HALF32(*xp1);
xp1+=2;
xp2-=2;
@@ -151,14 +140,17 @@
(MIXED_PRECISION only) */
*yp++ = S_MUL(re,t[0]) - S_MUL(im,t[N4]);
*yp++ = S_MUL(im,t[0]) + S_MUL(re,t[N4]);
- t++;
+ t++;
}
for(;i<N4;i++)
{kiss_fft_scalar re, im;
/* Real part arranged as a-bR, Imag part arranged as -c-dR */
- re = HALF32(MULT16_32_Q15(*wp1, xp1[-N2]) - MULT16_32_Q15(*wp2, *xp2));
- im = -HALF32(MULT16_32_Q15(*wp2, *xp1) + MULT16_32_Q15(*wp1, xp2[N2]));
+ re = (MULT16_32_Q16(*wp1, xp1[-N2]) - MULT16_32_Q16(*wp2, *xp2));
+ im = -(MULT16_32_Q16(*wp2, *xp1) + MULT16_32_Q16(*wp1, xp2[N2]));
+#ifndef FIXED_POINT
+ re *= .5; im *= .5;
+#endif
xp1+=2;
xp2-=2;
wp1+=2;
@@ -189,7 +181,7 @@
fp += 2;
yp1 += 2;
yp2 -= 2;
- t++;
+ t++;
}
}
RESTORE_STACK;