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Further simplifications to the forward mdct

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This commit is contained in:
Jean-Marc Valin 2008-04-22 09:49:22 +10:00
parent 41880805ab
commit ef0d5f15c7
5 changed files with 28 additions and 32 deletions
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1
libcelt/arch.h
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@ -189,6 +189,7 @@ typedef float celt_mask_t;
#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))

13
libcelt/celt.c
View file

@ -153,29 +153,26 @@ static inline celt_int16_t SIG2INT16(celt_sig_t x)
/** 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];

3
libcelt/fixed_debug.h
View file

@ -44,6 +44,9 @@ static long long celt_mips = 0;
#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))))

3
libcelt/fixed_generic.h
View file

@ -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))

30
libcelt/mdct.c
View file

@ -111,8 +111,11 @@ void mdct_forward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar * r
{
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;
@ -123,27 +126,13 @@ void mdct_forward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar * r
*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++)
{
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;
@ -157,8 +146,11 @@ void mdct_forward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar * r
{
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;