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fixed-point: defined HALF32() and used it for the forward mdct.

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This commit is contained in:
Jean-Marc Valin 2008-03-07 17:50:45 +11:00
parent 957a4fae0e
commit c209c342bf
4 changed files with 12 additions and 9 deletions
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1
libcelt/arch.h
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@ -159,6 +159,7 @@ typedef float celt_mask_t;
#define SATURATE(x,a) (x)
#define ROUND(a,shift) (a)
#define HALF32(x) (.5f*(x))
#define ADD16(a,b) ((a)+(b))
#define SUB16(a,b) ((a)-(b))

1
libcelt/fixed_debug.h
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@ -172,6 +172,7 @@ static inline int SHL32(long long a, int shift)
#define SATURATE32(x,a) (((x)>(a) ? (a) : (x)<-(a) ? -(a) : (x)))
#define ROUND(x,a) (EXTRACT16(PSHR32((x),(a))))
#define HALF32(x) (SHR32(x,1))
//#define SHR(a,shift) ((a) >> (shift))
//#define SHL(a,shift) ((a) << (shift))

1
libcelt/fixed_generic.h
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@ -58,6 +58,7 @@
#define SATURATE(x,a) (((x)>(a) ? (a) : (x)<-(a) ? -(a) : (x)))
#define ROUND(x,a) (EXTRACT16(PSHR32((x),(a))))
#define HALF32(x) (SHR32(x,1))
#define ADD16(a,b) ((celt_word16_t)((celt_word16_t)(a)+(celt_word16_t)(b)))
#define SUB16(a,b) ((celt_word16_t)(a)-(celt_word16_t)(b))

8
libcelt/mdct.c
View file

@ -104,8 +104,8 @@ void mdct_forward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar *ou
{
kiss_fft_scalar re, im;
/* Real part arranged as -d-cR, Imag part arranged as -b+aR*/
re = -.5*(in[N2+N4+2*i] + in[N2+N4-2*i-1]);
im = -.5*(in[N4+2*i] - in[N4-2*i-1]);
re = -HALF32(in[N2+N4+2*i] + in[N2+N4-2*i-1]);
im = -HALF32(in[N4+2*i] - in[N4-2*i-1]);
out[2*i] = S_MUL(re,l->trig[i]) - S_MUL(im,l->trig[i+N4]);
out[2*i+1] = S_MUL(im,l->trig[i]) + S_MUL(re,l->trig[i+N4]);
}
@ -113,8 +113,8 @@ void mdct_forward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar *ou
{
kiss_fft_scalar re, im;
/* Real part arranged as a-bR, Imag part arranged as -c-dR */
re = .5*(in[2*i-N4] - in[N2+N4-2*i-1]);
im = -.5*(in[N4+2*i] + in[N+N4-2*i-1]);
re = HALF32(in[2*i-N4] - in[N2+N4-2*i-1]);
im = -HALF32(in[N4+2*i] + in[N+N4-2*i-1]);
out[2*i] = S_MUL(re,l->trig[i]) - S_MUL(im,l->trig[i+N4]);
out[2*i+1] = S_MUL(im,l->trig[i]) + S_MUL(re,l->trig[i+N4]);
}