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Using restrict to make it clear there's no aliasing issues in the mdct.

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This commit is contained in:
Jean-Marc Valin 2008-03-22 11:23:57 +11:00
parent a536f77202
commit 3203474732
2 changed files with 13 additions and 13 deletions
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22
libcelt/celt.c
View file

@ -156,7 +156,7 @@ 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 */ /** Apply window and compute the MDCT for all sub-frames and all channels in a frame */
static celt_word32_t compute_mdcts(const mdct_lookup *lookup, const celt_word16_t * restrict window, celt_sig_t *in, celt_sig_t *out, int N, int overlap, int B, int C) static celt_word32_t compute_mdcts(const mdct_lookup *lookup, const celt_word16_t * restrict window, celt_sig_t * restrict in, celt_sig_t * restrict out, int N, int overlap, int B, int C)
{ {
int i, c, N4; int i, c, N4;
celt_word32_t E = 0; celt_word32_t E = 0;
@ -171,12 +171,17 @@ static celt_word32_t compute_mdcts(const mdct_lookup *lookup, const celt_word16_
for (i=0;i<B;i++) for (i=0;i<B;i++)
{ {
int j; int j;
celt_word32_t * restrict x1, * restrict x2;
for (j=0;j<2*N-2*N4;j++) for (j=0;j<2*N-2*N4;j++)
x[j+N4] = in[C*i*N+C*j+c]; x[j+N4] = in[C*i*N+C*j+c];
x1 = x+N4;
x2 = x+2*N-N4-1;
for (j=0;j<overlap;j++) for (j=0;j<overlap;j++)
{ {
x[j+N4] = MULT16_32_Q15(window[j],x[j+N4]); *x1 = MULT16_32_Q15(window[j],*x1);
x[2*N-j-N4-1] = MULT16_32_Q15(window[j],x[2*N-j-N4-1]); *x2 = MULT16_32_Q15(window[j],*x2);
x1++;
x2--;
} }
for (j=0;j<N4;j++) for (j=0;j<N4;j++)
{ {
@ -196,7 +201,7 @@ static celt_word32_t compute_mdcts(const mdct_lookup *lookup, const celt_word16_
} }
/** Compute the IMDCT and apply window for all sub-frames and all channels in a frame */ /** Compute the IMDCT and apply window for all sub-frames and all channels in a frame */
static void compute_inv_mdcts(const mdct_lookup *lookup, const celt_word16_t * restrict window, celt_sig_t *X, celt_sig_t *out_mem, celt_sig_t *mdct_overlap, int N, int overlap, int B, int C) static void compute_inv_mdcts(const mdct_lookup *lookup, const celt_word16_t * restrict window, celt_sig_t *X, celt_sig_t * restrict out_mem, celt_sig_t * restrict mdct_overlap, int N, int overlap, int B, int C)
{ {
int i, c, N4; int i, c, N4;
VARDECL(celt_word32_t, x); VARDECL(celt_word32_t, x);
@ -217,16 +222,11 @@ static void compute_inv_mdcts(const mdct_lookup *lookup, const celt_word16_t * r
/* The first and last part would need to be set to zero if we actually /* The first and last part would need to be set to zero if we actually
wanted to use them. */ wanted to use them. */
for (j=0;j<overlap;j++) for (j=0;j<overlap;j++)
{ out_mem[C*(MAX_PERIOD+(i-B)*N)+C*j+c] = 2*(mdct_overlap[C*j+c]+MULT16_32_Q15(window[j],x[j+N4]));
x[j+N4] = MULT16_32_Q15(window[j],x[j+N4]);
x[2*N-j-N4-1] = MULT16_32_Q15(window[j],x[2*N-j-N4-1]);
}
for (j=0;j<overlap;j++) for (j=0;j<overlap;j++)
out_mem[C*(MAX_PERIOD+(i-B)*N)+C*j+c] = 2*(x[N4+j]+mdct_overlap[C*j+c]); mdct_overlap[C*(overlap-j-1)+c] = MULT16_32_Q15(window[j],x[2*N-j-N4-1]);
for (j=0;j<2*N4;j++) for (j=0;j<2*N4;j++)
out_mem[C*(MAX_PERIOD+(i-B)*N)+C*(j+overlap)+c] = 2*x[j+N4+overlap]; out_mem[C*(MAX_PERIOD+(i-B)*N)+C*(j+overlap)+c] = 2*x[j+N4+overlap];
for (j=0;j<overlap;j++)
mdct_overlap[C*j+c] = x[N+N4+j];
} }
} }
RESTORE_STACK; RESTORE_STACK;

4
libcelt/mdct.c
View file

@ -86,7 +86,7 @@ void mdct_clear(mdct_lookup *l)
celt_free(l->trig); celt_free(l->trig);
} }
void mdct_forward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar *out) void mdct_forward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar * restrict out)
{ {
int i; int i;
int N, N2, N4; int N, N2, N4;
@ -131,7 +131,7 @@ void mdct_forward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar *ou
} }
void mdct_backward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar *out) void mdct_backward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar * restrict out)
{ {
int i; int i;
int N, N2, N4; int N, N2, N4;