1 files changed, 125 insertions, 0 deletions
diff --git a/libcelt/plc.c b/libcelt/plc.c
new file mode 100644
index 0000000..6b2f3e0
--- /dev/null
+++ b/libcelt/plc.c
@@ -0,0 +1,125 @@
+
+
+
+
+celt_word32 _celt_lpc(
+celt_word16       *lpc, /* out: [0...p-1] LPC coefficients      */
+const celt_word16 *ac,  /* in:  [0...p] autocorrelation values  */
+int          p
+)
+{
+   int i, j;  
+   celt_word16 r;
+   celt_word16 error = ac[0];
+
+   if (ac[0] == 0)
+   {
+      for (i = 0; i < p; i++)
+         lpc[i] = 0;
+      return 0;
+   }
+   
+   for (i = 0; i < p; i++) {
+      
+      /* Sum up this iteration's reflection coefficient */
+      celt_word32 rr = NEG32(SHL32(EXTEND32(ac[i + 1]),13));
+      for (j = 0; j < i; j++) 
+         rr = SUB32(rr,MULT16_16(lpc[j],ac[i - j]));
+#ifdef FIXED_POINT
+      r = DIV32_16(rr+PSHR32(error,1),ADD16(error,8));
+#else
+      r = rr/(error+.003*ac[0]);
+#endif
+      /*  Update LPC coefficients and total error */
+      lpc[i] = r;
+      for (j = 0; j < i>>1; j++) 
+      {
+         celt_word16 tmp  = lpc[j];
+         lpc[j]     = MAC16_16_P13(lpc[j],r,lpc[i-1-j]);
+         lpc[i-1-j] = MAC16_16_P13(lpc[i-1-j],r,tmp);
+      }
+      if (i & 1) 
+         lpc[j] = MAC16_16_P13(lpc[j],lpc[j],r);
+      
+      error = SUB16(error,MULT16_16_Q13(r,MULT16_16_Q13(error,r)));
+   }
+   return error;
+}
+
+void fir(const celt_word16 *x,
+         const celt_word16 *num,
+         celt_word16 *y,
+         int N,
+         int ord,
+         celt_word32 *mem)
+{
+   int i,j;
+
+   for (i=0;i<N;i++)
+   {
+      float sum = x[i];
+      for (j=0;j<ord;j++)
+      {
+         sum += num[j]*mem[j];
+      }
+      for (j=ord-1;j>=1;j--)
+      {
+         mem[j]=mem[j-1];
+      }
+      mem[0] = x[i];
+      y[i] = sum;
+   }
+}
+
+void iir(const celt_word16 *x,
+         const celt_word16 *den,
+         celt_word16 *y,
+         int N,
+         int ord,
+         celt_word32 *mem)
+{
+   int i,j;
+   for (i=0;i<N;i++)
+   {
+      float sum = x[i];
+      for (j=0;j<ord;j++)
+      {
+         sum -= den[j]*mem[j];
+      }
+      for (j=ord-1;j>=1;j--)
+      {
+         mem[j]=mem[j-1];
+      }
+      mem[0] = sum;
+      y[i] = sum;
+   }
+}
+
+void _celt_autocorr(
+                   const celt_word16 *x,   /*  in: [0...n-1] samples x   */
+                   float       *ac,  /* out: [0...lag-1] ac values */
+                   const float       *window,
+                   int          overlap,
+                   int          lag, 
+                   int          n
+                  )
+{
+   float d;
+   int i;
+   float xx[n];
+   for (i=0;i<n;i++)
+      xx[i] = x[i];
+   for (i=0;i<overlap;i++)
+   {
+      xx[i] *= window[i];
+      xx[n-i-1] *= window[i];
+   }
+   while (lag>=0)
+   {
+      for (i = lag, d = 0; i < n; i++) 
+         d += x[i] * x[i-lag];
+      ac[lag] = d;
+      lag--;
+   }
+   ac[0] += 10;
+}