shithub: opus

Info  •  Files  •  Log  •  Branches

Implements fixed-point silk_LPC_analysis_filter() in terms of celt_fir()

Saves 2.5% on ARM without any asm. The float build still uses the old
code because celt_fir() then becomes a float function.

--- a/celt/arch.h

+++ b/celt/arch.h

@@ -163,6 +163,7 @@

 #define SHR(a,shift)    (a)

 #define SHL(a,shift)    (a)

 #define SATURATE(x,a)   (x)

+#define SATURATE16(x)   (x)

 #define ROUND16(a,shift)  (a)

 #define HALF16(x)       (.5f*(x))

--- a/celt/celt_lpc.c

+++ b/celt/celt_lpc.c

@@ -118,18 +118,17 @@

       {

          sum = MAC16_16(sum,rnum[j],x[i+j]);

       }

-      _y[i] = ROUND16(sum, SIG_SHIFT);

+      _y[i] = SATURATE16(PSHR32(sum, SIG_SHIFT));

    }

 #else

-   celt_assert((ord&3)==0);

    for (i=0;i<N-3;i+=4)

    {

       opus_val32 sum[4]={0,0,0,0};

       xcorr_kernel(rnum, x+i, sum, ord);

-      _y[i  ] = ADD16(_x[i  ], ROUND16(sum[0], SIG_SHIFT));

-      _y[i+1] = ADD16(_x[i+1], ROUND16(sum[1], SIG_SHIFT));

-      _y[i+2] = ADD16(_x[i+2], ROUND16(sum[2], SIG_SHIFT));

-      _y[i+3] = ADD16(_x[i+3], ROUND16(sum[3], SIG_SHIFT));

+      _y[i  ] = SATURATE16(ADD32(EXTEND32(_x[i  ]), PSHR32(sum[0], SIG_SHIFT)));

+      _y[i+1] = SATURATE16(ADD32(EXTEND32(_x[i+1]), PSHR32(sum[1], SIG_SHIFT)));

+      _y[i+2] = SATURATE16(ADD32(EXTEND32(_x[i+2]), PSHR32(sum[2], SIG_SHIFT)));

+      _y[i+3] = SATURATE16(ADD32(EXTEND32(_x[i+3]), PSHR32(sum[3], SIG_SHIFT)));

    }

    for (;i<N;i++)

    {

@@ -136,7 +135,7 @@

       opus_val32 sum = 0;

       for (j=0;j<ord;j++)

          sum = MAC16_16(sum,rnum[j],x[i+j]);

-      _y[i] = ADD16(_x[i  ], ROUND16(sum, SIG_SHIFT));

+      _y[i] = SATURATE16(ADD32(EXTEND32(_x[i]), PSHR32(sum, SIG_SHIFT)));

    }

 #endif

    RESTORE_STACK;

--- a/celt/fixed_generic.h

+++ b/celt/fixed_generic.h

@@ -84,6 +84,8 @@

 #define PSHR(a,shift) (SHR((a)+((EXTEND32(1)<<((shift))>>1)),shift))

 #define SATURATE(x,a) (((x)>(a) ? (a) : (x)<-(a) ? -(a) : (x)))

+#define SATURATE16(x) (EXTRACT16((x)>32767 ? 32767 : (x)<-32768 ? -32768 : (x)))

+

 /** Shift by a and round-to-neareast 32-bit value. Result is a 16-bit value */

 #define ROUND16(x,a) (EXTRACT16(PSHR32((x),(a))))

 /** Divide by two */

--- a/silk/LPC_analysis_filter.c

+++ b/silk/LPC_analysis_filter.c

@@ -30,6 +30,7 @@

 #endif

 #include "SigProc_FIX.h"

+#include "celt_lpc.h"

 /*******************************************/

 /* LPC analysis filter                     */

@@ -46,14 +47,33 @@

     const opus_int32            d                   /* I    Filter order                                                */

 )

 {

-    opus_int         ix, j;

+    opus_int   j;

+#ifdef FIXED_POINT

+    opus_int16 mem[SILK_MAX_ORDER_LPC];

+    opus_int16 num[SILK_MAX_ORDER_LPC];

+#else

+    int ix;

     opus_int32       out32_Q12, out32;

     const opus_int16 *in_ptr;

+#endif

     silk_assert( d >= 6 );

     silk_assert( (d & 1) == 0 );

     silk_assert( d <= len );

+#ifdef FIXED_POINT

+    silk_assert( d <= SILK_MAX_ORDER_LPC );

+    for ( j = 0; j < d; j++ ) {

+        num[ j ] = -B[ j ];

+    }

+    for (j=0;j<d;j++) {

+        mem[ j ] = in[ d - j - 1 ];

+    }

+    celt_fir( in + d, num, out + d, len - d, d, mem );

+    for ( j = 0; j < d; j++ ) {

+        out[ j ] = 0;

+    }

+#else

     for( ix = d; ix < len; ix++ ) {

         in_ptr = &in[ ix - 1 ];

@@ -82,4 +102,5 @@

     /* Set first d output samples to zero */

     silk_memset( out, 0, d * sizeof( opus_int16 ) );

+#endif

 }