libsndfile compiling.

[Faustine.git] / interpretor / lib / src / libsndfile-1.0.25 / src / GSM610 / preprocess.c

diff --git a/interpretor/lib/src/libsndfile-1.0.25/src/GSM610/preprocess.c b/interpretor/lib/src/libsndfile-1.0.25/src/GSM610/preprocess.c
new file mode 100644 (file)
index 0000000..723e226
--- /dev/null
+++ b/interpretor/lib/src/libsndfile-1.0.25/src/GSM610/preprocess.c
@@ -0,0 +1,105 @@
+/*
+ * Copyright 1992 by Jutta Degener and Carsten Bormann, Technische
+ * Universitaet Berlin.  See the accompanying file "COPYRIGHT" for
+ * details.  THERE IS ABSOLUTELY NO WARRANTY FOR THIS SOFTWARE.
+ */
+
+#include       <stdio.h>
+#include       <assert.h>
+
+#include "gsm610_priv.h"
+
+/*     4.2.0 .. 4.2.3  PREPROCESSING SECTION
+ *  
+ *     After A-law to linear conversion (or directly from the
+ *     Ato D converter) the following scaling is assumed for
+ *     input to the RPE-LTP algorithm:
+ *
+ *      in:  0.1.....................12
+ *          S.v.v.v.v.v.v.v.v.v.v.v.v.*.*.*
+ *
+ *     Where S is the sign bit, v a valid bit, and * a "don't care" bit.
+ *     The original signal is called sop[..]
+ *
+ *      out:   0.1................... 12 
+ *          S.S.v.v.v.v.v.v.v.v.v.v.v.v.0.0
+ */
+
+
+void Gsm_Preprocess (
+       struct gsm_state * S,
+       word             * s,
+       word             * so )         /* [0..159]     IN/OUT  */
+{
+
+       word       z1 = S->z1;
+       longword L_z2 = S->L_z2;
+       word       mp = S->mp;
+
+       word            s1;
+       longword      L_s2;
+
+       longword      L_temp;
+
+       word            msp, lsp;
+       word            SO;
+
+       register int            k = 160;
+
+       while (k--) {
+
+       /*  4.2.1   Downscaling of the input signal
+        */
+               SO = SASR_W( *s, 3 ) << 2;
+               s++;
+
+               assert (SO >= -0x4000); /* downscaled by     */
+               assert (SO <=  0x3FFC); /* previous routine. */
+
+
+       /*  4.2.2   Offset compensation
+        * 
+        *  This part implements a high-pass filter and requires extended
+        *  arithmetic precision for the recursive part of this filter.
+        *  The input of this procedure is the array so[0...159] and the
+        *  output the array sof[ 0...159 ].
+        */
+               /*   Compute the non-recursive part
+                */
+
+               s1 = SO - z1;                   /* s1 = gsm_sub( *so, z1 ); */
+               z1 = SO;
+
+               assert(s1 != MIN_WORD);
+
+               /*   Compute the recursive part
+                */
+               L_s2 = s1;
+               L_s2 <<= 15;
+
+               /*   Execution of a 31 bv 16 bits multiplication
+                */
+
+               msp = SASR_L( L_z2, 15 );
+               lsp = L_z2-((longword)msp<<15); /* gsm_L_sub(L_z2,(msp<<15)); */
+
+               L_s2  += GSM_MULT_R( lsp, 32735 );
+               L_temp = (longword)msp * 32735; /* GSM_L_MULT(msp,32735) >> 1;*/
+               L_z2   = GSM_L_ADD( L_temp, L_s2 );
+
+               /*    Compute sof[k] with rounding
+                */
+               L_temp = GSM_L_ADD( L_z2, 16384 );
+
+       /*   4.2.3  Preemphasis
+        */
+
+               msp   = GSM_MULT_R( mp, -28180 );
+               mp    = SASR_L( L_temp, 15 );
+               *so++ = GSM_ADD( mp, msp );
+       }
+
+       S->z1   = z1;
+       S->L_z2 = L_z2;
+       S->mp   = mp;
+}