Version 0.2.0 from FTP

git-svn-id: http://svn.digium.com/svn/zaptel/trunk@69 5390a7c7-147a-4af0-8ec9-7488f05a26cb

1 files changed, 130 insertions, 0 deletions

diff --git a/fir.h b/fir.h
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+/*
+ * SpanDSP - a series of DSP components for telephony
+ *
+ * fir.h - General telephony FIR routines
+ *
+ * Written by Steve Underwood <steveu@coppice.org>
+ *
+ * Copyright (C) 2002 Steve Underwood
+ *
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ */
+
+#if !defined(_FIR_H_)
+#define _FIR_H_
+
+typedef struct
+{
+    int taps;
+    int curr_pos;
+    int16_t *coeffs;
+    int16_t *history;
+} fir16_state_t;
+
+typedef struct
+{
+    int taps;
+    int curr_pos;
+    int32_t *coeffs;
+    int16_t *history;
+} fir32_state_t;
+
+static inline void fir16_create (fir16_state_t *fir,
+			         int16_t *coeffs,
+    	    	    	         int taps)
+{
+    fir->taps = taps;
+    fir->curr_pos = taps - 1;
+    fir->coeffs = coeffs;
+    fir->history = MALLOC (taps*sizeof (int16_t));
+    if (fir->history)
+        memset (fir->history, '\0', taps*sizeof (int16_t));
+}
+/*- End of function --------------------------------------------------------*/
+    
+static inline void fir16_free (fir16_state_t *fir)
+{
+    FREE (fir->history);
+}
+/*- End of function --------------------------------------------------------*/
+    
+static inline int16_t fir16 (fir16_state_t *fir, int16_t sample)
+{
+    int i;
+    int offset1;
+    int offset2;
+    int32_t y;
+
+    fir->history[fir->curr_pos] = sample;
+    offset2 = fir->curr_pos + 1;
+    offset1 = fir->taps - offset2;
+    y = 0;
+    for (i = fir->taps - 1;  i >= offset1;  i--)
+        y += fir->coeffs[i]*fir->history[i - offset1];
+    for (  ;  i >= 0;  i--)
+        y += fir->coeffs[i]*fir->history[i + offset2];
+    if (fir->curr_pos <= 0)
+    	fir->curr_pos = fir->taps;
+    fir->curr_pos--;
+    return  y >> 15;
+}
+/*- End of function --------------------------------------------------------*/
+
+static inline void fir32_create (fir32_state_t *fir,
+			         int32_t *coeffs,
+    	    	    	         int taps)
+{
+    fir->taps = taps;
+    fir->curr_pos = taps - 1;
+    fir->coeffs = coeffs;
+    fir->history = MALLOC (taps*sizeof (int16_t));
+    if (fir->history)
+    	memset (fir->history, '\0', taps*sizeof (int16_t));
+}
+/*- End of function --------------------------------------------------------*/
+    
+static inline void fir32_free (fir32_state_t *fir)
+{
+    FREE (fir->history);
+}
+/*- End of function --------------------------------------------------------*/
+    
+static inline int16_t fir32 (fir32_state_t *fir, int16_t sample)
+{
+    int i;
+    int offset1;
+    int offset2;
+    int32_t y;
+
+    fir->history[fir->curr_pos] = sample;
+    offset2 = fir->curr_pos + 1;
+    offset1 = fir->taps - offset2;
+    y = 0;
+    for (i = fir->taps - 1;  i >= offset1;  i--)
+        y += fir->coeffs[i]*fir->history[i - offset1];
+    for (  ;  i >= 0;  i--)
+        y += fir->coeffs[i]*fir->history[i + offset2];
+    if (fir->curr_pos <= 0)
+    	fir->curr_pos = fir->taps;
+    fir->curr_pos--;
+    return  y >> 15;
+}
+/*- End of function --------------------------------------------------------*/
+
+#endif
+/*- End of file ------------------------------------------------------------*/