--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/spandsp-0.0.3/spandsp-0.0.3/src/spandsp/fir.h	Fri Jun 25 16:00:21 2010 +0200
@@ -0,0 +1,369 @@
+/*
+ * 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 version 2, as
+ * published by the Free Software Foundation.
+ *
+ * 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.
+ *
+ * $Id: fir.h,v 1.8 2006/10/24 13:45:28 steveu Exp $
+ */
+
+/*! \page fir_page FIR filtering
+\section fir_page_sec_1 What does it do?
+???.
+
+\section fir_page_sec_2 How does it work?
+???.
+*/
+
+#if !defined(_FIR_H_)
+#define _FIR_H_
+
+/* 
+   Blackfin NOTES & IDEAS:
+
+   A simple dot product function is used to implement the filter.  This performs
+   just one MAC/cycle which is inefficient but was easy to implement as a first
+   pass.  The current Blackfin code also uses an unrolled form of the filter
+   history to avoid 0 length hardware loop issues.  This is wasteful of 
+   memory.
+
+   Ideas for improvement:
+
+   1/ Rewrite filter for dual MAC inner loop.  The issue here is handling
+   history sample offsets that are 16 bit aligned - the dual MAC needs
+   32 bit aligmnent.  There are some good examples in libbfdsp.
+
+   2/ Use the hardware circular buffer facility tohalve memory usage.
+
+   3/ Consider using internal memory.
+
+   Using less memory might also improve speed as cache misses will be
+   reduced. A drop in MIPs and memory approaching 50% should be
+   possible.
+
+   The foreground and background filters currenlty use a total of
+   about 10 MIPs/ch as measured with speedtest.c on a 256 TAP echo
+   can.
+*/
+
+#if defined(USE_MMX)  ||  defined(USE_SSE2)
+#include "mmx.h"
+#endif
+
+/*!
+    16 bit integer FIR descriptor. This defines the working state for a single
+    instance of an FIR filter using 16 bit integer coefficients.
+*/
+typedef struct
+{
+    int taps;
+    int curr_pos;
+    const int16_t *coeffs;
+    int16_t *history;
+} fir16_state_t;
+
+/*!
+    32 bit integer FIR descriptor. This defines the working state for a single
+    instance of an FIR filter using 32 bit integer coefficients, and filtering
+    16 bit integer data.
+*/
+typedef struct
+{
+    int taps;
+    int curr_pos;
+    const int32_t *coeffs;
+    int16_t *history;
+} fir32_state_t;
+
+/*!
+    Floating point FIR descriptor. This defines the working state for a single
+    instance of an FIR filter using floating point coefficients and data.
+*/
+typedef struct
+{
+    int taps;
+    int curr_pos;
+    const float *coeffs;
+    float *history;
+} fir_float_state_t;
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+static __inline__ const int16_t *fir16_create(fir16_state_t *fir,
+                                              const int16_t *coeffs,
+                                              int taps)
+{
+    fir->taps = taps;
+    fir->curr_pos = taps - 1;
+    fir->coeffs = coeffs;
+#if defined(USE_MMX)  ||  defined(USE_SSE2) || defined(__BLACKFIN_ASM__)
+    if ((fir->history = malloc(2*taps*sizeof(int16_t))))
+        memset(fir->history, 0, 2*taps*sizeof(int16_t));
+#else
+    if ((fir->history = (int16_t *) malloc(taps*sizeof(int16_t))))
+        memset(fir->history, 0, taps*sizeof(int16_t));
+#endif
+    return fir->history;
+}
+/*- End of function --------------------------------------------------------*/
+
+static __inline__ void fir16_flush(fir16_state_t *fir)
+{
+#if defined(USE_MMX)  ||  defined(USE_SSE2) || defined(__BLACKFIN_ASM__)
+    memset(fir->history, 0, 2*fir->taps*sizeof(int16_t));
+#else
+    memset(fir->history, 0, fir->taps*sizeof(int16_t));
+#endif
+}
+/*- End of function --------------------------------------------------------*/
+
+static __inline__ void fir16_free(fir16_state_t *fir)
+{
+    free(fir->history);
+}
+/*- End of function --------------------------------------------------------*/
+
+#ifdef __BLACKFIN_ASM__
+static inline int32_t dot_asm(short *x, short *y, int len)
+{
+   int dot;
+
+   len--;
+
+   __asm__ 
+   (
+   "I0 = %1;\n\t"
+   "I1 = %2;\n\t"
+   "A0 = 0;\n\t"
+   "R0.L = W[I0++] || R1.L = W[I1++];\n\t"
+   "LOOP dot%= LC0 = %3;\n\t"
+   "LOOP_BEGIN dot%=;\n\t"
+      "A0 += R0.L * R1.L (IS) || R0.L = W[I0++] || R1.L = W[I1++];\n\t"
+   "LOOP_END dot%=;\n\t"
+   "A0 += R0.L*R1.L (IS);\n\t"
+   "R0 = A0;\n\t"
+   "%0 = R0;\n\t"
+   : "=&d" (dot)
+   : "a" (x), "a" (y), "a" (len)
+   : "I0", "I1", "A1", "A0", "R0", "R1"
+   );
+
+   return dot;
+}
+#endif
+/*- End of function --------------------------------------------------------*/
+
+static __inline__ int16_t fir16(fir16_state_t *fir, int16_t sample)
+{
+    int32_t y;
+#if defined(USE_MMX)
+    int i;
+    mmx_t *mmx_coeffs;
+    mmx_t *mmx_hist;
+
+    fir->history[fir->curr_pos] = sample;
+    fir->history[fir->curr_pos + fir->taps] = sample;
+
+    mmx_coeffs = (mmx_t *) fir->coeffs;
+    mmx_hist = (mmx_t *) &fir->history[fir->curr_pos];
+    i = fir->taps;
+    pxor_r2r(mm4, mm4);
+    /* 8 samples per iteration, so the filter must be a multiple of 8 long. */
+    while (i > 0)
+    {
+        movq_m2r(mmx_coeffs[0], mm0);
+        movq_m2r(mmx_coeffs[1], mm2);
+        movq_m2r(mmx_hist[0], mm1);
+        movq_m2r(mmx_hist[1], mm3);
+        mmx_coeffs += 2;
+        mmx_hist += 2;
+        pmaddwd_r2r(mm1, mm0);
+        pmaddwd_r2r(mm3, mm2);
+        paddd_r2r(mm0, mm4);
+        paddd_r2r(mm2, mm4);
+        i -= 8;
+    }
+    movq_r2r(mm4, mm0);
+    psrlq_i2r(32, mm0);
+    paddd_r2r(mm0, mm4);
+    movd_r2m(mm4, y);
+    emms();
+#elif defined(USE_SSE2)
+    int i;
+    xmm_t *xmm_coeffs;
+    xmm_t *xmm_hist;
+
+    fir->history[fir->curr_pos] = sample;
+    fir->history[fir->curr_pos + fir->taps] = sample;
+
+    xmm_coeffs = (xmm_t *) fir->coeffs;
+    xmm_hist = (xmm_t *) &fir->history[fir->curr_pos];
+    i = fir->taps;
+    pxor_r2r(xmm4, xmm4);
+    /* 16 samples per iteration, so the filter must be a multiple of 16 long. */
+    while (i > 0)
+    {
+        movdqu_m2r(xmm_coeffs[0], xmm0);
+        movdqu_m2r(xmm_coeffs[1], xmm2);
+        movdqu_m2r(xmm_hist[0], xmm1);
+        movdqu_m2r(xmm_hist[1], xmm3);
+        xmm_coeffs += 2;
+        xmm_hist += 2;
+        pmaddwd_r2r(xmm1, xmm0);
+        pmaddwd_r2r(xmm3, xmm2);
+        paddd_r2r(xmm0, xmm4);
+        paddd_r2r(xmm2, xmm4);
+        i -= 16;
+    }
+    movdqa_r2r(xmm4, xmm0);
+    psrldq_i2r(8, xmm0);
+    paddd_r2r(xmm0, xmm4);
+    movdqa_r2r(xmm4, xmm0);
+    psrldq_i2r(4, xmm0);
+    paddd_r2r(xmm0, xmm4);
+    movd_r2m(xmm4, y);
+#elif defined(__BLACKFIN_ASM__)
+    fir->history[fir->curr_pos] = sample;
+    fir->history[fir->curr_pos + fir->taps] = sample;
+    y = dot_asm((int16_t*)fir->coeffs, &fir->history[fir->curr_pos], fir->taps);
+#else
+    int i;
+    int offset1;
+    int offset2;
+
+    fir->history[fir->curr_pos] = sample;
+
+    offset2 = fir->curr_pos;
+    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];
+#endif
+    if (fir->curr_pos <= 0)
+    	fir->curr_pos = fir->taps;
+    fir->curr_pos--;
+    return (int16_t) (y >> 15);
+}
+/*- End of function --------------------------------------------------------*/
+
+static __inline__ const int16_t *fir32_create(fir32_state_t *fir,
+                                              const int32_t *coeffs,
+                                              int taps)
+{
+    fir->taps = taps;
+    fir->curr_pos = taps - 1;
+    fir->coeffs = coeffs;
+    fir->history = (int16_t *) malloc(taps*sizeof(int16_t));
+    if (fir->history)
+    	memset(fir->history, '\0', taps*sizeof(int16_t));
+    return fir->history;
+}
+/*- End of function --------------------------------------------------------*/
+
+static __inline__ void fir32_flush(fir32_state_t *fir)
+{
+    memset(fir->history, 0, fir->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;
+    int32_t y;
+    int offset1;
+    int offset2;
+
+    fir->history[fir->curr_pos] = sample;
+    offset2 = fir->curr_pos;
+    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 (int16_t) (y >> 15);
+}
+/*- End of function --------------------------------------------------------*/
+
+#ifndef __KERNEL__
+static __inline__ const float *fir_float_create(fir_float_state_t *fir,
+                                                const float *coeffs,
+    	    	    	                        int taps)
+{
+    fir->taps = taps;
+    fir->curr_pos = taps - 1;
+    fir->coeffs = coeffs;
+    fir->history = (float *) malloc(taps*sizeof(float));
+    if (fir->history)
+        memset(fir->history, '\0', taps*sizeof(float));
+    return fir->history;
+}
+/*- End of function --------------------------------------------------------*/
+    
+static __inline__ void fir_float_free(fir_float_state_t *fir)
+{
+    free(fir->history);
+}
+/*- End of function --------------------------------------------------------*/
+
+static __inline__ int16_t fir_float(fir_float_state_t *fir, int16_t sample)
+{
+    int i;
+    float y;
+    int offset1;
+    int offset2;
+
+    fir->history[fir->curr_pos] = sample;
+
+    offset2 = fir->curr_pos;
+    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  (int16_t) y;
+}
+/*- End of function --------------------------------------------------------*/
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+/*- End of file ------------------------------------------------------------*/