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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 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.
*/
/*! \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.
*/
/*!
16 bit integer FIR descriptor. This defines the working state for a single
instance of an FIR filter using 16 bit integer coefficients.
*/
struct fir16_state_t {
int taps;
int curr_pos;
const int16_t *coeffs;
int16_t *history;
};
/*!
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.
*/
struct fir32_state_t {
int taps;
int curr_pos;
const int32_t *coeffs;
int16_t *history;
};
/*!
Floating point FIR descriptor. This defines the working state for a single
instance of an FIR filter using floating point coefficients and data.
*/
struct fir_float_state_t {
int taps;
int curr_pos;
const float *coeffs;
float *history;
};
static inline const int16_t *fir16_create(struct fir16_state_t *fir,
const int16_t *coeffs, int taps)
{
fir->taps = taps;
fir->curr_pos = taps - 1;
fir->coeffs = coeffs;
#if defined(USE_SSE2) || defined(__bfin__)
fir->history = kcalloc(2 * taps, sizeof(int16_t), GFP_KERNEL);
#else
fir->history = kcalloc(taps, sizeof(int16_t), GFP_KERNEL);
#endif
return fir->history;
}
static inline void fir16_flush(struct fir16_state_t *fir)
{
#if defined(USE_SSE2) || defined(__bfin__)
memset(fir->history, 0, 2 * fir->taps * sizeof(int16_t));
#else
memset(fir->history, 0, fir->taps * sizeof(int16_t));
#endif
}
static inline void fir16_free(struct fir16_state_t *fir)
{
kfree(fir->history);
}
#ifdef __bfin__
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
static inline int16_t fir16(struct fir16_state_t *fir, int16_t sample)
{
int32_t y;
#if defined(USE_SSE2)
int i;
union xmm_t *xmm_coeffs;
union xmm_t *xmm_hist;
fir->history[fir->curr_pos] = sample;
fir->history[fir->curr_pos + fir->taps] = sample;
xmm_coeffs = (union xmm_t *)fir->coeffs;
xmm_hist = (union 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(__bfin__)
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);
}
static inline const int16_t *fir32_create(struct fir32_state_t *fir,
const int32_t *coeffs, int taps)
{
fir->taps = taps;
fir->curr_pos = taps - 1;
fir->coeffs = coeffs;
fir->history = kcalloc(taps, sizeof(int16_t), GFP_KERNEL);
return fir->history;
}
static inline void fir32_flush(struct fir32_state_t *fir)
{
memset(fir->history, 0, fir->taps * sizeof(int16_t));
}
static inline void fir32_free(struct fir32_state_t *fir)
{
kfree(fir->history);
}
static inline int16_t fir32(struct 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);
}
#endif
/*- End of file ------------------------------------------------------------*/
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