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/*
libdemac - A Monkey's Audio decoder
$Id: filter.c 19556 2008-12-22 08:33:49Z amiconn $
Copyright (C) Dave Chapman 2007
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., 51 Franklin St, Fifth Floor, Boston, MA 02110, USA
*/
#include <string.h>
#include <inttypes.h>
#include "demac.h"
#include "filter.h"
#include "demac_config.h"
#if FILTER_BITS == 32
#if defined(CPU_ARM) && (ARM_ARCH == 4)
#include "vector_math32_armv4.h"
#else
#include "vector_math_generic.h"
#endif
#else /* FILTER_BITS == 16 */
#ifdef CPU_COLDFIRE
#include "vector_math16_cf.h"
#elif defined(CPU_ARM) && (ARM_ARCH >= 6)
#include "vector_math16_armv6.h"
#elif defined(CPU_ARM) && (ARM_ARCH >= 5)
/* Assume all our ARMv5 targets are ARMv5te(j) */
#include "vector_math16_armv5te.h"
#else
#include "vector_math_generic.h"
#endif
#endif /* FILTER_BITS */
struct filter_t {
filter_int* coeffs; /* ORDER entries */
/* We store all the filter delays in a single buffer */
filter_int* history_end;
filter_int* delay;
filter_int* adaptcoeffs;
int avg;
};
/* We name the functions according to the ORDER and FRACBITS
pre-processor symbols and build multiple .o files from this .c file
- this increases code-size but gives the compiler more scope for
optimising the individual functions, as well as replacing a lot of
variables with constants.
*/
#if FRACBITS == 11
#if ORDER == 16
#define INIT_FILTER init_filter_16_11
#define APPLY_FILTER apply_filter_16_11
#elif ORDER == 64
#define INIT_FILTER init_filter_64_11
#define APPLY_FILTER apply_filter_64_11
#endif
#elif FRACBITS == 13
#define INIT_FILTER init_filter_256_13
#define APPLY_FILTER apply_filter_256_13
#elif FRACBITS == 10
#define INIT_FILTER init_filter_32_10
#define APPLY_FILTER apply_filter_32_10
#elif FRACBITS == 15
#define INIT_FILTER init_filter_1280_15
#define APPLY_FILTER apply_filter_1280_15
#endif
/* Some macros to handle the fixed-point stuff */
/* Convert from (32-FRACBITS).FRACBITS fixed-point format to an
integer (rounding to nearest). */
#define FP_HALF (1 << (FRACBITS - 1)) /* 0.5 in fixed-point format. */
#define FP_TO_INT(x) ((x + FP_HALF) >> FRACBITS) /* round(x) */
#if defined(CPU_ARM) && (ARM_ARCH >= 6)
#define SATURATE(x) ({int __res; asm("ssat %0, #16, %1" : "=r"(__res) : "r"(x)); __res; })
#else
#define SATURATE(x) (LIKELY((x) == (int16_t)(x)) ? (x) : ((x) >> 31) ^ 0x7FFF)
#endif
/* Apply the filter with state f to count entries in data[] */
static void ICODE_ATTR_DEMAC do_apply_filter_3980(struct filter_t* f,
int32_t* data, int count)
{
int res;
int absres;
#ifdef PREPARE_SCALARPRODUCT
PREPARE_SCALARPRODUCT
#endif
while(LIKELY(count--))
{
res = FP_TO_INT(scalarproduct(f->coeffs, f->delay - ORDER));
if (LIKELY(*data != 0)) {
if (*data < 0)
vector_add(f->coeffs, f->adaptcoeffs - ORDER);
else
vector_sub(f->coeffs, f->adaptcoeffs - ORDER);
}
res += *data;
*data++ = res;
/* Update the output history */
*f->delay++ = SATURATE(res);
/* Version 3.98 and later files */
/* Update the adaption coefficients */
absres = (res < 0 ? -res : res);
if (UNLIKELY(absres > 3 * f->avg))
*f->adaptcoeffs = ((res >> 25) & 64) - 32;
else if (3 * absres > 4 * f->avg)
*f->adaptcoeffs = ((res >> 26) & 32) - 16;
else if (LIKELY(absres > 0))
*f->adaptcoeffs = ((res >> 27) & 16) - 8;
else
*f->adaptcoeffs = 0;
f->avg += (absres - f->avg) / 16;
f->adaptcoeffs[-1] >>= 1;
f->adaptcoeffs[-2] >>= 1;
f->adaptcoeffs[-8] >>= 1;
f->adaptcoeffs++;
/* Have we filled the history buffer? */
if (UNLIKELY(f->delay == f->history_end)) {
memmove(f->coeffs + ORDER, f->delay - (ORDER*2),
(ORDER*2) * sizeof(filter_int));
f->adaptcoeffs = f->coeffs + ORDER*2;
f->delay = f->coeffs + ORDER*3;
}
}
}
static void ICODE_ATTR_DEMAC do_apply_filter_3970(struct filter_t* f,
int32_t* data, int count)
{
int res;
#ifdef PREPARE_SCALARPRODUCT
PREPARE_SCALARPRODUCT
#endif
while(LIKELY(count--))
{
res = FP_TO_INT(scalarproduct(f->coeffs, f->delay - ORDER));
if (LIKELY(*data != 0)) {
if (*data < 0)
vector_add(f->coeffs, f->adaptcoeffs - ORDER);
else
vector_sub(f->coeffs, f->adaptcoeffs - ORDER);
}
/* Convert res from (32-FRACBITS).FRACBITS fixed-point format to an
integer (rounding to nearest) and add the input value to
it */
res += *data;
*data++ = res;
/* Update the output history */
*f->delay++ = SATURATE(res);
/* Version ??? to < 3.98 files (untested) */
f->adaptcoeffs[0] = (res == 0) ? 0 : ((res >> 28) & 8) - 4;
f->adaptcoeffs[-4] >>= 1;
f->adaptcoeffs[-8] >>= 1;
f->adaptcoeffs++;
/* Have we filled the history buffer? */
if (UNLIKELY(f->delay == f->history_end)) {
memmove(f->coeffs + ORDER, f->delay - (ORDER*2),
(ORDER*2) * sizeof(filter_int));
f->adaptcoeffs = f->coeffs + ORDER*2;
f->delay = f->coeffs + ORDER*3;
}
}
}
static struct filter_t filter0 IBSS_ATTR;
static struct filter_t filter1 IBSS_ATTR;
static void do_init_filter(struct filter_t* f, filter_int* buf)
{
f->coeffs = buf;
f->history_end = buf + ORDER*3 + FILTER_HISTORY_SIZE;
/* Init pointers */
f->adaptcoeffs = f->coeffs + ORDER*2;
f->delay = f->coeffs + ORDER*3;
/* Zero coefficients and history buffer */
memset(f->coeffs, 0, ORDER*3 * sizeof(filter_int));
/* Zero the running average */
f->avg = 0;
}
void INIT_FILTER(filter_int* buf)
{
do_init_filter(&filter0, buf);
do_init_filter(&filter1, buf + ORDER*3 + FILTER_HISTORY_SIZE);
}
void ICODE_ATTR_DEMAC APPLY_FILTER(int fileversion, int32_t* data0,
int32_t* data1, int count)
{
if (fileversion >= 3980) {
do_apply_filter_3980(&filter0, data0, count);
if (data1 != NULL)
do_apply_filter_3980(&filter1, data1, count);
} else {
do_apply_filter_3970(&filter0, data0, count);
if (data1 != NULL)
do_apply_filter_3970(&filter1, data1, count);
}
}
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