129 lines
4.7 KiB
C
129 lines
4.7 KiB
C
/* L3SubBand */
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#include "l3subband.h"
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#include "tables.h"
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#include "types.h"
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/*
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* shine_subband_initialise:
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* ----------------------
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* Calculates the analysis filterbank coefficients and rounds to the
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* 9th decimal place accuracy of the filterbank tables in the ISO
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* document. The coefficients are stored in #filter#
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*/
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void shine_subband_initialise(shine_global_config *config) {
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int i, j;
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double filter;
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for (i = MAX_CHANNELS; i--;) {
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config->subband.off[i] = 0;
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memset(config->subband.x[i], 0, sizeof(config->subband.x[i]));
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}
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for (i = SBLIMIT; i--;)
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for (j = 64; j--;) {
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if ((filter = 1e9 * cos((double)((2 * i + 1) * (16 - j) * PI64))) >= 0)
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modf(filter + 0.5, &filter);
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else
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modf(filter - 0.5, &filter);
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/* scale and convert to fixed point before storing */
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config->subband.fl[i][j] = (int32_t)(filter * (0x7fffffff * 1e-9));
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}
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}
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/*
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* shine_window_filter_subband:
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* -------------------------
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* Overlapping window on PCM samples
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* 32 16-bit pcm samples are scaled to fractional 2's complement and
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* concatenated to the end of the window buffer #x#. The updated window
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* buffer #x# is then windowed by the analysis window #shine_enwindow# to
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* produce the windowed sample #z# Calculates the analysis filter bank
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* coefficients The windowed samples #z# is filtered by the digital filter
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* matrix #filter# to produce the subband samples #s#. This done by first
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* selectively picking out values from the windowed samples, and then
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* multiplying them by the filter matrix, producing 32 subband samples.
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*/
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void shine_window_filter_subband(int16_t **buffer, int32_t s[SBLIMIT], int ch,
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shine_global_config *config, int stride) {
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int32_t y[64];
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int i, j;
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int16_t *ptr = *buffer;
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/* replace 32 oldest samples with 32 new samples */
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for (i = 32; i--;) {
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config->subband.x[ch][i + config->subband.off[ch]] = ((int32_t)*ptr) << 16;
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ptr += stride;
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}
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*buffer = ptr;
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for (i = 64; i--;) {
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int32_t s_value;
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#ifdef __BORLANDC__
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uint32_t s_value_lo;
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#else
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uint32_t s_value_lo __attribute__((unused));
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#endif
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mul0(s_value, s_value_lo,
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config->subband
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.x[ch][(config->subband.off[ch] + i + (0 << 6)) & (HAN_SIZE - 1)],
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shine_enwindow[i + (0 << 6)]);
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muladd(s_value, s_value_lo,
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config->subband.x[ch][(config->subband.off[ch] + i + (1 << 6)) &
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(HAN_SIZE - 1)],
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shine_enwindow[i + (1 << 6)]);
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muladd(s_value, s_value_lo,
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config->subband.x[ch][(config->subband.off[ch] + i + (2 << 6)) &
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(HAN_SIZE - 1)],
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shine_enwindow[i + (2 << 6)]);
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muladd(s_value, s_value_lo,
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config->subband.x[ch][(config->subband.off[ch] + i + (3 << 6)) &
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(HAN_SIZE - 1)],
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shine_enwindow[i + (3 << 6)]);
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muladd(s_value, s_value_lo,
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config->subband.x[ch][(config->subband.off[ch] + i + (4 << 6)) &
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(HAN_SIZE - 1)],
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shine_enwindow[i + (4 << 6)]);
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muladd(s_value, s_value_lo,
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config->subband.x[ch][(config->subband.off[ch] + i + (5 << 6)) &
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(HAN_SIZE - 1)],
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shine_enwindow[i + (5 << 6)]);
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muladd(s_value, s_value_lo,
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config->subband.x[ch][(config->subband.off[ch] + i + (6 << 6)) &
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(HAN_SIZE - 1)],
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shine_enwindow[i + (6 << 6)]);
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muladd(s_value, s_value_lo,
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config->subband.x[ch][(config->subband.off[ch] + i + (7 << 6)) &
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(HAN_SIZE - 1)],
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shine_enwindow[i + (7 << 6)]);
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mulz(s_value, s_value_lo);
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y[i] = s_value;
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}
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config->subband.off[ch] = (config->subband.off[ch] + 480) &
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(HAN_SIZE - 1); /* offset is modulo (HAN_SIZE)*/
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for (i = SBLIMIT; i--;) {
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int32_t s_value;
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#ifdef __BORLANDC__
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uint32_t s_value_lo;
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#else
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uint32_t s_value_lo __attribute__((unused));
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#endif
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mul0(s_value, s_value_lo, config->subband.fl[i][63], y[63]);
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for (j = 63; j; j -= 7) {
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muladd(s_value, s_value_lo, config->subband.fl[i][j - 1], y[j - 1]);
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muladd(s_value, s_value_lo, config->subband.fl[i][j - 2], y[j - 2]);
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muladd(s_value, s_value_lo, config->subband.fl[i][j - 3], y[j - 3]);
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muladd(s_value, s_value_lo, config->subband.fl[i][j - 4], y[j - 4]);
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muladd(s_value, s_value_lo, config->subband.fl[i][j - 5], y[j - 5]);
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muladd(s_value, s_value_lo, config->subband.fl[i][j - 6], y[j - 6]);
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muladd(s_value, s_value_lo, config->subband.fl[i][j - 7], y[j - 7]);
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}
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mulz(s_value, s_value_lo);
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s[i] = s_value;
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}
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}
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