/*** FAAD2 - Freeware Advanced Audio (AAC) Decoder including SBR decoding** Copyright (C) 2003-2005 M. Bakker, Nero AG, http://www.nero.com**** 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.**** Any non-GPL usage of this software or parts of this software is strictly** forbidden.**** The "appropriate copyright message" mentioned in section 2c of the GPLv2** must read: "Code from FAAD2 is copyright (c) Nero AG, www.nero.com"**** Commercial non-GPL licensing of this software is possible.** For more info contact Nero AG through Mpeg4AAClicense@nero.com.**** $Id: lt_predict.c,v 1.27 2007/11/01 12:33:31 menno Exp $**/  #include "common.h"#include "structs.h" #ifdef LTP_DEC #include "syntax.h"#include "lt_predict.h"#include "filtbank.h"#include "tns.h"  /* static function declarations */static int16_t real_to_int16(real_t sig_in);  /* check if the object type is an object type that can have LTP */uint8_t is_ltp_ot(uint8_t object_type){#ifdef LTP_DEC    if ((object_type == LTP)#ifdef ERROR_RESILIENCE        || (object_type == ER_LTP)#endif#ifdef LD_DEC        || (object_type == LD)#endif        )    {        return 1;    }#endif     return 0;} ALIGN static const real_t codebook[8] ={    REAL_CONST(0.570829),    REAL_CONST(0.696616),    REAL_CONST(0.813004),    REAL_CONST(0.911304),    REAL_CONST(0.984900),    REAL_CONST(1.067894),    REAL_CONST(1.194601),    REAL_CONST(1.369533)}; void lt_prediction(ic_stream *ics, ltp_info *ltp, real_t *spec,                   int16_t *lt_pred_stat, fb_info *fb, uint8_t win_shape,                   uint8_t win_shape_prev, uint8_t sr_index,                   uint8_t object_type, uint16_t frame_len){    uint8_t sfb;    uint16_t bin, i, num_samples;    ALIGN real_t x_est[2048];    ALIGN real_t X_est[2048];     if (ics->window_sequence != EIGHT_SHORT_SEQUENCE)    {        if (ltp->data_present)        {            num_samples = frame_len << 1;             for(i = 0; i < num_samples; i++)            {                /* The extra lookback M (N/2 for LD, 0 for LTP) is handled                   in the buffer updating */ #if 0                x_est[i] = MUL_R_C(lt_pred_stat[num_samples + i - ltp->lag],                    codebook[ltp->coef]);#else                /* lt_pred_stat is a 16 bit int, multiplied with the fixed point real                   this gives a real for x_est                */                x_est[i] = (real_t)lt_pred_stat[num_samples + i - ltp->lag] * codebook[ltp->coef];#endif            }             filter_bank_ltp(fb, ics->window_sequence, win_shape, win_shape_prev,                x_est, X_est, object_type, frame_len);             tns_encode_frame(ics, &(ics->tns), sr_index, object_type, X_est,                frame_len);             for (sfb = 0; sfb < ltp->last_band; sfb++)            {                if (ltp->long_used[sfb])                {                    uint16_t low  = ics->swb_offset[sfb];                    uint16_t high = min(ics->swb_offset[sfb+1], ics->swb_offset_max);                     for (bin = low; bin < high; bin++)                    {                        spec[bin] += X_est[bin];                    }                }            }        }    }} #ifdef FIXED_POINTstatic INLINE int16_t real_to_int16(real_t sig_in){    if (sig_in >= 0)    {        sig_in += (1 << (REAL_BITS-1));        if (sig_in >= REAL_CONST(32768))            return 32767;    } else {        sig_in += -(1 << (REAL_BITS-1));        if (sig_in <= REAL_CONST(-32768))            return -32768;    }     return (int16_t)(sig_in >> REAL_BITS);}#elsestatic INLINE int16_t real_to_int16(real_t sig_in){    if (sig_in >= 0)    {#ifndef HAS_LRINTF        sig_in += 0.5f;#endif        if (sig_in >= 32768.0f)            return 32767;    } else {#ifndef HAS_LRINTF        sig_in += -0.5f;#endif        if (sig_in <= -32768.0f)            return -32768;    }     return (int16_t)lrintf(sig_in);}#endif void lt_update_state(int16_t *lt_pred_stat, real_t *time, real_t *overlap,                     uint16_t frame_len, uint8_t object_type){    uint16_t i;     /*     * The reference point for index i and the content of the buffer     * lt_pred_stat are arranged so that lt_pred_stat(0 ... N/2 - 1) contains the     * last aliased half window from the IMDCT, and lt_pred_stat(N/2 ... N-1)     * is always all zeros. The rest of lt_pred_stat (i<0) contains the previous     * fully reconstructed time domain samples, i.e., output of the decoder.     *     * These values are shifted up by N*2 to avoid (i<0)     *     * For the LD object type an extra 512 samples lookback is accomodated here.     */#ifdef LD_DEC    if (object_type == LD)    {        for (i = 0; i < frame_len; i++)        {            lt_pred_stat[i]  /* extra 512 */  = lt_pred_stat[i + frame_len];            lt_pred_stat[frame_len + i]       = lt_pred_stat[i + (frame_len * 2)];            lt_pred_stat[(frame_len * 2) + i] = real_to_int16(time[i]);            lt_pred_stat[(frame_len * 3) + i] = real_to_int16(overlap[i]);        }    } else {#endif        for (i = 0; i < frame_len; i++)        {            lt_pred_stat[i]                   = lt_pred_stat[i + frame_len];            lt_pred_stat[frame_len + i]       = real_to_int16(time[i]);            lt_pred_stat[(frame_len * 2) + i] = real_to_int16(overlap[i]);#if 0 /* set to zero once upon initialisation */            lt_pred_stat[(frame_len * 3) + i] = 0;#endif        }#ifdef LD_DEC    }#endif} #endif