GCC Code Coverage Report
Directory: ../../../ffmpeg/ Exec Total Coverage
File: src/libavcodec/lpc.h Lines: 41 42 97.6 %
Date: 2019-11-22 03:34:36 Branches: 26 30 86.7 %

Line Branch Exec Source
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/*
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 * LPC utility code
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 * Copyright (c) 2006  Justin Ruggles <justin.ruggles@gmail.com>
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 *
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 * This file is part of FFmpeg.
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 *
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 * FFmpeg is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * FFmpeg is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with FFmpeg; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
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#ifndef AVCODEC_LPC_H
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#define AVCODEC_LPC_H
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#include <stdint.h>
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#include "libavutil/avassert.h"
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#include "libavutil/lls.h"
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#include "aac_defines.h"
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#define ORDER_METHOD_EST     0
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#define ORDER_METHOD_2LEVEL  1
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#define ORDER_METHOD_4LEVEL  2
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#define ORDER_METHOD_8LEVEL  3
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#define ORDER_METHOD_SEARCH  4
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#define ORDER_METHOD_LOG     5
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#define MIN_LPC_ORDER        1
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#define MAX_LPC_ORDER       32
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/**
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 * LPC analysis type
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 */
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enum FFLPCType {
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    FF_LPC_TYPE_DEFAULT     = -1, ///< use the codec default LPC type
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    FF_LPC_TYPE_NONE        =  0, ///< do not use LPC prediction or use all zero coefficients
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    FF_LPC_TYPE_FIXED       =  1, ///< fixed LPC coefficients
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    FF_LPC_TYPE_LEVINSON    =  2, ///< Levinson-Durbin recursion
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    FF_LPC_TYPE_CHOLESKY    =  3, ///< Cholesky factorization
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    FF_LPC_TYPE_NB              , ///< Not part of ABI
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};
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typedef struct LPCContext {
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    int blocksize;
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    int max_order;
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    enum FFLPCType lpc_type;
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    double *windowed_buffer;
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    double *windowed_samples;
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    /**
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     * Apply a Welch window to an array of input samples.
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     * The output samples have the same scale as the input, but are in double
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     * sample format.
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     * @param data    input samples
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     * @param len     number of input samples
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     * @param w_data  output samples
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     */
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    void (*lpc_apply_welch_window)(const int32_t *data, int len,
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                                   double *w_data);
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    /**
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     * Perform autocorrelation on input samples with delay of 0 to lag.
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     * @param data  input samples.
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     *              constraints: no alignment needed, but must have at
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     *              least lag*sizeof(double) valid bytes preceding it, and
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     *              size must be at least (len+1)*sizeof(double) if data is
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     *              16-byte aligned or (len+2)*sizeof(double) if data is
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     *              unaligned.
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     * @param len   number of input samples to process
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     * @param lag   maximum delay to calculate
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     * @param autoc output autocorrelation coefficients.
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     *              constraints: array size must be at least lag+1.
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     */
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    void (*lpc_compute_autocorr)(const double *data, int len, int lag,
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                                 double *autoc);
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    // TODO: these should be allocated to reduce ABI compatibility issues
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    LLSModel lls_models[2];
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} LPCContext;
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/**
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 * Calculate LPC coefficients for multiple orders
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 */
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int ff_lpc_calc_coefs(LPCContext *s,
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                      const int32_t *samples, int blocksize, int min_order,
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                      int max_order, int precision,
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                      int32_t coefs[][MAX_LPC_ORDER], int *shift,
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                      enum FFLPCType lpc_type, int lpc_passes,
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                      int omethod, int min_shift, int max_shift, int zero_shift);
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int ff_lpc_calc_ref_coefs(LPCContext *s,
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                          const int32_t *samples, int order, double *ref);
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double ff_lpc_calc_ref_coefs_f(LPCContext *s, const float *samples, int len,
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                               int order, double *ref);
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/**
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 * Initialize LPCContext.
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 */
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int ff_lpc_init(LPCContext *s, int blocksize, int max_order,
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                enum FFLPCType lpc_type);
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void ff_lpc_init_x86(LPCContext *s);
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/**
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 * Uninitialize LPCContext.
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 */
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void ff_lpc_end(LPCContext *s);
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#if USE_FIXED
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typedef int LPC_TYPE;
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typedef unsigned LPC_TYPE_U;
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#else
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#ifdef LPC_USE_DOUBLE
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typedef double LPC_TYPE;
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typedef double LPC_TYPE_U;
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#else
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typedef float LPC_TYPE;
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typedef float LPC_TYPE_U;
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#endif
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#endif // USE_FIXED
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/**
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 * Schur recursion.
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 * Produces reflection coefficients from autocorrelation data.
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 */
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static inline void compute_ref_coefs(const LPC_TYPE *autoc, int max_order,
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                                     LPC_TYPE *ref, LPC_TYPE *error)
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{
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    int i, j;
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    LPC_TYPE err;
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    LPC_TYPE gen0[MAX_LPC_ORDER], gen1[MAX_LPC_ORDER];
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    for (i = 0; i < max_order; i++)
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        gen0[i] = gen1[i] = autoc[i + 1];
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    err    = autoc[0];
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    ref[0] = -gen1[0] / err;
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    err   +=  gen1[0] * ref[0];
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    if (error)
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        error[0] = err;
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    for (i = 1; i < max_order; i++) {
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        for (j = 0; j < max_order - i; j++) {
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            gen1[j] = gen1[j + 1] + ref[i - 1] * gen0[j];
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            gen0[j] = gen1[j + 1] * ref[i - 1] + gen0[j];
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        }
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        ref[i] = -gen1[0] / err;
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        err   +=  gen1[0] * ref[i];
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        if (error)
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            error[i] = err;
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    }
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}
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/**
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 * Levinson-Durbin recursion.
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 * Produce LPC coefficients from autocorrelation data.
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 */
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static inline int AAC_RENAME(compute_lpc_coefs)(const LPC_TYPE *autoc, int max_order,
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                                    LPC_TYPE *lpc, int lpc_stride, int fail,
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                                    int normalize)
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{
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    int i, j;
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    LPC_TYPE err = 0;
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    LPC_TYPE *lpc_last = lpc;
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    av_assert2(normalize || !fail);
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    if (normalize)
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        err = *autoc++;
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    if (fail && (autoc[max_order - 1] == 0 || err <= 0))
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        return -1;
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    for(i=0; i<max_order; i++) {
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        LPC_TYPE r = AAC_SRA_R(-autoc[i], 5);
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        if (normalize) {
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            for(j=0; j<i; j++)
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                r -= lpc_last[j] * autoc[i-j-1];
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            r /= err;
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            err *= FIXR(1.0) - (r * r);
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        }
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        lpc[i] = r;
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        for(j=0; j < (i+1)>>1; j++) {
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            LPC_TYPE f = lpc_last[    j];
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            LPC_TYPE b = lpc_last[i-1-j];
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            lpc[    j] = f + (LPC_TYPE_U)AAC_MUL26(r, b);
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            lpc[i-1-j] = b + (LPC_TYPE_U)AAC_MUL26(r, f);
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        }
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        if (fail && err < 0)
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            return -1;
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        lpc_last = lpc;
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        lpc += lpc_stride;
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    }
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    return 0;
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}
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#endif /* AVCODEC_LPC_H */