lib/3rdparty/libsamplerate/src_zoh.c

   1 /*
   2 ** Copyright (C) 2002-2011 Erik de Castro Lopo <erikd@mega-nerd.com>
   3 **
   4 ** This program is free software; you can redistribute it and/or modify
   5 ** it under the terms of the GNU General Public License as published by
   6 ** the Free Software Foundation; either version 2 of the License, or
   7 ** (at your option) any later version.
   8 **
   9 ** This program is distributed in the hope that it will be useful,
  10 ** but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 ** GNU General Public License for more details.
  13 **
  14 ** You should have received a copy of the GNU General Public License
  15 ** along with this program; if not, write to the Free Software
  16 ** Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
  17 */
  18
  19 /*
  20 ** This code is part of Secret Rabbit Code aka libsamplerate. A commercial
  21 ** use license for this code is available, please see:
  22 **              http://www.mega-nerd.com/SRC/procedure.html
  23 */
  24
  25 #include <stdio.h>
  26 #include <stdlib.h>
  27 #include <string.h>
  28
  29 #include "config.h"
  30 #include "float_cast.h"
  31 #include "common.h"
  32
  33 static int zoh_vari_process (SRC_PRIVATE *psrc, SRC_DATA *data) ;
  34 static void zoh_reset (SRC_PRIVATE *psrc) ;
  35
  36 /*========================================================================================
  37 */
  38
  39 #define ZOH_MAGIC_MARKER        MAKE_MAGIC ('s', 'r', 'c', 'z', 'o', 'h')
  40
  41 typedef struct
  42 {       int             zoh_magic_marker ;
  43         int             channels ;
  44         int             reset ;
  45         long    in_count, in_used ;
  46         long    out_count, out_gen ;
  47         float   last_value [1] ;
  48 } ZOH_DATA ;
  49
  50 /*----------------------------------------------------------------------------------------
  51 */
  52
  53 static int
  54 zoh_vari_process (SRC_PRIVATE *psrc, SRC_DATA *data)
  55 {       ZOH_DATA        *priv ;
  56         double          src_ratio, input_index, rem ;
  57         int                     ch ;
  58
  59         if (data->input_frames <= 0)
  60                 return SRC_ERR_NO_ERROR ;
  61
  62         if (psrc->private_data == NULL)
  63                 return SRC_ERR_NO_PRIVATE ;
  64
  65         priv = (ZOH_DATA*) psrc->private_data ;
  66
  67         if (priv->reset)
  68         {       /* If we have just been reset, set the last_value data. */
  69                 for (ch = 0 ; ch < priv->channels ; ch++)
  70                         priv->last_value [ch] = data->data_in [ch] ;
  71                 priv->reset = 0 ;
  72                 } ;
  73
  74         priv->in_count = data->input_frames * priv->channels ;
  75         priv->out_count = data->output_frames * priv->channels ;
  76         priv->in_used = priv->out_gen = 0 ;
  77
  78         src_ratio = psrc->last_ratio ;
  79         input_index = psrc->last_position ;
  80
  81         /* Calculate samples before first sample in input array. */
  82         while (input_index < 1.0 && priv->out_gen < priv->out_count)
  83         {
  84                 if (priv->in_used + priv->channels * input_index >= priv->in_count)
  85                         break ;
  86
  87                 if (priv->out_count > 0 && fabs (psrc->last_ratio - data->src_ratio) > SRC_MIN_RATIO_DIFF)
  88                         src_ratio = psrc->last_ratio + priv->out_gen * (data->src_ratio - psrc->last_ratio) / priv->out_count ;
  89
  90                 for (ch = 0 ; ch < priv->channels ; ch++)
  91                 {       data->data_out [priv->out_gen] = priv->last_value [ch] ;
  92                         priv->out_gen ++ ;
  93                         } ;
  94
  95                 /* Figure out the next index. */
  96                 input_index += 1.0 / src_ratio ;
  97                 } ;
  98
  99         rem = fmod_one (input_index) ;
 100         priv->in_used += priv->channels * lrint (input_index - rem) ;
 101         input_index = rem ;
 102
 103         /* Main processing loop. */
 104         while (priv->out_gen < priv->out_count && priv->in_used + priv->channels * input_index <= priv->in_count)
 105         {
 106                 if (priv->out_count > 0 && fabs (psrc->last_ratio - data->src_ratio) > SRC_MIN_RATIO_DIFF)
 107                         src_ratio = psrc->last_ratio + priv->out_gen * (data->src_ratio - psrc->last_ratio) / priv->out_count ;
 108
 109                 for (ch = 0 ; ch < priv->channels ; ch++)
 110                 {       data->data_out [priv->out_gen] = data->data_in [priv->in_used - priv->channels + ch] ;
 111                         priv->out_gen ++ ;
 112                         } ;
 113
 114                 /* Figure out the next index. */
 115                 input_index += 1.0 / src_ratio ;
 116                 rem = fmod_one (input_index) ;
 117
 118                 priv->in_used += priv->channels * lrint (input_index - rem) ;
 119                 input_index = rem ;
 120                 } ;
 121
 122         if (priv->in_used > priv->in_count)
 123         {       input_index += (priv->in_used - priv->in_count) / priv->channels ;
 124                 priv->in_used = priv->in_count ;
 125                 } ;
 126
 127         psrc->last_position = input_index ;
 128
 129         if (priv->in_used > 0)
 130                 for (ch = 0 ; ch < priv->channels ; ch++)
 131                         priv->last_value [ch] = data->data_in [priv->in_used - priv->channels + ch] ;
 132
 133         /* Save current ratio rather then target ratio. */
 134         psrc->last_ratio = src_ratio ;
 135
 136         data->input_frames_used = priv->in_used / priv->channels ;
 137         data->output_frames_gen = priv->out_gen / priv->channels ;
 138
 139         return SRC_ERR_NO_ERROR ;
 140 } /* zoh_vari_process */
 141
 142 /*------------------------------------------------------------------------------
 143 */
 144
 145 const char*
 146 zoh_get_name (int src_enum)
 147 {
 148         if (src_enum == SRC_ZERO_ORDER_HOLD)
 149                 return "ZOH Interpolator" ;
 150
 151         return NULL ;
 152 } /* zoh_get_name */
 153
 154 const char*
 155 zoh_get_description (int src_enum)
 156 {
 157         if (src_enum == SRC_ZERO_ORDER_HOLD)
 158                 return "Zero order hold interpolator, very fast, poor quality." ;
 159
 160         return NULL ;
 161 } /* zoh_get_descrition */
 162
 163 int
 164 zoh_set_converter (SRC_PRIVATE *psrc, int src_enum)
 165 {       ZOH_DATA *priv = NULL ;
 166
 167         if (src_enum != SRC_ZERO_ORDER_HOLD)
 168                 return SRC_ERR_BAD_CONVERTER ;
 169
 170         if (psrc->private_data != NULL)
 171         {       free (psrc->private_data) ;
 172                 psrc->private_data = NULL ;
 173                 } ;
 174
 175         if (psrc->private_data == NULL)
 176         {       priv = calloc (1, sizeof (*priv) + psrc->channels * sizeof (float)) ;
 177                 if (priv == NULL)
 178                         return SRC_ERR_MALLOC_FAILED ;
 179                 psrc->private_data = priv ;
 180                 } ;
 181
 182         priv->zoh_magic_marker = ZOH_MAGIC_MARKER ;
 183         priv->channels = psrc->channels ;
 184
 185         psrc->const_process = zoh_vari_process ;
 186         psrc->vari_process = zoh_vari_process ;
 187         psrc->reset = zoh_reset ;
 188
 189         zoh_reset (psrc) ;
 190
 191         return SRC_ERR_NO_ERROR ;
 192 } /* zoh_set_converter */
 193
 194 /*===================================================================================
 195 */
 196
 197 static void
 198 zoh_reset (SRC_PRIVATE *psrc)
 199 {       ZOH_DATA *priv ;
 200
 201         priv = (ZOH_DATA*) psrc->private_data ;
 202         if (priv == NULL)
 203                 return ;
 204
 205         priv->channels = psrc->channels ;
 206         priv->reset = 1 ;
 207         memset (priv->last_value, 0, sizeof (priv->last_value [0]) * priv->channels) ;
 208
 209         return ;
 210 } /* zoh_reset */
 211