sdk/lib/3rdparty/libsamplerate/src_linear.c

   1 /*
   2 ** Copyright (c) 2002-2016, Erik de Castro Lopo <erikd@mega-nerd.com>
   3 ** All rights reserved.
   4 **
   5 ** This code is released under 2-clause BSD license. Please see the
   6 ** file at : https://github.com/erikd/libsamplerate/blob/master/COPYING
   7 */
   8
   9 #include "precomp.h"
  10
  11 static int linear_vari_process (SRC_PRIVATE *psrc, SRC_DATA *data) ;
  12 static void linear_reset (SRC_PRIVATE *psrc) ;
  13
  14 /*========================================================================================
  15 */
  16
  17 #define LINEAR_MAGIC_MARKER     MAKE_MAGIC ('l', 'i', 'n', 'e', 'a', 'r')
  18
  19 #define SRC_DEBUG       0
  20
  21 typedef struct
  22 {       int             linear_magic_marker ;
  23         int             channels ;
  24         int             reset ;
  25         long    in_count, in_used ;
  26         long    out_count, out_gen ;
  27         float   last_value [1] ;
  28 } LINEAR_DATA ;
  29
  30 /*----------------------------------------------------------------------------------------
  31 */
  32
  33 static int
  34 linear_vari_process (SRC_PRIVATE *psrc, SRC_DATA *data)
  35 {       LINEAR_DATA *priv ;
  36         double          src_ratio, input_index, rem ;
  37         int                     ch ;
  38
  39         if (data->input_frames <= 0)
  40                 return SRC_ERR_NO_ERROR ;
  41
  42         if (psrc->private_data == NULL)
  43                 return SRC_ERR_NO_PRIVATE ;
  44
  45         priv = (LINEAR_DATA*) psrc->private_data ;
  46
  47         if (priv->reset)
  48         {       /* If we have just been reset, set the last_value data. */
  49                 for (ch = 0 ; ch < priv->channels ; ch++)
  50                         priv->last_value [ch] = data->data_in [ch] ;
  51                 priv->reset = 0 ;
  52                 } ;
  53
  54         priv->in_count = data->input_frames * priv->channels ;
  55         priv->out_count = data->output_frames * priv->channels ;
  56         priv->in_used = priv->out_gen = 0 ;
  57
  58         src_ratio = psrc->last_ratio ;
  59
  60         if (is_bad_src_ratio (src_ratio))
  61                 return SRC_ERR_BAD_INTERNAL_STATE ;
  62
  63         input_index = psrc->last_position ;
  64
  65         /* Calculate samples before first sample in input array. */
  66         while (input_index < 1.0 && priv->out_gen < priv->out_count)
  67         {
  68                 if (priv->in_used + priv->channels * (1.0 + input_index) >= priv->in_count)
  69                         break ;
  70
  71                 if (priv->out_count > 0 && fabs (psrc->last_ratio - data->src_ratio) > SRC_MIN_RATIO_DIFF)
  72                         src_ratio = psrc->last_ratio + priv->out_gen * (data->src_ratio - psrc->last_ratio) / priv->out_count ;
  73
  74                 for (ch = 0 ; ch < priv->channels ; ch++)
  75                 {       data->data_out [priv->out_gen] = (float) (priv->last_value [ch] + input_index *
  76                                                                                 (data->data_in [ch] - priv->last_value [ch])) ;
  77                         priv->out_gen ++ ;
  78                         } ;
  79
  80                 /* Figure out the next index. */
  81                 input_index += 1.0 / src_ratio ;
  82                 } ;
  83
  84         rem = fmod_one (input_index) ;
  85         priv->in_used += priv->channels * lrint (input_index - rem) ;
  86         input_index = rem ;
  87
  88         /* Main processing loop. */
  89         while (priv->out_gen < priv->out_count && priv->in_used + priv->channels * input_index < priv->in_count)
  90         {
  91                 if (priv->out_count > 0 && fabs (psrc->last_ratio - data->src_ratio) > SRC_MIN_RATIO_DIFF)
  92                         src_ratio = psrc->last_ratio + priv->out_gen * (data->src_ratio - psrc->last_ratio) / priv->out_count ;
  93
  94                 if (SRC_DEBUG && priv->in_used < priv->channels && input_index < 1.0)
  95                 {       printf ("Whoops!!!!   in_used : %ld     channels : %d     input_index : %f\n", priv->in_used, priv->channels, input_index) ;
  96                         exit (1) ;
  97                         } ;
  98
  99                 for (ch = 0 ; ch < priv->channels ; ch++)
 100                 {       data->data_out [priv->out_gen] = (float) (data->data_in [priv->in_used - priv->channels + ch] + input_index *
 101                                                 (data->data_in [priv->in_used + ch] - data->data_in [priv->in_used - priv->channels + ch])) ;
 102                         priv->out_gen ++ ;
 103                         } ;
 104
 105                 /* Figure out the next index. */
 106                 input_index += 1.0 / src_ratio ;
 107                 rem = fmod_one (input_index) ;
 108
 109                 priv->in_used += priv->channels * lrint (input_index - rem) ;
 110                 input_index = rem ;
 111                 } ;
 112
 113         if (priv->in_used > priv->in_count)
 114         {       input_index += (priv->in_used - priv->in_count) / priv->channels ;
 115                 priv->in_used = priv->in_count ;
 116                 } ;
 117
 118         psrc->last_position = input_index ;
 119
 120         if (priv->in_used > 0)
 121                 for (ch = 0 ; ch < priv->channels ; ch++)
 122                         priv->last_value [ch] = data->data_in [priv->in_used - priv->channels + ch] ;
 123
 124         /* Save current ratio rather then target ratio. */
 125         psrc->last_ratio = src_ratio ;
 126
 127         data->input_frames_used = priv->in_used / priv->channels ;
 128         data->output_frames_gen = priv->out_gen / priv->channels ;
 129
 130         return SRC_ERR_NO_ERROR ;
 131 } /* linear_vari_process */
 132
 133 /*------------------------------------------------------------------------------
 134 */
 135
 136 const char*
 137 linear_get_name (int src_enum)
 138 {
 139         if (src_enum == SRC_LINEAR)
 140                 return "Linear Interpolator" ;
 141
 142         return NULL ;
 143 } /* linear_get_name */
 144
 145 const char*
 146 linear_get_description (int src_enum)
 147 {
 148         if (src_enum == SRC_LINEAR)
 149                 return "Linear interpolator, very fast, poor quality." ;
 150
 151         return NULL ;
 152 } /* linear_get_descrition */
 153
 154 int
 155 linear_set_converter (SRC_PRIVATE *psrc, int src_enum)
 156 {       LINEAR_DATA *priv = NULL ;
 157
 158         if (src_enum != SRC_LINEAR)
 159                 return SRC_ERR_BAD_CONVERTER ;
 160
 161         if (psrc->private_data != NULL)
 162         {       free (psrc->private_data) ;
 163                 psrc->private_data = NULL ;
 164                 } ;
 165
 166         if (psrc->private_data == NULL)
 167         {       priv = calloc (1, sizeof (*priv) + psrc->channels * sizeof (float)) ;
 168                 psrc->private_data = priv ;
 169                 } ;
 170
 171         if (priv == NULL)
 172                 return SRC_ERR_MALLOC_FAILED ;
 173
 174         priv->linear_magic_marker = LINEAR_MAGIC_MARKER ;
 175         priv->channels = psrc->channels ;
 176
 177         psrc->const_process = linear_vari_process ;
 178         psrc->vari_process = linear_vari_process ;
 179         psrc->reset = linear_reset ;
 180
 181         linear_reset (psrc) ;
 182
 183         return SRC_ERR_NO_ERROR ;
 184 } /* linear_set_converter */
 185
 186 /*===================================================================================
 187 */
 188
 189 static void
 190 linear_reset (SRC_PRIVATE *psrc)
 191 {       LINEAR_DATA *priv = NULL ;
 192
 193         priv = (LINEAR_DATA*) psrc->private_data ;
 194         if (priv == NULL)
 195                 return ;
 196
 197         priv->channels = psrc->channels ;
 198         priv->reset = 1 ;
 199         memset (priv->last_value, 0, sizeof (priv->last_value [0]) * priv->channels) ;
 200
 201         return ;
 202 } /* linear_reset */
 203