sdk/lib/3rdparty/libsamplerate/src_zoh.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 zoh_vari_process (SRC_PRIVATE *psrc, SRC_DATA *data) ;
  12 static void zoh_reset (SRC_PRIVATE *psrc) ;
  13
  14 /*========================================================================================
  15 */
  16
  17 #define ZOH_MAGIC_MARKER        MAKE_MAGIC ('s', 'r', 'c', 'z', 'o', 'h')
  18
  19 typedef struct
  20 {       int             zoh_magic_marker ;
  21         int             channels ;
  22         int             reset ;
  23         long    in_count, in_used ;
  24         long    out_count, out_gen ;
  25         float   last_value [1] ;
  26 } ZOH_DATA ;
  27
  28 /*----------------------------------------------------------------------------------------
  29 */
  30
  31 static int
  32 zoh_vari_process (SRC_PRIVATE *psrc, SRC_DATA *data)
  33 {       ZOH_DATA        *priv ;
  34         double          src_ratio, input_index, rem ;
  35         int                     ch ;
  36
  37         if (data->input_frames <= 0)
  38                 return SRC_ERR_NO_ERROR ;
  39
  40         if (psrc->private_data == NULL)
  41                 return SRC_ERR_NO_PRIVATE ;
  42
  43         priv = (ZOH_DATA*) psrc->private_data ;
  44
  45         if (priv->reset)
  46         {       /* If we have just been reset, set the last_value data. */
  47                 for (ch = 0 ; ch < priv->channels ; ch++)
  48                         priv->last_value [ch] = data->data_in [ch] ;
  49                 priv->reset = 0 ;
  50                 } ;
  51
  52         priv->in_count = data->input_frames * priv->channels ;
  53         priv->out_count = data->output_frames * priv->channels ;
  54         priv->in_used = priv->out_gen = 0 ;
  55
  56         src_ratio = psrc->last_ratio ;
  57
  58         if (is_bad_src_ratio (src_ratio))
  59                 return SRC_ERR_BAD_INTERNAL_STATE ;
  60
  61         input_index = psrc->last_position ;
  62
  63         /* Calculate samples before first sample in input array. */
  64         while (input_index < 1.0 && priv->out_gen < priv->out_count)
  65         {
  66                 if (priv->in_used + priv->channels * input_index >= priv->in_count)
  67                         break ;
  68
  69                 if (priv->out_count > 0 && fabs (psrc->last_ratio - data->src_ratio) > SRC_MIN_RATIO_DIFF)
  70                         src_ratio = psrc->last_ratio + priv->out_gen * (data->src_ratio - psrc->last_ratio) / priv->out_count ;
  71
  72                 for (ch = 0 ; ch < priv->channels ; ch++)
  73                 {       data->data_out [priv->out_gen] = priv->last_value [ch] ;
  74                         priv->out_gen ++ ;
  75                         } ;
  76
  77                 /* Figure out the next index. */
  78                 input_index += 1.0 / src_ratio ;
  79                 } ;
  80
  81         rem = fmod_one (input_index) ;
  82         priv->in_used += priv->channels * lrint (input_index - rem) ;
  83         input_index = rem ;
  84
  85         /* Main processing loop. */
  86         while (priv->out_gen < priv->out_count && priv->in_used + priv->channels * input_index <= priv->in_count)
  87         {
  88                 if (priv->out_count > 0 && fabs (psrc->last_ratio - data->src_ratio) > SRC_MIN_RATIO_DIFF)
  89                         src_ratio = psrc->last_ratio + priv->out_gen * (data->src_ratio - psrc->last_ratio) / priv->out_count ;
  90
  91                 for (ch = 0 ; ch < priv->channels ; ch++)
  92                 {       data->data_out [priv->out_gen] = data->data_in [priv->in_used - priv->channels + ch] ;
  93                         priv->out_gen ++ ;
  94                         } ;
  95
  96                 /* Figure out the next index. */
  97                 input_index += 1.0 / src_ratio ;
  98                 rem = fmod_one (input_index) ;
  99
 100                 priv->in_used += priv->channels * lrint (input_index - rem) ;
 101                 input_index = rem ;
 102                 } ;
 103
 104         if (priv->in_used > priv->in_count)
 105         {       input_index += (priv->in_used - priv->in_count) / priv->channels ;
 106                 priv->in_used = priv->in_count ;
 107                 } ;
 108
 109         psrc->last_position = input_index ;
 110
 111         if (priv->in_used > 0)
 112                 for (ch = 0 ; ch < priv->channels ; ch++)
 113                         priv->last_value [ch] = data->data_in [priv->in_used - priv->channels + ch] ;
 114
 115         /* Save current ratio rather then target ratio. */
 116         psrc->last_ratio = src_ratio ;
 117
 118         data->input_frames_used = priv->in_used / priv->channels ;
 119         data->output_frames_gen = priv->out_gen / priv->channels ;
 120
 121         return SRC_ERR_NO_ERROR ;
 122 } /* zoh_vari_process */
 123
 124 /*------------------------------------------------------------------------------
 125 */
 126
 127 const char*
 128 zoh_get_name (int src_enum)
 129 {
 130         if (src_enum == SRC_ZERO_ORDER_HOLD)
 131                 return "ZOH Interpolator" ;
 132
 133         return NULL ;
 134 } /* zoh_get_name */
 135
 136 const char*
 137 zoh_get_description (int src_enum)
 138 {
 139         if (src_enum == SRC_ZERO_ORDER_HOLD)
 140                 return "Zero order hold interpolator, very fast, poor quality." ;
 141
 142         return NULL ;
 143 } /* zoh_get_descrition */
 144
 145 int
 146 zoh_set_converter (SRC_PRIVATE *psrc, int src_enum)
 147 {       ZOH_DATA *priv = NULL ;
 148
 149         if (src_enum != SRC_ZERO_ORDER_HOLD)
 150                 return SRC_ERR_BAD_CONVERTER ;
 151
 152         if (psrc->private_data != NULL)
 153         {       free (psrc->private_data) ;
 154                 psrc->private_data = NULL ;
 155                 } ;
 156
 157         if (psrc->private_data == NULL)
 158         {       priv = calloc (1, sizeof (*priv) + psrc->channels * sizeof (float)) ;
 159                 psrc->private_data = priv ;
 160                 } ;
 161
 162         if (priv == NULL)
 163                 return SRC_ERR_MALLOC_FAILED ;
 164
 165         priv->zoh_magic_marker = ZOH_MAGIC_MARKER ;
 166         priv->channels = psrc->channels ;
 167
 168         psrc->const_process = zoh_vari_process ;
 169         psrc->vari_process = zoh_vari_process ;
 170         psrc->reset = zoh_reset ;
 171
 172         zoh_reset (psrc) ;
 173
 174         return SRC_ERR_NO_ERROR ;
 175 } /* zoh_set_converter */
 176
 177 /*===================================================================================
 178 */
 179
 180 static void
 181 zoh_reset (SRC_PRIVATE *psrc)
 182 {       ZOH_DATA *priv ;
 183
 184         priv = (ZOH_DATA*) psrc->private_data ;
 185         if (priv == NULL)
 186                 return ;
 187
 188         priv->channels = psrc->channels ;
 189         priv->reset = 1 ;
 190         memset (priv->last_value, 0, sizeof (priv->last_value [0]) * priv->channels) ;
 191
 192         return ;
 193 } /* zoh_reset */
 194