X-Git-Url: http://git.ieval.ro/?a=blobdiff_plain;f=libsamplerate%2Fsrc%2Fsrc_zoh.c;fp=libsamplerate%2Fsrc%2Fsrc_zoh.c;h=93ffc236b677cb8307b32b3cc4a8eee3e4edaaf6;hb=8529da432e52c7903e8ef3488e60725a099e6e63;hp=0000000000000000000000000000000000000000;hpb=27013d8f68878b8ed2d3f747e26f562d08d7d678;p=audio-libsamplerate.git diff --git a/libsamplerate/src/src_zoh.c b/libsamplerate/src/src_zoh.c new file mode 100644 index 0000000..93ffc23 --- /dev/null +++ b/libsamplerate/src/src_zoh.c @@ -0,0 +1,200 @@ +/* +** Copyright (c) 2002-2016, Erik de Castro Lopo +** All rights reserved. +** +** This code is released under 2-clause BSD license. Please see the +** file at : https://github.com/erikd/libsamplerate/blob/master/COPYING +*/ + +#include +#include +#include + +#include "config.h" +#include "float_cast.h" +#include "common.h" + +static int zoh_vari_process (SRC_PRIVATE *psrc, SRC_DATA *data) ; +static void zoh_reset (SRC_PRIVATE *psrc) ; + +/*======================================================================================== +*/ + +#define ZOH_MAGIC_MARKER MAKE_MAGIC ('s', 'r', 'c', 'z', 'o', 'h') + +typedef struct +{ int zoh_magic_marker ; + int channels ; + int reset ; + long in_count, in_used ; + long out_count, out_gen ; + float last_value [1] ; +} ZOH_DATA ; + +/*---------------------------------------------------------------------------------------- +*/ + +static int +zoh_vari_process (SRC_PRIVATE *psrc, SRC_DATA *data) +{ ZOH_DATA *priv ; + double src_ratio, input_index, rem ; + int ch ; + + if (data->input_frames <= 0) + return SRC_ERR_NO_ERROR ; + + if (psrc->private_data == NULL) + return SRC_ERR_NO_PRIVATE ; + + priv = (ZOH_DATA*) psrc->private_data ; + + if (priv->reset) + { /* If we have just been reset, set the last_value data. */ + for (ch = 0 ; ch < priv->channels ; ch++) + priv->last_value [ch] = data->data_in [ch] ; + priv->reset = 0 ; + } ; + + priv->in_count = data->input_frames * priv->channels ; + priv->out_count = data->output_frames * priv->channels ; + priv->in_used = priv->out_gen = 0 ; + + src_ratio = psrc->last_ratio ; + + if (is_bad_src_ratio (src_ratio)) + return SRC_ERR_BAD_INTERNAL_STATE ; + + input_index = psrc->last_position ; + + /* Calculate samples before first sample in input array. */ + while (input_index < 1.0 && priv->out_gen < priv->out_count) + { + if (priv->in_used + priv->channels * input_index >= priv->in_count) + break ; + + if (priv->out_count > 0 && fabs (psrc->last_ratio - data->src_ratio) > SRC_MIN_RATIO_DIFF) + src_ratio = psrc->last_ratio + priv->out_gen * (data->src_ratio - psrc->last_ratio) / priv->out_count ; + + for (ch = 0 ; ch < priv->channels ; ch++) + { data->data_out [priv->out_gen] = priv->last_value [ch] ; + priv->out_gen ++ ; + } ; + + /* Figure out the next index. */ + input_index += 1.0 / src_ratio ; + } ; + + rem = fmod_one (input_index) ; + priv->in_used += priv->channels * lrint (input_index - rem) ; + input_index = rem ; + + /* Main processing loop. */ + while (priv->out_gen < priv->out_count && priv->in_used + priv->channels * input_index <= priv->in_count) + { + if (priv->out_count > 0 && fabs (psrc->last_ratio - data->src_ratio) > SRC_MIN_RATIO_DIFF) + src_ratio = psrc->last_ratio + priv->out_gen * (data->src_ratio - psrc->last_ratio) / priv->out_count ; + + for (ch = 0 ; ch < priv->channels ; ch++) + { data->data_out [priv->out_gen] = data->data_in [priv->in_used - priv->channels + ch] ; + priv->out_gen ++ ; + } ; + + /* Figure out the next index. */ + input_index += 1.0 / src_ratio ; + rem = fmod_one (input_index) ; + + priv->in_used += priv->channels * lrint (input_index - rem) ; + input_index = rem ; + } ; + + if (priv->in_used > priv->in_count) + { input_index += (priv->in_used - priv->in_count) / priv->channels ; + priv->in_used = priv->in_count ; + } ; + + psrc->last_position = input_index ; + + if (priv->in_used > 0) + for (ch = 0 ; ch < priv->channels ; ch++) + priv->last_value [ch] = data->data_in [priv->in_used - priv->channels + ch] ; + + /* Save current ratio rather then target ratio. */ + psrc->last_ratio = src_ratio ; + + data->input_frames_used = priv->in_used / priv->channels ; + data->output_frames_gen = priv->out_gen / priv->channels ; + + return SRC_ERR_NO_ERROR ; +} /* zoh_vari_process */ + +/*------------------------------------------------------------------------------ +*/ + +const char* +zoh_get_name (int src_enum) +{ + if (src_enum == SRC_ZERO_ORDER_HOLD) + return "ZOH Interpolator" ; + + return NULL ; +} /* zoh_get_name */ + +const char* +zoh_get_description (int src_enum) +{ + if (src_enum == SRC_ZERO_ORDER_HOLD) + return "Zero order hold interpolator, very fast, poor quality." ; + + return NULL ; +} /* zoh_get_descrition */ + +int +zoh_set_converter (SRC_PRIVATE *psrc, int src_enum) +{ ZOH_DATA *priv = NULL ; + + if (src_enum != SRC_ZERO_ORDER_HOLD) + return SRC_ERR_BAD_CONVERTER ; + + if (psrc->private_data != NULL) + { free (psrc->private_data) ; + psrc->private_data = NULL ; + } ; + + if (psrc->private_data == NULL) + { priv = calloc (1, sizeof (*priv) + psrc->channels * sizeof (float)) ; + psrc->private_data = priv ; + } ; + + if (priv == NULL) + return SRC_ERR_MALLOC_FAILED ; + + priv->zoh_magic_marker = ZOH_MAGIC_MARKER ; + priv->channels = psrc->channels ; + + psrc->const_process = zoh_vari_process ; + psrc->vari_process = zoh_vari_process ; + psrc->reset = zoh_reset ; + + zoh_reset (psrc) ; + + return SRC_ERR_NO_ERROR ; +} /* zoh_set_converter */ + +/*=================================================================================== +*/ + +static void +zoh_reset (SRC_PRIVATE *psrc) +{ ZOH_DATA *priv ; + + priv = (ZOH_DATA*) psrc->private_data ; + if (priv == NULL) + return ; + + priv->channels = psrc->channels ; + priv->reset = 1 ; + memset (priv->last_value, 0, sizeof (priv->last_value [0]) * priv->channels) ; + + return ; +} /* zoh_reset */ +