ref: 709b0069c55ac1f3b073f9b5dd475a07f6eabb8e
dir: /src/src_zoh.c/
/* ** Copyright (C) 2002-2007 Erik de Castro Lopo <[email protected]> ** ** This program is free software; you can redistribute it and/or modify ** it under the terms of the GNU General Public License as published by ** the Free Software Foundation; either version 2 of the License, or ** (at your option) any later version. ** ** This program is distributed in the hope that it will be useful, ** but WITHOUT ANY WARRANTY; without even the implied warranty of ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ** GNU General Public License for more details. ** ** You should have received a copy of the GNU General Public License ** along with this program; if not, write to the Free Software ** Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA. */ /* ** This code is part of Secret Rabibt Code aka libsamplerate. A commercial ** use license for this code is available, please see: ** http://www.mega-nerd.com/SRC/procedure.html */ #include <stdio.h> #include <stdlib.h> #include <string.h> #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 *zoh ; double src_ratio, input_index, rem ; int ch ; if (psrc->private_data == NULL) return SRC_ERR_NO_PRIVATE ; zoh = (ZOH_DATA*) psrc->private_data ; if (zoh->reset) { /* If we have just been reset, set the last_value data. */ for (ch = 0 ; ch < zoh->channels ; ch++) zoh->last_value [ch] = data->data_in [ch] ; zoh->reset = 0 ; } ; zoh->in_count = data->input_frames * zoh->channels ; zoh->out_count = data->output_frames * zoh->channels ; zoh->in_used = zoh->out_gen = 0 ; src_ratio = psrc->last_ratio ; input_index = psrc->last_position ; /* Calculate samples before first sample in input array. */ while (input_index < 1.0 && zoh->out_gen < zoh->out_count) { if (zoh->in_used + zoh->channels * input_index >= zoh->in_count) break ; if (zoh->out_count > 0 && fabs (psrc->last_ratio - data->src_ratio) > SRC_MIN_RATIO_DIFF) src_ratio = psrc->last_ratio + zoh->out_gen * (data->src_ratio - psrc->last_ratio) / zoh->out_count ; for (ch = 0 ; ch < zoh->channels ; ch++) { data->data_out [zoh->out_gen] = zoh->last_value [ch] ; zoh->out_gen ++ ; } ; /* Figure out the next index. */ input_index += 1.0 / src_ratio ; } ; rem = fmod_one (input_index) ; zoh->in_used += zoh->channels * lrint (input_index - rem) ; input_index = rem ; /* Main processing loop. */ while (zoh->out_gen < zoh->out_count && zoh->in_used + zoh->channels * input_index <= zoh->in_count) { if (zoh->out_count > 0 && fabs (psrc->last_ratio - data->src_ratio) > SRC_MIN_RATIO_DIFF) src_ratio = psrc->last_ratio + zoh->out_gen * (data->src_ratio - psrc->last_ratio) / zoh->out_count ; for (ch = 0 ; ch < zoh->channels ; ch++) { data->data_out [zoh->out_gen] = data->data_in [zoh->in_used - zoh->channels + ch] ; zoh->out_gen ++ ; } ; /* Figure out the next index. */ input_index += 1.0 / src_ratio ; rem = fmod_one (input_index) ; zoh->in_used += zoh->channels * lrint (input_index - rem) ; input_index = rem ; } ; if (zoh->in_used > zoh->in_count) { input_index += (zoh->in_used - zoh->in_count) / zoh->channels ; zoh->in_used = zoh->in_count ; } ; psrc->last_position = input_index ; if (zoh->in_used > 0) for (ch = 0 ; ch < zoh->channels ; ch++) zoh->last_value [ch] = data->data_in [zoh->in_used - zoh->channels + ch] ; /* Save current ratio rather then target ratio. */ psrc->last_ratio = src_ratio ; data->input_frames_used = zoh->in_used / zoh->channels ; data->output_frames_gen = zoh->out_gen / zoh->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 *zoh = NULL ; if (src_enum != SRC_ZERO_ORDER_HOLD) return SRC_ERR_BAD_CONVERTER ; if (psrc->private_data != NULL) { zoh = (ZOH_DATA*) psrc->private_data ; if (zoh->zoh_magic_marker != ZOH_MAGIC_MARKER) { free (psrc->private_data) ; psrc->private_data = NULL ; } ; } ; if (psrc->private_data == NULL) { zoh = calloc (1, sizeof (*zoh) + psrc->channels * sizeof (float)) ; if (zoh == NULL) return SRC_ERR_MALLOC_FAILED ; psrc->private_data = zoh ; } ; zoh->zoh_magic_marker = ZOH_MAGIC_MARKER ; zoh->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 *zoh ; zoh = (ZOH_DATA*) psrc->private_data ; if (zoh == NULL) return ; zoh->channels = psrc->channels ; zoh->reset = 1 ; memset (zoh->last_value, 0, sizeof (zoh->last_value [0]) * zoh->channels) ; return ; } /* zoh_reset */