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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 <stdio.h> | |
10 | #include <stdlib.h> | |
11 | #include <string.h> | |
12 | ||
13 | #include "config.h" | |
14 | #include "float_cast.h" | |
15 | #include "common.h" | |
16 | ||
17 | static int zoh_vari_process (SRC_PRIVATE *psrc, SRC_DATA *data) ; | |
18 | static void zoh_reset (SRC_PRIVATE *psrc) ; | |
19 | ||
20 | /*======================================================================================== | |
21 | */ | |
22 | ||
23 | #define ZOH_MAGIC_MARKER MAKE_MAGIC ('s', 'r', 'c', 'z', 'o', 'h') | |
24 | ||
25 | typedef struct | |
26 | { int zoh_magic_marker ; | |
27 | int channels ; | |
28 | int reset ; | |
29 | long in_count, in_used ; | |
30 | long out_count, out_gen ; | |
31 | float last_value [1] ; | |
32 | } ZOH_DATA ; | |
33 | ||
34 | /*---------------------------------------------------------------------------------------- | |
35 | */ | |
36 | ||
37 | static int | |
38 | zoh_vari_process (SRC_PRIVATE *psrc, SRC_DATA *data) | |
39 | { ZOH_DATA *priv ; | |
40 | double src_ratio, input_index, rem ; | |
41 | int ch ; | |
42 | ||
43 | if (data->input_frames <= 0) | |
44 | return SRC_ERR_NO_ERROR ; | |
45 | ||
46 | if (psrc->private_data == NULL) | |
47 | return SRC_ERR_NO_PRIVATE ; | |
48 | ||
49 | priv = (ZOH_DATA*) psrc->private_data ; | |
50 | ||
51 | if (priv->reset) | |
52 | { /* If we have just been reset, set the last_value data. */ | |
53 | for (ch = 0 ; ch < priv->channels ; ch++) | |
54 | priv->last_value [ch] = data->data_in [ch] ; | |
55 | priv->reset = 0 ; | |
56 | } ; | |
57 | ||
58 | priv->in_count = data->input_frames * priv->channels ; | |
59 | priv->out_count = data->output_frames * priv->channels ; | |
60 | priv->in_used = priv->out_gen = 0 ; | |
61 | ||
62 | src_ratio = psrc->last_ratio ; | |
63 | ||
64 | if (is_bad_src_ratio (src_ratio)) | |
65 | return SRC_ERR_BAD_INTERNAL_STATE ; | |
66 | ||
67 | input_index = psrc->last_position ; | |
68 | ||
69 | /* Calculate samples before first sample in input array. */ | |
70 | while (input_index < 1.0 && priv->out_gen < priv->out_count) | |
71 | { | |
72 | if (priv->in_used + priv->channels * input_index >= priv->in_count) | |
73 | break ; | |
74 | ||
75 | if (priv->out_count > 0 && fabs (psrc->last_ratio - data->src_ratio) > SRC_MIN_RATIO_DIFF) | |
76 | src_ratio = psrc->last_ratio + priv->out_gen * (data->src_ratio - psrc->last_ratio) / priv->out_count ; | |
77 | ||
78 | for (ch = 0 ; ch < priv->channels ; ch++) | |
79 | { data->data_out [priv->out_gen] = priv->last_value [ch] ; | |
80 | priv->out_gen ++ ; | |
81 | } ; | |
82 | ||
83 | /* Figure out the next index. */ | |
84 | input_index += 1.0 / src_ratio ; | |
85 | } ; | |
86 | ||
87 | rem = fmod_one (input_index) ; | |
88 | priv->in_used += priv->channels * lrint (input_index - rem) ; | |
89 | input_index = rem ; | |
90 | ||
91 | /* Main processing loop. */ | |
92 | while (priv->out_gen < priv->out_count && priv->in_used + priv->channels * input_index <= priv->in_count) | |
93 | { | |
94 | if (priv->out_count > 0 && fabs (psrc->last_ratio - data->src_ratio) > SRC_MIN_RATIO_DIFF) | |
95 | src_ratio = psrc->last_ratio + priv->out_gen * (data->src_ratio - psrc->last_ratio) / priv->out_count ; | |
96 | ||
97 | for (ch = 0 ; ch < priv->channels ; ch++) | |
98 | { data->data_out [priv->out_gen] = data->data_in [priv->in_used - priv->channels + ch] ; | |
99 | priv->out_gen ++ ; | |
100 | } ; | |
101 | ||
102 | /* Figure out the next index. */ | |
103 | input_index += 1.0 / src_ratio ; | |
104 | rem = fmod_one (input_index) ; | |
105 | ||
106 | priv->in_used += priv->channels * lrint (input_index - rem) ; | |
107 | input_index = rem ; | |
108 | } ; | |
109 | ||
110 | if (priv->in_used > priv->in_count) | |
111 | { input_index += (priv->in_used - priv->in_count) / priv->channels ; | |
112 | priv->in_used = priv->in_count ; | |
113 | } ; | |
114 | ||
115 | psrc->last_position = input_index ; | |
116 | ||
117 | if (priv->in_used > 0) | |
118 | for (ch = 0 ; ch < priv->channels ; ch++) | |
119 | priv->last_value [ch] = data->data_in [priv->in_used - priv->channels + ch] ; | |
120 | ||
121 | /* Save current ratio rather then target ratio. */ | |
122 | psrc->last_ratio = src_ratio ; | |
123 | ||
124 | data->input_frames_used = priv->in_used / priv->channels ; | |
125 | data->output_frames_gen = priv->out_gen / priv->channels ; | |
126 | ||
127 | return SRC_ERR_NO_ERROR ; | |
128 | } /* zoh_vari_process */ | |
129 | ||
130 | /*------------------------------------------------------------------------------ | |
131 | */ | |
132 | ||
133 | const char* | |
134 | zoh_get_name (int src_enum) | |
135 | { | |
136 | if (src_enum == SRC_ZERO_ORDER_HOLD) | |
137 | return "ZOH Interpolator" ; | |
138 | ||
139 | return NULL ; | |
140 | } /* zoh_get_name */ | |
141 | ||
142 | const char* | |
143 | zoh_get_description (int src_enum) | |
144 | { | |
145 | if (src_enum == SRC_ZERO_ORDER_HOLD) | |
146 | return "Zero order hold interpolator, very fast, poor quality." ; | |
147 | ||
148 | return NULL ; | |
149 | } /* zoh_get_descrition */ | |
150 | ||
151 | int | |
152 | zoh_set_converter (SRC_PRIVATE *psrc, int src_enum) | |
153 | { ZOH_DATA *priv = NULL ; | |
154 | ||
155 | if (src_enum != SRC_ZERO_ORDER_HOLD) | |
156 | return SRC_ERR_BAD_CONVERTER ; | |
157 | ||
158 | if (psrc->private_data != NULL) | |
159 | { free (psrc->private_data) ; | |
160 | psrc->private_data = NULL ; | |
161 | } ; | |
162 | ||
163 | if (psrc->private_data == NULL) | |
164 | { priv = calloc (1, sizeof (*priv) + psrc->channels * sizeof (float)) ; | |
165 | psrc->private_data = priv ; | |
166 | } ; | |
167 | ||
168 | if (priv == NULL) | |
169 | return SRC_ERR_MALLOC_FAILED ; | |
170 | ||
171 | priv->zoh_magic_marker = ZOH_MAGIC_MARKER ; | |
172 | priv->channels = psrc->channels ; | |
173 | ||
174 | psrc->const_process = zoh_vari_process ; | |
175 | psrc->vari_process = zoh_vari_process ; | |
176 | psrc->reset = zoh_reset ; | |
177 | ||
178 | zoh_reset (psrc) ; | |
179 | ||
180 | return SRC_ERR_NO_ERROR ; | |
181 | } /* zoh_set_converter */ | |
182 | ||
183 | /*=================================================================================== | |
184 | */ | |
185 | ||
186 | static void | |
187 | zoh_reset (SRC_PRIVATE *psrc) | |
188 | { ZOH_DATA *priv ; | |
189 | ||
190 | priv = (ZOH_DATA*) psrc->private_data ; | |
191 | if (priv == NULL) | |
192 | return ; | |
193 | ||
194 | priv->channels = psrc->channels ; | |
195 | priv->reset = 1 ; | |
196 | memset (priv->last_value, 0, sizeof (priv->last_value [0]) * priv->channels) ; | |
197 | ||
198 | return ; | |
199 | } /* zoh_reset */ | |
200 |