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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 linear_vari_process (SRC_PRIVATE *psrc, SRC_DATA *data) ; | |
18 | static void linear_reset (SRC_PRIVATE *psrc) ; | |
19 | ||
20 | /*======================================================================================== | |
21 | */ | |
22 | ||
23 | #define LINEAR_MAGIC_MARKER MAKE_MAGIC ('l', 'i', 'n', 'e', 'a', 'r') | |
24 | ||
25 | #define SRC_DEBUG 0 | |
26 | ||
27 | typedef struct | |
28 | { int linear_magic_marker ; | |
29 | int channels ; | |
30 | int reset ; | |
31 | long in_count, in_used ; | |
32 | long out_count, out_gen ; | |
33 | float last_value [1] ; | |
34 | } LINEAR_DATA ; | |
35 | ||
36 | /*---------------------------------------------------------------------------------------- | |
37 | */ | |
38 | ||
39 | static int | |
40 | linear_vari_process (SRC_PRIVATE *psrc, SRC_DATA *data) | |
41 | { LINEAR_DATA *priv ; | |
42 | double src_ratio, input_index, rem ; | |
43 | int ch ; | |
44 | ||
45 | if (data->input_frames <= 0) | |
46 | return SRC_ERR_NO_ERROR ; | |
47 | ||
48 | if (psrc->private_data == NULL) | |
49 | return SRC_ERR_NO_PRIVATE ; | |
50 | ||
51 | priv = (LINEAR_DATA*) psrc->private_data ; | |
52 | ||
53 | if (priv->reset) | |
54 | { /* If we have just been reset, set the last_value data. */ | |
55 | for (ch = 0 ; ch < priv->channels ; ch++) | |
56 | priv->last_value [ch] = data->data_in [ch] ; | |
57 | priv->reset = 0 ; | |
58 | } ; | |
59 | ||
60 | priv->in_count = data->input_frames * priv->channels ; | |
61 | priv->out_count = data->output_frames * priv->channels ; | |
62 | priv->in_used = priv->out_gen = 0 ; | |
63 | ||
64 | src_ratio = psrc->last_ratio ; | |
65 | ||
66 | if (is_bad_src_ratio (src_ratio)) | |
67 | return SRC_ERR_BAD_INTERNAL_STATE ; | |
68 | ||
69 | input_index = psrc->last_position ; | |
70 | ||
71 | /* Calculate samples before first sample in input array. */ | |
72 | while (input_index < 1.0 && priv->out_gen < priv->out_count) | |
73 | { | |
74 | if (priv->in_used + priv->channels * (1.0 + input_index) >= priv->in_count) | |
75 | break ; | |
76 | ||
77 | if (priv->out_count > 0 && fabs (psrc->last_ratio - data->src_ratio) > SRC_MIN_RATIO_DIFF) | |
78 | src_ratio = psrc->last_ratio + priv->out_gen * (data->src_ratio - psrc->last_ratio) / priv->out_count ; | |
79 | ||
80 | for (ch = 0 ; ch < priv->channels ; ch++) | |
81 | { data->data_out [priv->out_gen] = (float) (priv->last_value [ch] + input_index * | |
82 | (data->data_in [ch] - priv->last_value [ch])) ; | |
83 | priv->out_gen ++ ; | |
84 | } ; | |
85 | ||
86 | /* Figure out the next index. */ | |
87 | input_index += 1.0 / src_ratio ; | |
88 | } ; | |
89 | ||
90 | rem = fmod_one (input_index) ; | |
91 | priv->in_used += priv->channels * lrint (input_index - rem) ; | |
92 | input_index = rem ; | |
93 | ||
94 | /* Main processing loop. */ | |
95 | while (priv->out_gen < priv->out_count && priv->in_used + priv->channels * input_index < priv->in_count) | |
96 | { | |
97 | if (priv->out_count > 0 && fabs (psrc->last_ratio - data->src_ratio) > SRC_MIN_RATIO_DIFF) | |
98 | src_ratio = psrc->last_ratio + priv->out_gen * (data->src_ratio - psrc->last_ratio) / priv->out_count ; | |
99 | ||
100 | if (SRC_DEBUG && priv->in_used < priv->channels && input_index < 1.0) | |
101 | { printf ("Whoops!!!! in_used : %ld channels : %d input_index : %f\n", priv->in_used, priv->channels, input_index) ; | |
102 | exit (1) ; | |
103 | } ; | |
104 | ||
105 | for (ch = 0 ; ch < priv->channels ; ch++) | |
106 | { data->data_out [priv->out_gen] = (float) (data->data_in [priv->in_used - priv->channels + ch] + input_index * | |
107 | (data->data_in [priv->in_used + ch] - data->data_in [priv->in_used - priv->channels + ch])) ; | |
108 | priv->out_gen ++ ; | |
109 | } ; | |
110 | ||
111 | /* Figure out the next index. */ | |
112 | input_index += 1.0 / src_ratio ; | |
113 | rem = fmod_one (input_index) ; | |
114 | ||
115 | priv->in_used += priv->channels * lrint (input_index - rem) ; | |
116 | input_index = rem ; | |
117 | } ; | |
118 | ||
119 | if (priv->in_used > priv->in_count) | |
120 | { input_index += (priv->in_used - priv->in_count) / priv->channels ; | |
121 | priv->in_used = priv->in_count ; | |
122 | } ; | |
123 | ||
124 | psrc->last_position = input_index ; | |
125 | ||
126 | if (priv->in_used > 0) | |
127 | for (ch = 0 ; ch < priv->channels ; ch++) | |
128 | priv->last_value [ch] = data->data_in [priv->in_used - priv->channels + ch] ; | |
129 | ||
130 | /* Save current ratio rather then target ratio. */ | |
131 | psrc->last_ratio = src_ratio ; | |
132 | ||
133 | data->input_frames_used = priv->in_used / priv->channels ; | |
134 | data->output_frames_gen = priv->out_gen / priv->channels ; | |
135 | ||
136 | return SRC_ERR_NO_ERROR ; | |
137 | } /* linear_vari_process */ | |
138 | ||
139 | /*------------------------------------------------------------------------------ | |
140 | */ | |
141 | ||
142 | const char* | |
143 | linear_get_name (int src_enum) | |
144 | { | |
145 | if (src_enum == SRC_LINEAR) | |
146 | return "Linear Interpolator" ; | |
147 | ||
148 | return NULL ; | |
149 | } /* linear_get_name */ | |
150 | ||
151 | const char* | |
152 | linear_get_description (int src_enum) | |
153 | { | |
154 | if (src_enum == SRC_LINEAR) | |
155 | return "Linear interpolator, very fast, poor quality." ; | |
156 | ||
157 | return NULL ; | |
158 | } /* linear_get_descrition */ | |
159 | ||
160 | int | |
161 | linear_set_converter (SRC_PRIVATE *psrc, int src_enum) | |
162 | { LINEAR_DATA *priv = NULL ; | |
163 | ||
164 | if (src_enum != SRC_LINEAR) | |
165 | return SRC_ERR_BAD_CONVERTER ; | |
166 | ||
167 | if (psrc->private_data != NULL) | |
168 | { free (psrc->private_data) ; | |
169 | psrc->private_data = NULL ; | |
170 | } ; | |
171 | ||
172 | if (psrc->private_data == NULL) | |
173 | { priv = calloc (1, sizeof (*priv) + psrc->channels * sizeof (float)) ; | |
174 | psrc->private_data = priv ; | |
175 | } ; | |
176 | ||
177 | if (priv == NULL) | |
178 | return SRC_ERR_MALLOC_FAILED ; | |
179 | ||
180 | priv->linear_magic_marker = LINEAR_MAGIC_MARKER ; | |
181 | priv->channels = psrc->channels ; | |
182 | ||
183 | psrc->const_process = linear_vari_process ; | |
184 | psrc->vari_process = linear_vari_process ; | |
185 | psrc->reset = linear_reset ; | |
186 | ||
187 | linear_reset (psrc) ; | |
188 | ||
189 | return SRC_ERR_NO_ERROR ; | |
190 | } /* linear_set_converter */ | |
191 | ||
192 | /*=================================================================================== | |
193 | */ | |
194 | ||
195 | static void | |
196 | linear_reset (SRC_PRIVATE *psrc) | |
197 | { LINEAR_DATA *priv = NULL ; | |
198 | ||
199 | priv = (LINEAR_DATA*) psrc->private_data ; | |
200 | if (priv == NULL) | |
201 | return ; | |
202 | ||
203 | priv->channels = psrc->channels ; | |
204 | priv->reset = 1 ; | |
205 | memset (priv->last_value, 0, sizeof (priv->last_value [0]) * priv->channels) ; | |
206 | ||
207 | return ; | |
208 | } /* linear_reset */ | |
209 |