📄 f411_vr_dpcm.lst
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C51 COMPILER V7.06 F411_VR_DPCM 02/18/2009 16:30:49 PAGE 1
C51 COMPILER V7.06, COMPILATION OF MODULE F411_VR_DPCM
OBJECT MODULE PLACED IN F411_VR_DPCM.OBJ
COMPILER INVOKED BY: C:\Keil\C51\BIN\C51.EXE F411_VR_DPCM.c BROWSE DEBUG OBJECTEXTEND
stmt level source
1 //-----------------------------------------------------------------------------
2 // F411_VR_DPCM.c
3 //-----------------------------------------------------------------------------
4 // Copyright 2006 Silicon Laboratories, Inc.
5 // http://www.silabs.com
6 //
7 // Program Description:
8 //
9 // This file contains the DPCM encoding and decoding functions.
10 //
11 // NOTE: For another reference for DPCM, please see Chipcon's app note an026.
12 //
13 // NOTE: The calling function must have the same register context as the DCPM
14 // functions, so it must either have the keyword "using 2" or all "using 2"
15 // keywords for the DPCM functions need to be removed
16 //
17 // How To Use: See Readme.txt
18 //
19 // FID: 41X000006
20 // Target: C8051F411
21 // Tool chain: Keil C51 7.50 / Keil EVAL C51
22 // Silicon Laboratories IDE version 2.6
23 // Project Name: F411_VR
24 //
25 // Release 1.3
26 // -All changes by TP
27 // -02 Feb 2006
28 // -project version updated, no changes to this file
29 //
30 // Release 1.2
31 // -All changes by TP
32 // -21 Nov 2005
33 // -expanded the 4-bit codes to 6 bits for the 12-bit ADC
34 //
35 // Release 1.1
36 // -All changes by TP
37 // -16 Aug 2004
38 // -project version updated, no changes to this file
39 //
40 // Release 1.0
41 // -Initial Revision (TP)
42 // -15 AUG 2004
43 //
44
45 //-----------------------------------------------------------------------------
46 // Includes
47 //-----------------------------------------------------------------------------
48 #include <c8051f410.h> // SFR declarations
49
50 //-----------------------------------------------------------------------------
51 // Global CONSTANTS
52 //-----------------------------------------------------------------------------
53
54 // 12-bit quantization codes (6 bits, so 64 codes total = 31 positive, 31
55 // negative, and 2 zeroes)
C51 COMPILER V7.06 F411_VR_DPCM 02/18/2009 16:30:49 PAGE 2
56 #define quant1 1
57 #define quant2 2
58 #define quant3 4
59 #define quant4 7
60 #define quant5 11
61 #define quant6 16
62 #define quant7 22
63 #define quant8 29
64 #define quant9 37
65 #define quant10 46
66 #define quant11 56
67 #define quant12 67
68 #define quant13 79
69 #define quant14 92
70 #define quant15 106
71 #define quant16 130
72 #define quant17 146
73 #define quant18 163
74 #define quant19 181
75 #define quant20 200
76 #define quant21 220
77 #define quant22 241
78 #define quant23 263
79 #define quant24 286
80 #define quant25 310
81 #define quant26 335
82 #define quant27 361
83 #define quant28 388
84 #define quant29 416
85 #define quant30 512
86 #define quant31 1024
87
88 // the mapping from quantization values to dpcm codes (array index)
89 xdata short Q_VALUES[64] = {0, // 0
90 -quant31, // 1
91 -quant30, // 2
92 -quant29, // 3
93 -quant28, // 4
94 -quant27, // 5
95 -quant26, // 6
96 -quant25, // 7
97 -quant24, // 8
98 -quant23, // 9
99 -quant22, // 10
100 -quant21, // 11
101 -quant20, // 12
102 -quant19, // 13
103 -quant18, // 14
104 -quant17, // 15
105 -quant16, // 16 negative middle
106 -quant15, // 17
107 -quant14, // 18
108 -quant13, // 19
109 -quant12, // 20
110 -quant11, // 21
111 -quant10, // 22
112 -quant9, // 23
113 -quant8, // 24
114 -quant7, // 25
115 -quant6, // 26
116 -quant5, // 27
117 -quant4, // 28
C51 COMPILER V7.06 F411_VR_DPCM 02/18/2009 16:30:49 PAGE 3
118 -quant3, // 29
119 -quant2, // 30
120 -quant1, // 31
121 0, // 32
122 quant1, // 33
123 quant2, // 34
124 quant3, // 35
125 quant4, // 36
126 quant5, // 37
127 quant6, // 38
128 quant7, // 39
129 quant8, // 40
130 quant9, // 41
131 quant10, // 42
132 quant11, // 43
133 quant12, // 44
134 quant13, // 45
135 quant14, // 46
136 quant15, // 47
137 quant16, // 48 positive middle
138 quant17, // 49
139 quant18, // 50
140 quant19, // 51
141 quant20, // 52
142 quant21, // 53
143 quant22, // 54
144 quant23, // 55
145 quant24, // 56
146 quant25, // 57
147 quant26, // 58
148 quant27, // 59
149 quant28, // 60
150 quant29, // 61
151 quant30, // 62
152 quant31}; // 63
153
154 //-----------------------------------------------------------------------------
155 // Function PROTOTYPES
156 //-----------------------------------------------------------------------------
157 unsigned char DPCM_Encode (short sample_diff);
158 short DPCM_Decode (unsigned char dpcm_code);
159
160 //-----------------------------------------------------------------------------
161 // DPCM_Encode
162 //-----------------------------------------------------------------------------
163 //
164 // Return Value :
165 // 1) char dpcm_code - the 6-bit quantized DPCM code
166 // range is positive range of 6-bit value: 0 to 63
167 // Parameters :
168 // 1) short sample_diff - the difference between the predicted value and
169 // the sample from the ADC
170 // range is: -4096 to 4095 (difference of 12-bit values)
171 //
172 // Encode the sample using DPCM compression.
173 //
174 // The coding uses the following scheme (0 is unused) for an 8-bit sample:
175 //
176 // code: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
177 // q value: -64 -32 -16 -8 -4 -2 -1 0 1 2 4 8 16 32 64
178 //
179 // The difference will be rounded down if positive and rounded up if
C51 COMPILER V7.06 F411_VR_DPCM 02/18/2009 16:30:49 PAGE 4
180 // negative (i.e. 41 => 32, and -41 => -32).
181 //
182 // NOTE: the calling function must have the same register context, so it must
183 // either have the keyword "using 2" or all "using 2" keywords need to be
184 // removed
185 //
186 unsigned char DPCM_Encode (short sample_diff) using 2
187 {
188 1 short sample_diff_us;
189 1 unsigned char dpcm_code;
190 1
191 1 // determine if the difference is positive or negative
192 1 if (sample_diff < 0)
193 1 {
194 2 sample_diff_us = -sample_diff; // use the absolute value
195 2 }
196 1 else
197 1 {
198 2 sample_diff_us = sample_diff;
199 2 }
200 1
201 1 // narrow down which bits need to be set to use the proper quantization code
202 1 // using a binary search algorithm (divide in halves)
203 1 // the sign of the difference no longer matters
204 1
205 1 // first tier
206 1 if (sample_diff_us >= quant16)
207 1 {
208 2 // second tier
209 2 if (sample_diff_us >= quant24)
210 2 {
211 3 // third tier
212 3 if (sample_diff_us >= quant28)
213 3 {
214 4 // fourth tier
215 4 if (sample_diff_us >= quant30)
216 4 {
217 5 // fifth tier
218 5 if (sample_diff_us >= quant31)
219 5 {
220 6 dpcm_code = 63;
221 6 }
222 5 // fifth tier
223 5 else
224 5 {
225 6 dpcm_code = 62;
226 6 }
227 5 }
228 4 // fourth tier
229 4 else
230 4 {
231 5 // fifth tier
232 5 if (sample_diff_us >= quant29)
233 5 {
234 6 dpcm_code = 61;
235 6 }
236 5 // fifth tier
237 5 else
238 5 {
239 6 dpcm_code = 60;
240 6 }
241 5 }
C51 COMPILER V7.06 F411_VR_DPCM 02/18/2009 16:30:49 PAGE 5
242 4 }
243 3 // third tier
244 3 else
245 3 {
246 4 // fourth tier
247 4 if (sample_diff_us >= quant26)
248 4 {
249 5 // fifth tier
250 5 if (sample_diff_us >= quant27)
251 5 {
252 6 dpcm_code = 59;
253 6 }
254 5 // fifth tier
255 5 else
256 5 {
257 6 dpcm_code = 58;
258 6 }
259 5 }
260 4 // fourth tier
261 4 else
262 4 {
263 5 // fifth tier
264 5 if (sample_diff_us >= quant25)
265 5 {
266 6 dpcm_code = 57;
267 6 }
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