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1 : | edgomez | 1.6 | /* idct.c, inverse fast discrete cosine transform */ |
2 : | |||
3 : | /* Copyright (C) 1996, MPEG Software Simulation Group. All Rights Reserved. */ | ||
4 : | |||
5 : | /* | ||
6 : | * Disclaimer of Warranty | ||
7 : | chl | 1.3 | * |
8 : | edgomez | 1.6 | * These software programs are available to the user without any license fee or |
9 : | * royalty on an "as is" basis. The MPEG Software Simulation Group disclaims | ||
10 : | * any and all warranties, whether express, implied, or statuary, including any | ||
11 : | * implied warranties or merchantability or of fitness for a particular | ||
12 : | * purpose. In no event shall the copyright-holder be liable for any | ||
13 : | * incidental, punitive, or consequential damages of any kind whatsoever | ||
14 : | * arising from the use of these programs. | ||
15 : | * | ||
16 : | * This disclaimer of warranty extends to the user of these programs and user's | ||
17 : | * customers, employees, agents, transferees, successors, and assigns. | ||
18 : | * | ||
19 : | * The MPEG Software Simulation Group does not represent or warrant that the | ||
20 : | * programs furnished hereunder are free of infringement of any third-party | ||
21 : | * patents. | ||
22 : | * | ||
23 : | * Commercial implementations of MPEG-1 and MPEG-2 video, including shareware, | ||
24 : | * are subject to royalty fees to patent holders. Many of these patents are | ||
25 : | * general enough such that they are unavoidable regardless of implementation | ||
26 : | * design. | ||
27 : | * | ||
28 : | * MPEG2AVI | ||
29 : | * -------- | ||
30 : | * v0.16B33 renamed the initialization function to init_idct_int32() | ||
31 : | * v0.16B32 removed the unused idct_row() and idct_col() functions | ||
32 : | * v0.16B3 changed var declarations to static, to enforce data align | ||
33 : | * v0.16B22 idct_FAST() renamed to idct_int32() | ||
34 : | * also merged idct_FAST() into a single function, to help VC++ | ||
35 : | * optimize it. | ||
36 : | * | ||
37 : | * v0.14 changed int to long, to avoid confusion when compiling on x86 | ||
38 : | * platform ( in VC++ "int" -> 32bits ) | ||
39 : | */ | ||
40 : | Isibaar | 1.1 | |
41 : | /**********************************************************/ | ||
42 : | /* inverse two dimensional DCT, Chen-Wang algorithm */ | ||
43 : | /* (cf. IEEE ASSP-32, pp. 803-816, Aug. 1984) */ | ||
44 : | /* 32-bit integer arithmetic (8 bit coefficients) */ | ||
45 : | /* 11 mults, 29 adds per DCT */ | ||
46 : | /* sE, 18.8.91 */ | ||
47 : | /**********************************************************/ | ||
48 : | /* coefficients extended to 12 bit for IEEE1180-1990 */ | ||
49 : | /* compliance sE, 2.1.94 */ | ||
50 : | /**********************************************************/ | ||
51 : | |||
52 : | /* this code assumes >> to be a two's-complement arithmetic */ | ||
53 : | /* right shift: (-2)>>1 == -1 , (-3)>>1 == -2 */ | ||
54 : | |||
55 : | #include "idct.h" | ||
56 : | |||
57 : | edgomez | 1.2 | #define W1 2841 /* 2048*sqrt(2)*cos(1*pi/16) */ |
58 : | #define W2 2676 /* 2048*sqrt(2)*cos(2*pi/16) */ | ||
59 : | #define W3 2408 /* 2048*sqrt(2)*cos(3*pi/16) */ | ||
60 : | #define W5 1609 /* 2048*sqrt(2)*cos(5*pi/16) */ | ||
61 : | #define W6 1108 /* 2048*sqrt(2)*cos(6*pi/16) */ | ||
62 : | #define W7 565 /* 2048*sqrt(2)*cos(7*pi/16) */ | ||
63 : | Isibaar | 1.1 | |
64 : | /* private data */ | ||
65 : | edgomez | 1.2 | static short iclip[1024]; /* clipping table */ |
66 : | Isibaar | 1.1 | static short *iclp; |
67 : | |||
68 : | /* private prototypes */ | ||
69 : | |||
70 : | /* row (horizontal) IDCT | ||
71 : | * | ||
72 : | * 7 pi 1 | ||
73 : | * dst[k] = sum c[l] * src[l] * cos( -- * ( k + - ) * l ) | ||
74 : | * l=0 8 2 | ||
75 : | * | ||
76 : | * where: c[0] = 128 | ||
77 : | * c[1..7] = 128*sqrt(2) | ||
78 : | */ | ||
79 : | |||
80 : | edgomez | 1.6.2.1 | #if 0 |
81 : | Isibaar | 1.1 | static void idctrow(blk) |
82 : | short *blk; | ||
83 : | { | ||
84 : | int X0, X1, X2, X3, X4, X5, X6, X7, X8; | ||
85 : | |||
86 : | edgomez | 1.6.2.1 | /* shortcut */ |
87 : | Isibaar | 1.1 | if (!((X1 = blk[4]<<11) | (X2 = blk[6]) | (X3 = blk[2]) | |
88 : | (X4 = blk[1]) | (X5 = blk[7]) | (X6 = blk[5]) | (X7 = blk[3]))) | ||
89 : | { | ||
90 : | blk[0]=blk[1]=blk[2]=blk[3]=blk[4]=blk[5]=blk[6]=blk[7]=blk[0]<<3; | ||
91 : | return; | ||
92 : | } | ||
93 : | |||
94 : | edgomez | 1.6.2.1 | X0 = (blk[0]<<11) + 128; /* for proper rounding in the fourth stage */ |
95 : | Isibaar | 1.1 | |
96 : | edgomez | 1.6.2.1 | /* first stage */ |
97 : | Isibaar | 1.1 | X8 = W7*(X4+X5); |
98 : | X4 = X8 + (W1-W7)*X4; | ||
99 : | X5 = X8 - (W1+W7)*X5; | ||
100 : | X8 = W3*(X6+X7); | ||
101 : | X6 = X8 - (W3-W5)*X6; | ||
102 : | X7 = X8 - (W3+W5)*X7; | ||
103 : | |||
104 : | edgomez | 1.6.2.1 | /* second stage */ |
105 : | Isibaar | 1.1 | X8 = X0 + X1; |
106 : | X0 -= X1; | ||
107 : | X1 = W6*(X3+X2); | ||
108 : | X2 = X1 - (W2+W6)*X2; | ||
109 : | X3 = X1 + (W2-W6)*X3; | ||
110 : | X1 = X4 + X6; | ||
111 : | X4 -= X6; | ||
112 : | X6 = X5 + X7; | ||
113 : | X5 -= X7; | ||
114 : | |||
115 : | edgomez | 1.6.2.1 | /* third stage */ |
116 : | Isibaar | 1.1 | X7 = X8 + X3; |
117 : | X8 -= X3; | ||
118 : | X3 = X0 + X2; | ||
119 : | X0 -= X2; | ||
120 : | X2 = (181*(X4+X5)+128)>>8; | ||
121 : | X4 = (181*(X4-X5)+128)>>8; | ||
122 : | |||
123 : | edgomez | 1.6.2.1 | /* fourth stage */ |
124 : | Isibaar | 1.1 | blk[0] = (X7+X1)>>8; |
125 : | blk[1] = (X3+X2)>>8; | ||
126 : | blk[2] = (X0+X4)>>8; | ||
127 : | blk[3] = (X8+X6)>>8; | ||
128 : | blk[4] = (X8-X6)>>8; | ||
129 : | blk[5] = (X0-X4)>>8; | ||
130 : | blk[6] = (X3-X2)>>8; | ||
131 : | blk[7] = (X7-X1)>>8; | ||
132 : | edgomez | 1.6.2.1 | } |
133 : | #endif | ||
134 : | Isibaar | 1.1 | |
135 : | /* column (vertical) IDCT | ||
136 : | * | ||
137 : | * 7 pi 1 | ||
138 : | * dst[8*k] = sum c[l] * src[8*l] * cos( -- * ( k + - ) * l ) | ||
139 : | * l=0 8 2 | ||
140 : | * | ||
141 : | * where: c[0] = 1/1024 | ||
142 : | * c[1..7] = (1/1024)*sqrt(2) | ||
143 : | */ | ||
144 : | edgomez | 1.6.2.1 | |
145 : | #if 0 | ||
146 : | Isibaar | 1.1 | static void idctcol(blk) |
147 : | short *blk; | ||
148 : | { | ||
149 : | int X0, X1, X2, X3, X4, X5, X6, X7, X8; | ||
150 : | |||
151 : | edgomez | 1.6.2.1 | /* shortcut */ |
152 : | Isibaar | 1.1 | if (!((X1 = (blk[8*4]<<8)) | (X2 = blk[8*6]) | (X3 = blk[8*2]) | |
153 : | (X4 = blk[8*1]) | (X5 = blk[8*7]) | (X6 = blk[8*5]) | (X7 = blk[8*3]))) | ||
154 : | { | ||
155 : | blk[8*0]=blk[8*1]=blk[8*2]=blk[8*3]=blk[8*4]=blk[8*5]=blk[8*6]=blk[8*7]= | ||
156 : | iclp[(blk[8*0]+32)>>6]; | ||
157 : | return; | ||
158 : | } | ||
159 : | |||
160 : | X0 = (blk[8*0]<<8) + 8192; | ||
161 : | |||
162 : | edgomez | 1.6.2.1 | /* first stage */ |
163 : | Isibaar | 1.1 | X8 = W7*(X4+X5) + 4; |
164 : | X4 = (X8+(W1-W7)*X4)>>3; | ||
165 : | X5 = (X8-(W1+W7)*X5)>>3; | ||
166 : | X8 = W3*(X6+X7) + 4; | ||
167 : | X6 = (X8-(W3-W5)*X6)>>3; | ||
168 : | X7 = (X8-(W3+W5)*X7)>>3; | ||
169 : | |||
170 : | edgomez | 1.6.2.1 | /* second stage */ |
171 : | Isibaar | 1.1 | X8 = X0 + X1; |
172 : | X0 -= X1; | ||
173 : | X1 = W6*(X3+X2) + 4; | ||
174 : | X2 = (X1-(W2+W6)*X2)>>3; | ||
175 : | X3 = (X1+(W2-W6)*X3)>>3; | ||
176 : | X1 = X4 + X6; | ||
177 : | X4 -= X6; | ||
178 : | X6 = X5 + X7; | ||
179 : | X5 -= X7; | ||
180 : | |||
181 : | edgomez | 1.6.2.1 | /* third stage */ |
182 : | Isibaar | 1.1 | X7 = X8 + X3; |
183 : | X8 -= X3; | ||
184 : | X3 = X0 + X2; | ||
185 : | X0 -= X2; | ||
186 : | X2 = (181*(X4+X5)+128)>>8; | ||
187 : | X4 = (181*(X4-X5)+128)>>8; | ||
188 : | |||
189 : | edgomez | 1.6.2.1 | /* fourth stage */ |
190 : | Isibaar | 1.1 | blk[8*0] = iclp[(X7+X1)>>14]; |
191 : | blk[8*1] = iclp[(X3+X2)>>14]; | ||
192 : | blk[8*2] = iclp[(X0+X4)>>14]; | ||
193 : | blk[8*3] = iclp[(X8+X6)>>14]; | ||
194 : | blk[8*4] = iclp[(X8-X6)>>14]; | ||
195 : | blk[8*5] = iclp[(X0-X4)>>14]; | ||
196 : | blk[8*6] = iclp[(X3-X2)>>14]; | ||
197 : | blk[8*7] = iclp[(X7-X1)>>14]; | ||
198 : | edgomez | 1.6.2.1 | } |
199 : | #endif | ||
200 : | Isibaar | 1.1 | |
201 : | edgomez | 1.6.2.1 | /* function pointer */ |
202 : | Isibaar | 1.1 | idctFuncPtr idct; |
203 : | |||
204 : | /* two dimensional inverse discrete cosine transform */ | ||
205 : | edgomez | 1.2 | void |
206 : | idct_int32(short *const block) | ||
207 : | Isibaar | 1.1 | { |
208 : | |||
209 : | edgomez | 1.6.2.1 | /* |
210 : | * idct_int32_init() must be called before the first call to this | ||
211 : | * function! | ||
212 : | */ | ||
213 : | |||
214 : | |||
215 : | #if 0 | ||
216 : | int i; | ||
217 : | long i; | ||
218 : | |||
219 : | for (i=0; i<8; i++) | ||
220 : | idctrow(block+8*i); | ||
221 : | |||
222 : | for (i=0; i<8; i++) | ||
223 : | idctcol(block+i); | ||
224 : | #endif | ||
225 : | Isibaar | 1.1 | |
226 : | edgomez | 1.2 | static short *blk; |
227 : | static long i; | ||
228 : | static long X0, X1, X2, X3, X4, X5, X6, X7, X8; | ||
229 : | Isibaar | 1.1 | |
230 : | |||
231 : | edgomez | 1.6.2.1 | for (i = 0; i < 8; i++) /* idct rows */ |
232 : | Isibaar | 1.1 | { |
233 : | edgomez | 1.2 | blk = block + (i << 3); |
234 : | if (! | ||
235 : | ((X1 = blk[4] << 11) | (X2 = blk[6]) | (X3 = blk[2]) | (X4 = | ||
236 : | blk[1]) | | ||
237 : | (X5 = blk[7]) | (X6 = blk[5]) | (X7 = blk[3]))) { | ||
238 : | blk[0] = blk[1] = blk[2] = blk[3] = blk[4] = blk[5] = blk[6] = | ||
239 : | blk[7] = blk[0] << 3; | ||
240 : | continue; | ||
241 : | } | ||
242 : | |||
243 : | edgomez | 1.6.2.1 | X0 = (blk[0] << 11) + 128; /* for proper rounding in the fourth stage */ |
244 : | edgomez | 1.2 | |
245 : | edgomez | 1.6.2.1 | /* first stage */ |
246 : | edgomez | 1.2 | X8 = W7 * (X4 + X5); |
247 : | X4 = X8 + (W1 - W7) * X4; | ||
248 : | X5 = X8 - (W1 + W7) * X5; | ||
249 : | X8 = W3 * (X6 + X7); | ||
250 : | X6 = X8 - (W3 - W5) * X6; | ||
251 : | X7 = X8 - (W3 + W5) * X7; | ||
252 : | |||
253 : | edgomez | 1.6.2.1 | /* second stage */ |
254 : | edgomez | 1.2 | X8 = X0 + X1; |
255 : | X0 -= X1; | ||
256 : | X1 = W6 * (X3 + X2); | ||
257 : | X2 = X1 - (W2 + W6) * X2; | ||
258 : | X3 = X1 + (W2 - W6) * X3; | ||
259 : | X1 = X4 + X6; | ||
260 : | X4 -= X6; | ||
261 : | X6 = X5 + X7; | ||
262 : | X5 -= X7; | ||
263 : | |||
264 : | edgomez | 1.6.2.1 | /* third stage */ |
265 : | edgomez | 1.2 | X7 = X8 + X3; |
266 : | X8 -= X3; | ||
267 : | X3 = X0 + X2; | ||
268 : | X0 -= X2; | ||
269 : | X2 = (181 * (X4 + X5) + 128) >> 8; | ||
270 : | X4 = (181 * (X4 - X5) + 128) >> 8; | ||
271 : | |||
272 : | edgomez | 1.6.2.1 | /* fourth stage */ |
273 : | edgomez | 1.2 | |
274 : | blk[0] = (short) ((X7 + X1) >> 8); | ||
275 : | blk[1] = (short) ((X3 + X2) >> 8); | ||
276 : | blk[2] = (short) ((X0 + X4) >> 8); | ||
277 : | blk[3] = (short) ((X8 + X6) >> 8); | ||
278 : | blk[4] = (short) ((X8 - X6) >> 8); | ||
279 : | blk[5] = (short) ((X0 - X4) >> 8); | ||
280 : | blk[6] = (short) ((X3 - X2) >> 8); | ||
281 : | blk[7] = (short) ((X7 - X1) >> 8); | ||
282 : | Isibaar | 1.1 | |
283 : | edgomez | 1.6.2.1 | } /* end for ( i = 0; i < 8; ++i ) IDCT-rows */ |
284 : | Isibaar | 1.1 | |
285 : | |||
286 : | |||
287 : | edgomez | 1.6.2.1 | for (i = 0; i < 8; i++) /* idct columns */ |
288 : | Isibaar | 1.1 | { |
289 : | edgomez | 1.2 | blk = block + i; |
290 : | edgomez | 1.6.2.1 | /* shortcut */ |
291 : | edgomez | 1.2 | if (! |
292 : | ((X1 = (blk[8 * 4] << 8)) | (X2 = blk[8 * 6]) | (X3 = | ||
293 : | blk[8 * | ||
294 : | 2]) | (X4 = | ||
295 : | blk[8 * | ||
296 : | 1]) | ||
297 : | | (X5 = blk[8 * 7]) | (X6 = blk[8 * 5]) | (X7 = blk[8 * 3]))) { | ||
298 : | blk[8 * 0] = blk[8 * 1] = blk[8 * 2] = blk[8 * 3] = blk[8 * 4] = | ||
299 : | blk[8 * 5] = blk[8 * 6] = blk[8 * 7] = | ||
300 : | iclp[(blk[8 * 0] + 32) >> 6]; | ||
301 : | continue; | ||
302 : | } | ||
303 : | |||
304 : | X0 = (blk[8 * 0] << 8) + 8192; | ||
305 : | |||
306 : | edgomez | 1.6.2.1 | /* first stage */ |
307 : | edgomez | 1.2 | X8 = W7 * (X4 + X5) + 4; |
308 : | X4 = (X8 + (W1 - W7) * X4) >> 3; | ||
309 : | X5 = (X8 - (W1 + W7) * X5) >> 3; | ||
310 : | X8 = W3 * (X6 + X7) + 4; | ||
311 : | X6 = (X8 - (W3 - W5) * X6) >> 3; | ||
312 : | X7 = (X8 - (W3 + W5) * X7) >> 3; | ||
313 : | |||
314 : | edgomez | 1.6.2.1 | /* second stage */ |
315 : | edgomez | 1.2 | X8 = X0 + X1; |
316 : | X0 -= X1; | ||
317 : | X1 = W6 * (X3 + X2) + 4; | ||
318 : | X2 = (X1 - (W2 + W6) * X2) >> 3; | ||
319 : | X3 = (X1 + (W2 - W6) * X3) >> 3; | ||
320 : | X1 = X4 + X6; | ||
321 : | X4 -= X6; | ||
322 : | X6 = X5 + X7; | ||
323 : | X5 -= X7; | ||
324 : | |||
325 : | edgomez | 1.6.2.1 | /* third stage */ |
326 : | edgomez | 1.2 | X7 = X8 + X3; |
327 : | X8 -= X3; | ||
328 : | X3 = X0 + X2; | ||
329 : | X0 -= X2; | ||
330 : | X2 = (181 * (X4 + X5) + 128) >> 8; | ||
331 : | X4 = (181 * (X4 - X5) + 128) >> 8; | ||
332 : | |||
333 : | edgomez | 1.6.2.1 | /* fourth stage */ |
334 : | edgomez | 1.2 | blk[8 * 0] = iclp[(X7 + X1) >> 14]; |
335 : | blk[8 * 1] = iclp[(X3 + X2) >> 14]; | ||
336 : | blk[8 * 2] = iclp[(X0 + X4) >> 14]; | ||
337 : | blk[8 * 3] = iclp[(X8 + X6) >> 14]; | ||
338 : | blk[8 * 4] = iclp[(X8 - X6) >> 14]; | ||
339 : | blk[8 * 5] = iclp[(X0 - X4) >> 14]; | ||
340 : | blk[8 * 6] = iclp[(X3 - X2) >> 14]; | ||
341 : | blk[8 * 7] = iclp[(X7 - X1) >> 14]; | ||
342 : | Isibaar | 1.1 | } |
343 : | |||
344 : | edgomez | 1.6.2.1 | } /* end function idct_int32(block) */ |
345 : | Isibaar | 1.1 | |
346 : | |||
347 : | edgomez | 1.2 | void |
348 : | edgomez | 1.6 | idct_int32_init() |
349 : | Isibaar | 1.1 | { |
350 : | edgomez | 1.2 | int i; |
351 : | Isibaar | 1.1 | |
352 : | edgomez | 1.2 | iclp = iclip + 512; |
353 : | for (i = -512; i < 512; i++) | ||
354 : | iclp[i] = (i < -256) ? -256 : ((i > 255) ? 255 : i); | ||
355 : | Isibaar | 1.1 | } |
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