COSMOS core  1.0.2 (beta)
Comprehensive Open-architecture Solution for Mission Operations Systems
Macros | Functions
jidctint.cpp File Reference
#include "jinclude.h"
#include "jpeglib.h"
#include "jdct.h"
Include dependency graph for jidctint.cpp:

Macros

#define JPEG_INTERNALS
 
#define CONST_BITS   13
 
#define PASS1_BITS   2
 
#define FIX_0_298631336   ((int32_t) 2446) /* FIX(0.298631336) */
 
#define FIX_0_390180644   ((int32_t) 3196) /* FIX(0.390180644) */
 
#define FIX_0_541196100   ((int32_t) 4433) /* FIX(0.541196100) */
 
#define FIX_0_765366865   ((int32_t) 6270) /* FIX(0.765366865) */
 
#define FIX_0_899976223   ((int32_t) 7373) /* FIX(0.899976223) */
 
#define FIX_1_175875602   ((int32_t) 9633) /* FIX(1.175875602) */
 
#define FIX_1_501321110   ((int32_t) 12299) /* FIX(1.501321110) */
 
#define FIX_1_847759065   ((int32_t) 15137) /* FIX(1.847759065) */
 
#define FIX_1_961570560   ((int32_t) 16069) /* FIX(1.961570560) */
 
#define FIX_2_053119869   ((int32_t) 16819) /* FIX(2.053119869) */
 
#define FIX_2_562915447   ((int32_t) 20995) /* FIX(2.562915447) */
 
#define FIX_3_072711026   ((int32_t) 25172) /* FIX(3.072711026) */
 
#define MULTIPLY(var, const)   MULTIPLY16C16(var,const)
 
#define DEQUANTIZE(coef, quantval)   (((ISLOW_MULT_TYPE) (coef)) * (quantval))
 

Functions

void jpeg_idct_islow (j_decompress_ptr cinfo, jpeg_component_info *compptr, JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)
 

Macro Definition Documentation

#define JPEG_INTERNALS
#define CONST_BITS   13
#define PASS1_BITS   2
#define FIX_0_298631336   ((int32_t) 2446) /* FIX(0.298631336) */
#define FIX_0_390180644   ((int32_t) 3196) /* FIX(0.390180644) */
#define FIX_0_541196100   ((int32_t) 4433) /* FIX(0.541196100) */
#define FIX_0_765366865   ((int32_t) 6270) /* FIX(0.765366865) */
#define FIX_0_899976223   ((int32_t) 7373) /* FIX(0.899976223) */
#define FIX_1_175875602   ((int32_t) 9633) /* FIX(1.175875602) */
#define FIX_1_501321110   ((int32_t) 12299) /* FIX(1.501321110) */
#define FIX_1_847759065   ((int32_t) 15137) /* FIX(1.847759065) */
#define FIX_1_961570560   ((int32_t) 16069) /* FIX(1.961570560) */
#define FIX_2_053119869   ((int32_t) 16819) /* FIX(2.053119869) */
#define FIX_2_562915447   ((int32_t) 20995) /* FIX(2.562915447) */
#define FIX_3_072711026   ((int32_t) 25172) /* FIX(3.072711026) */
#define MULTIPLY (   var,
  const 
)    MULTIPLY16C16(var,const)
#define DEQUANTIZE (   coef,
  quantval 
)    (((ISLOW_MULT_TYPE) (coef)) * (quantval))

Function Documentation

void jpeg_idct_islow ( j_decompress_ptr  cinfo,
jpeg_component_info *  compptr,
JCOEFPTR  coef_block,
JSAMPARRAY  output_buf,
JDIMENSION  output_col 
)
151 {
152  int32_t tmp0, tmp1, tmp2, tmp3;
153  int32_t tmp10, tmp11, tmp12, tmp13;
154  int32_t z1, z2, z3, z4, z5;
155  JCOEFPTR inptr;
156  ISLOW_MULT_TYPE * quantptr;
157  int * wsptr;
158  JSAMPROW outptr;
159  JSAMPLE *range_limit = IDCT_range_limit(cinfo);
160  int ctr;
161  int workspace[DCTSIZE2]; /* buffers data between passes */
162  SHIFT_TEMPS
163 
164  /* Pass 1: process columns from input, store into work array. */
165  /* Note results are scaled up by sqrt(8) compared to a true IDCT; */
166  /* furthermore, we scale the results by 2**PASS1_BITS. */
167 
168  inptr = coef_block;
169  quantptr = (ISLOW_MULT_TYPE *) compptr->dct_table;
170  wsptr = workspace;
171  for (ctr = DCTSIZE; ctr > 0; ctr--) {
172  /* Due to quantization, we will usually find that many of the input
173  * coefficients are zero, especially the AC terms. We can exploit this
174  * by short-circuiting the IDCT calculation for any column in which all
175  * the AC terms are zero. In that case each output is equal to the
176  * DC coefficient (with scale factor as needed).
177  * With typical images and quantization tables, half or more of the
178  * column DCT calculations can be simplified this way.
179  */
180 
181  if (inptr[DCTSIZE*1] == 0 && inptr[DCTSIZE*2] == 0 &&
182  inptr[DCTSIZE*3] == 0 && inptr[DCTSIZE*4] == 0 &&
183  inptr[DCTSIZE*5] == 0 && inptr[DCTSIZE*6] == 0 &&
184  inptr[DCTSIZE*7] == 0) {
185  /* AC terms all zero */
186  int dcval = DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]) << PASS1_BITS;
187 
188  wsptr[DCTSIZE*0] = dcval;
189  wsptr[DCTSIZE*1] = dcval;
190  wsptr[DCTSIZE*2] = dcval;
191  wsptr[DCTSIZE*3] = dcval;
192  wsptr[DCTSIZE*4] = dcval;
193  wsptr[DCTSIZE*5] = dcval;
194  wsptr[DCTSIZE*6] = dcval;
195  wsptr[DCTSIZE*7] = dcval;
196 
197  inptr++; /* advance pointers to next column */
198  quantptr++;
199  wsptr++;
200  continue;
201  }
202 
203  /* Even part: reverse the even part of the forward DCT. */
204  /* The rotator is sqrt(2)*c(-6). */
205 
206  z2 = DEQUANTIZE(inptr[DCTSIZE*2], quantptr[DCTSIZE*2]);
207  z3 = DEQUANTIZE(inptr[DCTSIZE*6], quantptr[DCTSIZE*6]);
208 
209  z1 = MULTIPLY(z2 + z3, FIX_0_541196100);
210  tmp2 = z1 + MULTIPLY(z3, - FIX_1_847759065);
211  tmp3 = z1 + MULTIPLY(z2, FIX_0_765366865);
212 
213  z2 = DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]);
214  z3 = DEQUANTIZE(inptr[DCTSIZE*4], quantptr[DCTSIZE*4]);
215 
216  tmp0 = (z2 + z3) << CONST_BITS;
217  tmp1 = (z2 - z3) << CONST_BITS;
218 
219  tmp10 = tmp0 + tmp3;
220  tmp13 = tmp0 - tmp3;
221  tmp11 = tmp1 + tmp2;
222  tmp12 = tmp1 - tmp2;
223 
224  /* Odd part per figure 8; the matrix is unitary and hence its
225  * transpose is its inverse. i0..i3 are y7,y5,y3,y1 respectively.
226  */
227 
228  tmp0 = DEQUANTIZE(inptr[DCTSIZE*7], quantptr[DCTSIZE*7]);
229  tmp1 = DEQUANTIZE(inptr[DCTSIZE*5], quantptr[DCTSIZE*5]);
230  tmp2 = DEQUANTIZE(inptr[DCTSIZE*3], quantptr[DCTSIZE*3]);
231  tmp3 = DEQUANTIZE(inptr[DCTSIZE*1], quantptr[DCTSIZE*1]);
232 
233  z1 = tmp0 + tmp3;
234  z2 = tmp1 + tmp2;
235  z3 = tmp0 + tmp2;
236  z4 = tmp1 + tmp3;
237  z5 = MULTIPLY(z3 + z4, FIX_1_175875602); /* sqrt(2) * c3 */
238 
239  tmp0 = MULTIPLY(tmp0, FIX_0_298631336); /* sqrt(2) * (-c1+c3+c5-c7) */
240  tmp1 = MULTIPLY(tmp1, FIX_2_053119869); /* sqrt(2) * ( c1+c3-c5+c7) */
241  tmp2 = MULTIPLY(tmp2, FIX_3_072711026); /* sqrt(2) * ( c1+c3+c5-c7) */
242  tmp3 = MULTIPLY(tmp3, FIX_1_501321110); /* sqrt(2) * ( c1+c3-c5-c7) */
243  z1 = MULTIPLY(z1, - FIX_0_899976223); /* sqrt(2) * (c7-c3) */
244  z2 = MULTIPLY(z2, - FIX_2_562915447); /* sqrt(2) * (-c1-c3) */
245  z3 = MULTIPLY(z3, - FIX_1_961570560); /* sqrt(2) * (-c3-c5) */
246  z4 = MULTIPLY(z4, - FIX_0_390180644); /* sqrt(2) * (c5-c3) */
247 
248  z3 += z5;
249  z4 += z5;
250 
251  tmp0 += z1 + z3;
252  tmp1 += z2 + z4;
253  tmp2 += z2 + z3;
254  tmp3 += z1 + z4;
255 
256  /* Final output stage: inputs are tmp10..tmp13, tmp0..tmp3 */
257 
258  wsptr[DCTSIZE*0] = (int) DESCALE(tmp10 + tmp3, CONST_BITS-PASS1_BITS);
259  wsptr[DCTSIZE*7] = (int) DESCALE(tmp10 - tmp3, CONST_BITS-PASS1_BITS);
260  wsptr[DCTSIZE*1] = (int) DESCALE(tmp11 + tmp2, CONST_BITS-PASS1_BITS);
261  wsptr[DCTSIZE*6] = (int) DESCALE(tmp11 - tmp2, CONST_BITS-PASS1_BITS);
262  wsptr[DCTSIZE*2] = (int) DESCALE(tmp12 + tmp1, CONST_BITS-PASS1_BITS);
263  wsptr[DCTSIZE*5] = (int) DESCALE(tmp12 - tmp1, CONST_BITS-PASS1_BITS);
264  wsptr[DCTSIZE*3] = (int) DESCALE(tmp13 + tmp0, CONST_BITS-PASS1_BITS);
265  wsptr[DCTSIZE*4] = (int) DESCALE(tmp13 - tmp0, CONST_BITS-PASS1_BITS);
266 
267  inptr++; /* advance pointers to next column */
268  quantptr++;
269  wsptr++;
270  }
271 
272  /* Pass 2: process rows from work array, store into output array. */
273  /* Note that we must descale the results by a factor of 8 == 2**3, */
274  /* and also undo the PASS1_BITS scaling. */
275 
276  wsptr = workspace;
277  for (ctr = 0; ctr < DCTSIZE; ctr++) {
278  outptr = output_buf[ctr] + output_col;
279  /* Rows of zeroes can be exploited in the same way as we did with columns.
280  * However, the column calculation has created many nonzero AC terms, so
281  * the simplification applies less often (typically 5% to 10% of the time).
282  * On machines with very fast multiplication, it's possible that the
283  * test takes more time than it's worth. In that case this section
284  * may be commented out.
285  */
286 
287 #ifndef NO_ZERO_ROW_TEST
288  if (wsptr[1] == 0 && wsptr[2] == 0 && wsptr[3] == 0 && wsptr[4] == 0 &&
289  wsptr[5] == 0 && wsptr[6] == 0 && wsptr[7] == 0) {
290  /* AC terms all zero */
291  JSAMPLE dcval = range_limit[(int) DESCALE((int32_t) wsptr[0], PASS1_BITS+3)
292  & RANGE_MASK];
293 
294  outptr[0] = dcval;
295  outptr[1] = dcval;
296  outptr[2] = dcval;
297  outptr[3] = dcval;
298  outptr[4] = dcval;
299  outptr[5] = dcval;
300  outptr[6] = dcval;
301  outptr[7] = dcval;
302 
303  wsptr += DCTSIZE; /* advance pointer to next row */
304  continue;
305  }
306 #endif
307 
308  /* Even part: reverse the even part of the forward DCT. */
309  /* The rotator is sqrt(2)*c(-6). */
310 
311  z2 = (int32_t) wsptr[2];
312  z3 = (int32_t) wsptr[6];
313 
314  z1 = MULTIPLY(z2 + z3, FIX_0_541196100);
315  tmp2 = z1 + MULTIPLY(z3, - FIX_1_847759065);
316  tmp3 = z1 + MULTIPLY(z2, FIX_0_765366865);
317 
318  tmp0 = ((int32_t) wsptr[0] + (int32_t) wsptr[4]) << CONST_BITS;
319  tmp1 = ((int32_t) wsptr[0] - (int32_t) wsptr[4]) << CONST_BITS;
320 
321  tmp10 = tmp0 + tmp3;
322  tmp13 = tmp0 - tmp3;
323  tmp11 = tmp1 + tmp2;
324  tmp12 = tmp1 - tmp2;
325 
326  /* Odd part per figure 8; the matrix is unitary and hence its
327  * transpose is its inverse. i0..i3 are y7,y5,y3,y1 respectively.
328  */
329 
330  tmp0 = (int32_t) wsptr[7];
331  tmp1 = (int32_t) wsptr[5];
332  tmp2 = (int32_t) wsptr[3];
333  tmp3 = (int32_t) wsptr[1];
334 
335  z1 = tmp0 + tmp3;
336  z2 = tmp1 + tmp2;
337  z3 = tmp0 + tmp2;
338  z4 = tmp1 + tmp3;
339  z5 = MULTIPLY(z3 + z4, FIX_1_175875602); /* sqrt(2) * c3 */
340 
341  tmp0 = MULTIPLY(tmp0, FIX_0_298631336); /* sqrt(2) * (-c1+c3+c5-c7) */
342  tmp1 = MULTIPLY(tmp1, FIX_2_053119869); /* sqrt(2) * ( c1+c3-c5+c7) */
343  tmp2 = MULTIPLY(tmp2, FIX_3_072711026); /* sqrt(2) * ( c1+c3+c5-c7) */
344  tmp3 = MULTIPLY(tmp3, FIX_1_501321110); /* sqrt(2) * ( c1+c3-c5-c7) */
345  z1 = MULTIPLY(z1, - FIX_0_899976223); /* sqrt(2) * (c7-c3) */
346  z2 = MULTIPLY(z2, - FIX_2_562915447); /* sqrt(2) * (-c1-c3) */
347  z3 = MULTIPLY(z3, - FIX_1_961570560); /* sqrt(2) * (-c3-c5) */
348  z4 = MULTIPLY(z4, - FIX_0_390180644); /* sqrt(2) * (c5-c3) */
349 
350  z3 += z5;
351  z4 += z5;
352 
353  tmp0 += z1 + z3;
354  tmp1 += z2 + z4;
355  tmp2 += z2 + z3;
356  tmp3 += z1 + z4;
357 
358  /* Final output stage: inputs are tmp10..tmp13, tmp0..tmp3 */
359 
360  outptr[0] = range_limit[(int) DESCALE(tmp10 + tmp3,
361  CONST_BITS+PASS1_BITS+3)
362  & RANGE_MASK];
363  outptr[7] = range_limit[(int) DESCALE(tmp10 - tmp3,
364  CONST_BITS+PASS1_BITS+3)
365  & RANGE_MASK];
366  outptr[1] = range_limit[(int) DESCALE(tmp11 + tmp2,
367  CONST_BITS+PASS1_BITS+3)
368  & RANGE_MASK];
369  outptr[6] = range_limit[(int) DESCALE(tmp11 - tmp2,
370  CONST_BITS+PASS1_BITS+3)
371  & RANGE_MASK];
372  outptr[2] = range_limit[(int) DESCALE(tmp12 + tmp1,
373  CONST_BITS+PASS1_BITS+3)
374  & RANGE_MASK];
375  outptr[5] = range_limit[(int) DESCALE(tmp12 - tmp1,
376  CONST_BITS+PASS1_BITS+3)
377  & RANGE_MASK];
378  outptr[3] = range_limit[(int) DESCALE(tmp13 + tmp0,
379  CONST_BITS+PASS1_BITS+3)
380  & RANGE_MASK];
381  outptr[4] = range_limit[(int) DESCALE(tmp13 - tmp0,
382  CONST_BITS+PASS1_BITS+3)
383  & RANGE_MASK];
384 
385  wsptr += DCTSIZE; /* advance pointer to next row */
386  }
387 }
DESCALE
#define DESCALE(x, n)
Definition: jdct.h:146
FIX_0_298631336
#define FIX_0_298631336
Definition: jidctint.cpp:93
IDCT_range_limit
#define IDCT_range_limit(cinfo)
Definition: jdct.h:76
JSAMPLE
char JSAMPLE
Definition: jmorecfg.h:64
FIX_0_541196100
#define FIX_0_541196100
Definition: jidctint.cpp:95
FIX_3_072711026
#define FIX_3_072711026
Definition: jidctint.cpp:104
coef_block
jpeg_component_info JCOEFPTR coef_block
Definition: jdct.h:102
jpeg_component_info::dct_table
void * dct_table
Definition: jpeglib.h:183
RANGE_MASK
#define RANGE_MASK
Definition: jdct.h:78
SHIFT_TEMPS
#define SHIFT_TEMPS
Definition: jpegint.h:289
JSAMPROW
JSAMPLE * JSAMPROW
Definition: jpeglib.h:71
DEQUANTIZE
#define DEQUANTIZE(coef, quantval)
Definition: jidctint.cpp:140
output_col
jpeg_component_info JCOEFPTR JSAMPARRAY JDIMENSION output_col
Definition: jdct.h:102
CONST_BITS
#define CONST_BITS
Definition: jidctint.cpp:78
FIX_2_053119869
#define FIX_2_053119869
Definition: jidctint.cpp:102
FIX_0_390180644
#define FIX_0_390180644
Definition: jidctint.cpp:94
DCTSIZE2
#define DCTSIZE2
Definition: jpeglib.h:47
MULTIPLY
#define MULTIPLY(var, const)
Definition: jidctint.cpp:129
ISLOW_MULT_TYPE
MULTIPLIER ISLOW_MULT_TYPE
Definition: jdct.h:56
PASS1_BITS
#define PASS1_BITS
Definition: jidctint.cpp:79
JCOEFPTR
JCOEF * JCOEFPTR
Definition: jpeglib.h:80
FIX_1_847759065
#define FIX_1_847759065
Definition: jidctint.cpp:100
FIX_1_501321110
#define FIX_1_501321110
Definition: jidctint.cpp:99
DCTSIZE
#define DCTSIZE
Definition: jpeglib.h:46
FIX_1_961570560
#define FIX_1_961570560
Definition: jidctint.cpp:101
output_buf
jpeg_component_info JCOEFPTR JSAMPARRAY output_buf
Definition: jdct.h:102
FIX_1_175875602
#define FIX_1_175875602
Definition: jidctint.cpp:98
FIX_2_562915447
#define FIX_2_562915447
Definition: jidctint.cpp:103
FIX_0_899976223
#define FIX_0_899976223
Definition: jidctint.cpp:97
FIX_0_765366865
#define FIX_0_765366865
Definition: jidctint.cpp:96