1 /*
2  * jddctmgr.c
3  *
4  * This file was part of the Independent JPEG Group's software:
5  * Copyright (C) 1994-1996, Thomas G. Lane.
6  * Modified 2002-2010 by Guido Vollbeding.
7  * libjpeg-turbo Modifications:
8  * Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB
9  * Copyright (C) 2010, 2015, D. R. Commander.
10  * Copyright (C) 2013, MIPS Technologies, Inc., California.
11  * For conditions of distribution and use, see the accompanying README.ijg
12  * file.
13  *
14  * This file contains the inverse-DCT management logic.
15  * This code selects a particular IDCT implementation to be used,
16  * and it performs related housekeeping chores.  No code in this file
17  * is executed per IDCT step, only during output pass setup.
18  *
19  * Note that the IDCT routines are responsible for performing coefficient
20  * dequantization as well as the IDCT proper.  This module sets up the
21  * dequantization multiplier table needed by the IDCT routine.
22  */
23 
24 #define JPEG_INTERNALS
25 #include "jinclude.h"
26 #include "jpeglib.h"
27 #include "jdct.h"               /* Private declarations for DCT subsystem */
28 #include "jsimddct.h"
29 #include "jpegcomp.h"
30 
31 
32 /*
33  * The decompressor input side (jdinput.c) saves away the appropriate
34  * quantization table for each component at the start of the first scan
35  * involving that component.  (This is necessary in order to correctly
36  * decode files that reuse Q-table slots.)
37  * When we are ready to make an output pass, the saved Q-table is converted
38  * to a multiplier table that will actually be used by the IDCT routine.
39  * The multiplier table contents are IDCT-method-dependent.  To support
40  * application changes in IDCT method between scans, we can remake the
41  * multiplier tables if necessary.
42  * In buffered-image mode, the first output pass may occur before any data
43  * has been seen for some components, and thus before their Q-tables have
44  * been saved away.  To handle this case, multiplier tables are preset
45  * to zeroes; the result of the IDCT will be a neutral gray level.
46  */
47 
48 
49 /* Private subobject for this module */
50 
51 typedef struct {
52   struct jpeg_inverse_dct pub;  /* public fields */
53 
54   /* This array contains the IDCT method code that each multiplier table
55    * is currently set up for, or -1 if it's not yet set up.
56    * The actual multiplier tables are pointed to by dct_table in the
57    * per-component comp_info structures.
58    */
59   int cur_method[MAX_COMPONENTS];
60 } my_idct_controller;
61 
62 typedef my_idct_controller *my_idct_ptr;
63 
64 
65 /* Allocated multiplier tables: big enough for any supported variant */
66 
67 typedef union {
68   ISLOW_MULT_TYPE islow_array[DCTSIZE2];
69 #ifdef DCT_IFAST_SUPPORTED
70   IFAST_MULT_TYPE ifast_array[DCTSIZE2];
71 #endif
72 #ifdef DCT_FLOAT_SUPPORTED
73   FLOAT_MULT_TYPE float_array[DCTSIZE2];
74 #endif
75 } multiplier_table;
76 
77 
78 /* The current scaled-IDCT routines require ISLOW-style multiplier tables,
79  * so be sure to compile that code if either ISLOW or SCALING is requested.
80  */
81 #ifdef DCT_ISLOW_SUPPORTED
82 #define PROVIDE_ISLOW_TABLES
83 #else
84 #ifdef IDCT_SCALING_SUPPORTED
85 #define PROVIDE_ISLOW_TABLES
86 #endif
87 #endif
88 
89 
90 /*
91  * Prepare for an output pass.
92  * Here we select the proper IDCT routine for each component and build
93  * a matching multiplier table.
94  */
95 
96 METHODDEF(void)
start_pass(j_decompress_ptr cinfo)97 start_pass (j_decompress_ptr cinfo)
98 {
99   my_idct_ptr idct = (my_idct_ptr) cinfo->idct;
100   int ci, i;
101   jpeg_component_info *compptr;
102   int method = 0;
103   inverse_DCT_method_ptr method_ptr = NULL;
104   JQUANT_TBL *qtbl;
105 
106   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
107        ci++, compptr++) {
108     /* Select the proper IDCT routine for this component's scaling */
109     switch (compptr->_DCT_scaled_size) {
110 #ifdef IDCT_SCALING_SUPPORTED
111     case 1:
112       method_ptr = jpeg_idct_1x1;
113       method = JDCT_ISLOW;      /* jidctred uses islow-style table */
114       break;
115     case 2:
116       if (jsimd_can_idct_2x2())
117         method_ptr = jsimd_idct_2x2;
118       else
119         method_ptr = jpeg_idct_2x2;
120       method = JDCT_ISLOW;      /* jidctred uses islow-style table */
121       break;
122     case 3:
123       method_ptr = jpeg_idct_3x3;
124       method = JDCT_ISLOW;      /* jidctint uses islow-style table */
125       break;
126     case 4:
127       if (jsimd_can_idct_4x4())
128         method_ptr = jsimd_idct_4x4;
129       else
130         method_ptr = jpeg_idct_4x4;
131       method = JDCT_ISLOW;      /* jidctred uses islow-style table */
132       break;
133     case 5:
134       method_ptr = jpeg_idct_5x5;
135       method = JDCT_ISLOW;      /* jidctint uses islow-style table */
136       break;
137     case 6:
138 #if defined(__mips__)
139       if (jsimd_can_idct_6x6())
140         method_ptr = jsimd_idct_6x6;
141       else
142 #endif
143       method_ptr = jpeg_idct_6x6;
144       method = JDCT_ISLOW;      /* jidctint uses islow-style table */
145       break;
146     case 7:
147       method_ptr = jpeg_idct_7x7;
148       method = JDCT_ISLOW;      /* jidctint uses islow-style table */
149       break;
150 #endif
151     case DCTSIZE:
152       switch (cinfo->dct_method) {
153 #ifdef DCT_ISLOW_SUPPORTED
154       case JDCT_ISLOW:
155         if (jsimd_can_idct_islow())
156           method_ptr = jsimd_idct_islow;
157         else
158           method_ptr = jpeg_idct_islow;
159         method = JDCT_ISLOW;
160         break;
161 #endif
162 #ifdef DCT_IFAST_SUPPORTED
163       case JDCT_IFAST:
164         if (jsimd_can_idct_ifast())
165           method_ptr = jsimd_idct_ifast;
166         else
167           method_ptr = jpeg_idct_ifast;
168         method = JDCT_IFAST;
169         break;
170 #endif
171 #ifdef DCT_FLOAT_SUPPORTED
172       case JDCT_FLOAT:
173         if (jsimd_can_idct_float())
174           method_ptr = jsimd_idct_float;
175         else
176           method_ptr = jpeg_idct_float;
177         method = JDCT_FLOAT;
178         break;
179 #endif
180       default:
181         ERREXIT(cinfo, JERR_NOT_COMPILED);
182         break;
183       }
184       break;
185 #ifdef IDCT_SCALING_SUPPORTED
186     case 9:
187       method_ptr = jpeg_idct_9x9;
188       method = JDCT_ISLOW;      /* jidctint uses islow-style table */
189       break;
190     case 10:
191       method_ptr = jpeg_idct_10x10;
192       method = JDCT_ISLOW;      /* jidctint uses islow-style table */
193       break;
194     case 11:
195       method_ptr = jpeg_idct_11x11;
196       method = JDCT_ISLOW;      /* jidctint uses islow-style table */
197       break;
198     case 12:
199 #if defined(__mips__)
200       if (jsimd_can_idct_12x12())
201         method_ptr = jsimd_idct_12x12;
202       else
203 #endif
204       method_ptr = jpeg_idct_12x12;
205       method = JDCT_ISLOW;      /* jidctint uses islow-style table */
206       break;
207     case 13:
208       method_ptr = jpeg_idct_13x13;
209       method = JDCT_ISLOW;      /* jidctint uses islow-style table */
210       break;
211     case 14:
212       method_ptr = jpeg_idct_14x14;
213       method = JDCT_ISLOW;      /* jidctint uses islow-style table */
214       break;
215     case 15:
216       method_ptr = jpeg_idct_15x15;
217       method = JDCT_ISLOW;      /* jidctint uses islow-style table */
218       break;
219     case 16:
220       method_ptr = jpeg_idct_16x16;
221       method = JDCT_ISLOW;      /* jidctint uses islow-style table */
222       break;
223 #endif
224     default:
225       ERREXIT1(cinfo, JERR_BAD_DCTSIZE, compptr->_DCT_scaled_size);
226       break;
227     }
228     idct->pub.inverse_DCT[ci] = method_ptr;
229     /* Create multiplier table from quant table.
230      * However, we can skip this if the component is uninteresting
231      * or if we already built the table.  Also, if no quant table
232      * has yet been saved for the component, we leave the
233      * multiplier table all-zero; we'll be reading zeroes from the
234      * coefficient controller's buffer anyway.
235      */
236     if (! compptr->component_needed || idct->cur_method[ci] == method)
237       continue;
238     qtbl = compptr->quant_table;
239     if (qtbl == NULL)           /* happens if no data yet for component */
240       continue;
241     idct->cur_method[ci] = method;
242     switch (method) {
243 #ifdef PROVIDE_ISLOW_TABLES
244     case JDCT_ISLOW:
245       {
246         /* For LL&M IDCT method, multipliers are equal to raw quantization
247          * coefficients, but are stored as ints to ensure access efficiency.
248          */
249         ISLOW_MULT_TYPE *ismtbl = (ISLOW_MULT_TYPE *) compptr->dct_table;
250         for (i = 0; i < DCTSIZE2; i++) {
251           ismtbl[i] = (ISLOW_MULT_TYPE) qtbl->quantval[i];
252         }
253       }
254       break;
255 #endif
256 #ifdef DCT_IFAST_SUPPORTED
257     case JDCT_IFAST:
258       {
259         /* For AA&N IDCT method, multipliers are equal to quantization
260          * coefficients scaled by scalefactor[row]*scalefactor[col], where
261          *   scalefactor[0] = 1
262          *   scalefactor[k] = cos(k*PI/16) * sqrt(2)    for k=1..7
263          * For integer operation, the multiplier table is to be scaled by
264          * IFAST_SCALE_BITS.
265          */
266         IFAST_MULT_TYPE *ifmtbl = (IFAST_MULT_TYPE *) compptr->dct_table;
267 #define CONST_BITS 14
268         static const INT16 aanscales[DCTSIZE2] = {
269           /* precomputed values scaled up by 14 bits */
270           16384, 22725, 21407, 19266, 16384, 12873,  8867,  4520,
271           22725, 31521, 29692, 26722, 22725, 17855, 12299,  6270,
272           21407, 29692, 27969, 25172, 21407, 16819, 11585,  5906,
273           19266, 26722, 25172, 22654, 19266, 15137, 10426,  5315,
274           16384, 22725, 21407, 19266, 16384, 12873,  8867,  4520,
275           12873, 17855, 16819, 15137, 12873, 10114,  6967,  3552,
276            8867, 12299, 11585, 10426,  8867,  6967,  4799,  2446,
277            4520,  6270,  5906,  5315,  4520,  3552,  2446,  1247
278         };
279         SHIFT_TEMPS
280 
281         for (i = 0; i < DCTSIZE2; i++) {
282           ifmtbl[i] = (IFAST_MULT_TYPE)
283             DESCALE(MULTIPLY16V16((JLONG) qtbl->quantval[i],
284                                   (JLONG) aanscales[i]),
285                     CONST_BITS-IFAST_SCALE_BITS);
286         }
287       }
288       break;
289 #endif
290 #ifdef DCT_FLOAT_SUPPORTED
291     case JDCT_FLOAT:
292       {
293         /* For float AA&N IDCT method, multipliers are equal to quantization
294          * coefficients scaled by scalefactor[row]*scalefactor[col], where
295          *   scalefactor[0] = 1
296          *   scalefactor[k] = cos(k*PI/16) * sqrt(2)    for k=1..7
297          */
298         FLOAT_MULT_TYPE *fmtbl = (FLOAT_MULT_TYPE *) compptr->dct_table;
299         int row, col;
300         static const double aanscalefactor[DCTSIZE] = {
301           1.0, 1.387039845, 1.306562965, 1.175875602,
302           1.0, 0.785694958, 0.541196100, 0.275899379
303         };
304 
305         i = 0;
306         for (row = 0; row < DCTSIZE; row++) {
307           for (col = 0; col < DCTSIZE; col++) {
308             fmtbl[i] = (FLOAT_MULT_TYPE)
309               ((double) qtbl->quantval[i] *
310                aanscalefactor[row] * aanscalefactor[col]);
311             i++;
312           }
313         }
314       }
315       break;
316 #endif
317     default:
318       ERREXIT(cinfo, JERR_NOT_COMPILED);
319       break;
320     }
321   }
322 }
323 
324 
325 /*
326  * Initialize IDCT manager.
327  */
328 
329 GLOBAL(void)
jinit_inverse_dct(j_decompress_ptr cinfo)330 jinit_inverse_dct (j_decompress_ptr cinfo)
331 {
332   my_idct_ptr idct;
333   int ci;
334   jpeg_component_info *compptr;
335 
336   idct = (my_idct_ptr)
337     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
338                                 sizeof(my_idct_controller));
339   cinfo->idct = (struct jpeg_inverse_dct *) idct;
340   idct->pub.start_pass = start_pass;
341 
342   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
343        ci++, compptr++) {
344     /* Allocate and pre-zero a multiplier table for each component */
345     compptr->dct_table =
346       (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
347                                   sizeof(multiplier_table));
348     MEMZERO(compptr->dct_table, sizeof(multiplier_table));
349     /* Mark multiplier table not yet set up for any method */
350     idct->cur_method[ci] = -1;
351   }
352 }
353