1/*
2 * jdct.h
3 *
4 * Copyright (C) 1994-1996, Thomas G. Lane.
5 * This file is part of the Independent JPEG Group's software.
6 * For conditions of distribution and use, see the accompanying README file.
7 *
8 * This include file contains common declarations for the forward and
9 * inverse DCT modules. These declarations are private to the DCT managers
10 * (jcdctmgr.c, jddctmgr.c) and the individual DCT algorithms.
11 * The individual DCT algorithms are kept in separate files to ease
12 * machine-dependent tuning (e.g., assembly coding).
13 */
14
15
16/*
17 * A forward DCT routine is given a pointer to an input sample array and
18 * a pointer to a work area of type DCTELEM[]; the DCT is to be performed
19 * in-place in that buffer. Type DCTELEM is int for 8-bit samples, INT32
20 * for 12-bit samples. (NOTE: Floating-point DCT implementations use an
21 * array of type FAST_FLOAT, instead.)
22 * The input data is to be fetched from the sample array starting at a
23 * specified column. (Any row offset needed will be applied to the array
24 * pointer before it is passed to the FDCT code.)
25 * Note that the number of samples fetched by the FDCT routine is
26 * DCT_h_scaled_size * DCT_v_scaled_size.
27 * The DCT outputs are returned scaled up by a factor of 8; they therefore
28 * have a range of +-8K for 8-bit data, +-128K for 12-bit data. This
29 * convention improves accuracy in integer implementations and saves some
30 * work in floating-point ones.
31 * Quantization of the output coefficients is done by jcdctmgr.c.
32 */
33
34#if BITS_IN_JSAMPLE == 8
35typedef int DCTELEM; /* 16 or 32 bits is fine */
36#else
37typedef INT32 DCTELEM; /* must have 32 bits */
38#endif
39
40typedef JMETHOD(void, forward_DCT_method_ptr, (DCTELEM * data,
41 JSAMPARRAY sample_data,
42 JDIMENSION start_col));
43typedef JMETHOD(void, float_DCT_method_ptr, (FAST_FLOAT * data,
44 JSAMPARRAY sample_data,
45 JDIMENSION start_col));
46
47
48/*
49 * An inverse DCT routine is given a pointer to the input JBLOCK and a pointer
50 * to an output sample array. The routine must dequantize the input data as
51 * well as perform the IDCT; for dequantization, it uses the multiplier table
52 * pointed to by compptr->dct_table. The output data is to be placed into the
53 * sample array starting at a specified column. (Any row offset needed will
54 * be applied to the array pointer before it is passed to the IDCT code.)
55 * Note that the number of samples emitted by the IDCT routine is
56 * DCT_h_scaled_size * DCT_v_scaled_size.
57 */
58
59/* typedef inverse_DCT_method_ptr is declared in jpegint.h */
60
61/*
62 * Each IDCT routine has its own ideas about the best dct_table element type.
63 */
64
65typedef MULTIPLIER ISLOW_MULT_TYPE; /* short or int, whichever is faster */
66#if BITS_IN_JSAMPLE == 8
67typedef MULTIPLIER IFAST_MULT_TYPE; /* 16 bits is OK, use short if faster */
68#define IFAST_SCALE_BITS 2 /* fractional bits in scale factors */
69#else
70typedef INT32 IFAST_MULT_TYPE; /* need 32 bits for scaled quantizers */
71#define IFAST_SCALE_BITS 13 /* fractional bits in scale factors */
72#endif
73typedef FAST_FLOAT FLOAT_MULT_TYPE; /* preferred floating type */
74
75
76/*
77 * Each IDCT routine is responsible for range-limiting its results and
78 * converting them to unsigned form (0..MAXJSAMPLE). The raw outputs could
79 * be quite far out of range if the input data is corrupt, so a bulletproof
80 * range-limiting step is required. We use a mask-and-table-lookup method
81 * to do the combined operations quickly. See the comments with
82 * prepare_range_limit_table (in jdmaster.c) for more info.
83 */
84
85#define IDCT_range_limit(cinfo) ((cinfo)->sample_range_limit + CENTERJSAMPLE)
86
87#define RANGE_MASK (MAXJSAMPLE * 4 + 3) /* 2 bits wider than legal samples */
88
89
90/* Short forms of external names for systems with brain-damaged linkers. */
91
92#ifdef NEED_SHORT_EXTERNAL_NAMES
93#define jpeg_fdct_islow jFDislow
94#define jpeg_fdct_ifast jFDifast
95#define jpeg_fdct_float jFDfloat
96#define jpeg_fdct_7x7 jFD7x7
97#define jpeg_fdct_6x6 jFD6x6
98#define jpeg_fdct_5x5 jFD5x5
99#define jpeg_fdct_4x4 jFD4x4
100#define jpeg_fdct_3x3 jFD3x3
101#define jpeg_fdct_2x2 jFD2x2
102#define jpeg_fdct_1x1 jFD1x1
103#define jpeg_fdct_9x9 jFD9x9
104#define jpeg_fdct_10x10 jFD10x10
105#define jpeg_fdct_11x11 jFD11x11
106#define jpeg_fdct_12x12 jFD12x12
107#define jpeg_fdct_13x13 jFD13x13
108#define jpeg_fdct_14x14 jFD14x14
109#define jpeg_fdct_15x15 jFD15x15
110#define jpeg_fdct_16x16 jFD16x16
111#define jpeg_fdct_16x8 jFD16x8
112#define jpeg_fdct_14x7 jFD14x7
113#define jpeg_fdct_12x6 jFD12x6
114#define jpeg_fdct_10x5 jFD10x5
115#define jpeg_fdct_8x4 jFD8x4
116#define jpeg_fdct_6x3 jFD6x3
117#define jpeg_fdct_4x2 jFD4x2
118#define jpeg_fdct_2x1 jFD2x1
119#define jpeg_fdct_8x16 jFD8x16
120#define jpeg_fdct_7x14 jFD7x14
121#define jpeg_fdct_6x12 jFD6x12
122#define jpeg_fdct_5x10 jFD5x10
123#define jpeg_fdct_4x8 jFD4x8
124#define jpeg_fdct_3x6 jFD3x6
125#define jpeg_fdct_2x4 jFD2x4
126#define jpeg_fdct_1x2 jFD1x2
127#define jpeg_idct_islow jRDislow
128#define jpeg_idct_ifast jRDifast
129#define jpeg_idct_float jRDfloat
130#define jpeg_idct_7x7 jRD7x7
131#define jpeg_idct_6x6 jRD6x6
132#define jpeg_idct_5x5 jRD5x5
133#define jpeg_idct_4x4 jRD4x4
134#define jpeg_idct_3x3 jRD3x3
135#define jpeg_idct_2x2 jRD2x2
136#define jpeg_idct_1x1 jRD1x1
137#define jpeg_idct_9x9 jRD9x9
138#define jpeg_idct_10x10 jRD10x10
139#define jpeg_idct_11x11 jRD11x11
140#define jpeg_idct_12x12 jRD12x12
141#define jpeg_idct_13x13 jRD13x13
142#define jpeg_idct_14x14 jRD14x14
143#define jpeg_idct_15x15 jRD15x15
144#define jpeg_idct_16x16 jRD16x16
145#define jpeg_idct_16x8 jRD16x8
146#define jpeg_idct_14x7 jRD14x7
147#define jpeg_idct_12x6 jRD12x6
148#define jpeg_idct_10x5 jRD10x5
149#define jpeg_idct_8x4 jRD8x4
150#define jpeg_idct_6x3 jRD6x3
151#define jpeg_idct_4x2 jRD4x2
152#define jpeg_idct_2x1 jRD2x1
153#define jpeg_idct_8x16 jRD8x16
154#define jpeg_idct_7x14 jRD7x14
155#define jpeg_idct_6x12 jRD6x12
156#define jpeg_idct_5x10 jRD5x10
157#define jpeg_idct_4x8 jRD4x8
158#define jpeg_idct_3x6 jRD3x8
159#define jpeg_idct_2x4 jRD2x4
160#define jpeg_idct_1x2 jRD1x2
161#endif /* NEED_SHORT_EXTERNAL_NAMES */
162
163/* Extern declarations for the forward and inverse DCT routines. */
164
165EXTERN(void) jpeg_fdct_islow
166 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
167EXTERN(void) jpeg_fdct_ifast
168 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
169EXTERN(void) jpeg_fdct_float
170 JPP((FAST_FLOAT * data, JSAMPARRAY sample_data, JDIMENSION start_col));
171EXTERN(void) jpeg_fdct_7x7
172 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
173EXTERN(void) jpeg_fdct_6x6
174 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
175EXTERN(void) jpeg_fdct_5x5
176 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
177EXTERN(void) jpeg_fdct_4x4
178 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
179EXTERN(void) jpeg_fdct_3x3
180 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
181EXTERN(void) jpeg_fdct_2x2
182 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
183EXTERN(void) jpeg_fdct_1x1
184 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
185EXTERN(void) jpeg_fdct_9x9
186 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
187EXTERN(void) jpeg_fdct_10x10
188 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
189EXTERN(void) jpeg_fdct_11x11
190 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
191EXTERN(void) jpeg_fdct_12x12
192 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
193EXTERN(void) jpeg_fdct_13x13
194 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
195EXTERN(void) jpeg_fdct_14x14
196 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
197EXTERN(void) jpeg_fdct_15x15
198 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
199EXTERN(void) jpeg_fdct_16x16
200 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
201EXTERN(void) jpeg_fdct_16x8
202 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
203EXTERN(void) jpeg_fdct_14x7
204 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
205EXTERN(void) jpeg_fdct_12x6
206 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
207EXTERN(void) jpeg_fdct_10x5
208 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
209EXTERN(void) jpeg_fdct_8x4
210 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
211EXTERN(void) jpeg_fdct_6x3
212 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
213EXTERN(void) jpeg_fdct_4x2
214 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
215EXTERN(void) jpeg_fdct_2x1
216 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
217EXTERN(void) jpeg_fdct_8x16
218 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
219EXTERN(void) jpeg_fdct_7x14
220 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
221EXTERN(void) jpeg_fdct_6x12
222 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
223EXTERN(void) jpeg_fdct_5x10
224 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
225EXTERN(void) jpeg_fdct_4x8
226 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
227EXTERN(void) jpeg_fdct_3x6
228 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
229EXTERN(void) jpeg_fdct_2x4
230 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
231EXTERN(void) jpeg_fdct_1x2
232 JPP((DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col));
233
234EXTERN(void) jpeg_idct_islow
235 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
236 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
237EXTERN(void) jpeg_idct_ifast
238 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
239 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
240EXTERN(void) jpeg_idct_float
241 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
242 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
243EXTERN(void) jpeg_idct_7x7
244 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
245 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
246EXTERN(void) jpeg_idct_6x6
247 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
248 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
249EXTERN(void) jpeg_idct_5x5
250 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
251 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
252EXTERN(void) jpeg_idct_4x4
253 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
254 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
255EXTERN(void) jpeg_idct_3x3
256 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
257 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
258EXTERN(void) jpeg_idct_2x2
259 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
260 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
261EXTERN(void) jpeg_idct_1x1
262 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
263 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
264EXTERN(void) jpeg_idct_9x9
265 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
266 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
267EXTERN(void) jpeg_idct_10x10
268 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
269 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
270EXTERN(void) jpeg_idct_11x11
271 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
272 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
273EXTERN(void) jpeg_idct_12x12
274 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
275 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
276EXTERN(void) jpeg_idct_13x13
277 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
278 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
279EXTERN(void) jpeg_idct_14x14
280 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
281 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
282EXTERN(void) jpeg_idct_15x15
283 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
284 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
285EXTERN(void) jpeg_idct_16x16
286 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
287 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
288EXTERN(void) jpeg_idct_16x8
289 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
290 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
291EXTERN(void) jpeg_idct_14x7
292 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
293 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
294EXTERN(void) jpeg_idct_12x6
295 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
296 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
297EXTERN(void) jpeg_idct_10x5
298 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
299 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
300EXTERN(void) jpeg_idct_8x4
301 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
302 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
303EXTERN(void) jpeg_idct_6x3
304 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
305 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
306EXTERN(void) jpeg_idct_4x2
307 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
308 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
309EXTERN(void) jpeg_idct_2x1
310 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
311 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
312EXTERN(void) jpeg_idct_8x16
313 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
314 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
315EXTERN(void) jpeg_idct_7x14
316 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
317 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
318EXTERN(void) jpeg_idct_6x12
319 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
320 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
321EXTERN(void) jpeg_idct_5x10
322 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
323 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
324EXTERN(void) jpeg_idct_4x8
325 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
326 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
327EXTERN(void) jpeg_idct_3x6
328 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
329 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
330EXTERN(void) jpeg_idct_2x4
331 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
332 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
333EXTERN(void) jpeg_idct_1x2
334 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
335 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
336
337
338/*
339 * Macros for handling fixed-point arithmetic; these are used by many
340 * but not all of the DCT/IDCT modules.
341 *
342 * All values are expected to be of type INT32.
343 * Fractional constants are scaled left by CONST_BITS bits.
344 * CONST_BITS is defined within each module using these macros,
345 * and may differ from one module to the next.
346 */
347
348#define ONE ((INT32) 1)
349#define CONST_SCALE (ONE << CONST_BITS)
350
351/* Convert a positive real constant to an integer scaled by CONST_SCALE.
352 * Caution: some C compilers fail to reduce "FIX(constant)" at compile time,
353 * thus causing a lot of useless floating-point operations at run time.
354 */
355
356#define FIX(x) ((INT32) ((x) * CONST_SCALE + 0.5))
357
358/* Descale and correctly round an INT32 value that's scaled by N bits.
359 * We assume RIGHT_SHIFT rounds towards minus infinity, so adding
360 * the fudge factor is correct for either sign of X.
361 */
362
363#define DESCALE(x,n) RIGHT_SHIFT((x) + (ONE << ((n)-1)), n)
364
365/* Multiply an INT32 variable by an INT32 constant to yield an INT32 result.
366 * This macro is used only when the two inputs will actually be no more than
367 * 16 bits wide, so that a 16x16->32 bit multiply can be used instead of a
368 * full 32x32 multiply. This provides a useful speedup on many machines.
369 * Unfortunately there is no way to specify a 16x16->32 multiply portably
370 * in C, but some C compilers will do the right thing if you provide the
371 * correct combination of casts.
372 */
373
374#ifdef SHORTxSHORT_32 /* may work if 'int' is 32 bits */
375#define MULTIPLY16C16(var,const) (((INT16) (var)) * ((INT16) (const)))
376#endif
377#ifdef SHORTxLCONST_32 /* known to work with Microsoft C 6.0 */
378#define MULTIPLY16C16(var,const) (((INT16) (var)) * ((INT32) (const)))
379#endif
380
381#ifndef MULTIPLY16C16 /* default definition */
382#define MULTIPLY16C16(var,const) ((var) * (const))
383#endif
384
385/* Same except both inputs are variables. */
386
387#ifdef SHORTxSHORT_32 /* may work if 'int' is 32 bits */
388#define MULTIPLY16V16(var1,var2) (((INT16) (var1)) * ((INT16) (var2)))
389#endif
390
391#ifndef MULTIPLY16V16 /* default definition */
392#define MULTIPLY16V16(var1,var2) ((var1) * (var2))
393#endif
394