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.
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).
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.
34 #if BITS_IN_JSAMPLE == 8
35 typedef int DCTELEM
; /* 16 or 32 bits is fine */
37 typedef INT32 DCTELEM
; /* must have 32 bits */
40 typedef JMETHOD(void, forward_DCT_method_ptr
, (DCTELEM
* data
,
41 JSAMPARRAY sample_data
,
42 JDIMENSION start_col
));
43 typedef JMETHOD(void, float_DCT_method_ptr
, (FAST_FLOAT
* data
,
44 JSAMPARRAY sample_data
,
45 JDIMENSION start_col
));
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.
59 /* typedef inverse_DCT_method_ptr is declared in jpegint.h */
62 * Each IDCT routine has its own ideas about the best dct_table element type.
65 typedef MULTIPLIER ISLOW_MULT_TYPE
; /* short or int, whichever is faster */
66 #if BITS_IN_JSAMPLE == 8
67 typedef MULTIPLIER IFAST_MULT_TYPE
; /* 16 bits is OK, use short if faster */
68 #define IFAST_SCALE_BITS 2 /* fractional bits in scale factors */
70 typedef INT32 IFAST_MULT_TYPE
; /* need 32 bits for scaled quantizers */
71 #define IFAST_SCALE_BITS 13 /* fractional bits in scale factors */
73 typedef FAST_FLOAT FLOAT_MULT_TYPE
; /* preferred floating type */
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.
85 #define IDCT_range_limit(cinfo) ((cinfo)->sample_range_limit + CENTERJSAMPLE)
87 #define RANGE_MASK (MAXJSAMPLE * 4 + 3) /* 2 bits wider than legal samples */
90 /* Short forms of external names for systems with brain-damaged linkers. */
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 */
163 /* Extern declarations for the forward and inverse DCT routines. */
165 EXTERN(void) jpeg_fdct_islow
166 JPP((DCTELEM
* data
, JSAMPARRAY sample_data
, JDIMENSION start_col
));
167 EXTERN(void) jpeg_fdct_ifast
168 JPP((DCTELEM
* data
, JSAMPARRAY sample_data
, JDIMENSION start_col
));
169 EXTERN(void) jpeg_fdct_float
170 JPP((FAST_FLOAT
* data
, JSAMPARRAY sample_data
, JDIMENSION start_col
));
171 EXTERN(void) jpeg_fdct_7x7
172 JPP((DCTELEM
* data
, JSAMPARRAY sample_data
, JDIMENSION start_col
));
173 EXTERN(void) jpeg_fdct_6x6
174 JPP((DCTELEM
* data
, JSAMPARRAY sample_data
, JDIMENSION start_col
));
175 EXTERN(void) jpeg_fdct_5x5
176 JPP((DCTELEM
* data
, JSAMPARRAY sample_data
, JDIMENSION start_col
));
177 EXTERN(void) jpeg_fdct_4x4
178 JPP((DCTELEM
* data
, JSAMPARRAY sample_data
, JDIMENSION start_col
));
179 EXTERN(void) jpeg_fdct_3x3
180 JPP((DCTELEM
* data
, JSAMPARRAY sample_data
, JDIMENSION start_col
));
181 EXTERN(void) jpeg_fdct_2x2
182 JPP((DCTELEM
* data
, JSAMPARRAY sample_data
, JDIMENSION start_col
));
183 EXTERN(void) jpeg_fdct_1x1
184 JPP((DCTELEM
* data
, JSAMPARRAY sample_data
, JDIMENSION start_col
));
185 EXTERN(void) jpeg_fdct_9x9
186 JPP((DCTELEM
* data
, JSAMPARRAY sample_data
, JDIMENSION start_col
));
187 EXTERN(void) jpeg_fdct_10x10
188 JPP((DCTELEM
* data
, JSAMPARRAY sample_data
, JDIMENSION start_col
));
189 EXTERN(void) jpeg_fdct_11x11
190 JPP((DCTELEM
* data
, JSAMPARRAY sample_data
, JDIMENSION start_col
));
191 EXTERN(void) jpeg_fdct_12x12
192 JPP((DCTELEM
* data
, JSAMPARRAY sample_data
, JDIMENSION start_col
));
193 EXTERN(void) jpeg_fdct_13x13
194 JPP((DCTELEM
* data
, JSAMPARRAY sample_data
, JDIMENSION start_col
));
195 EXTERN(void) jpeg_fdct_14x14
196 JPP((DCTELEM
* data
, JSAMPARRAY sample_data
, JDIMENSION start_col
));
197 EXTERN(void) jpeg_fdct_15x15
198 JPP((DCTELEM
* data
, JSAMPARRAY sample_data
, JDIMENSION start_col
));
199 EXTERN(void) jpeg_fdct_16x16
200 JPP((DCTELEM
* data
, JSAMPARRAY sample_data
, JDIMENSION start_col
));
201 EXTERN(void) jpeg_fdct_16x8
202 JPP((DCTELEM
* data
, JSAMPARRAY sample_data
, JDIMENSION start_col
));
203 EXTERN(void) jpeg_fdct_14x7
204 JPP((DCTELEM
* data
, JSAMPARRAY sample_data
, JDIMENSION start_col
));
205 EXTERN(void) jpeg_fdct_12x6
206 JPP((DCTELEM
* data
, JSAMPARRAY sample_data
, JDIMENSION start_col
));
207 EXTERN(void) jpeg_fdct_10x5
208 JPP((DCTELEM
* data
, JSAMPARRAY sample_data
, JDIMENSION start_col
));
209 EXTERN(void) jpeg_fdct_8x4
210 JPP((DCTELEM
* data
, JSAMPARRAY sample_data
, JDIMENSION start_col
));
211 EXTERN(void) jpeg_fdct_6x3
212 JPP((DCTELEM
* data
, JSAMPARRAY sample_data
, JDIMENSION start_col
));
213 EXTERN(void) jpeg_fdct_4x2
214 JPP((DCTELEM
* data
, JSAMPARRAY sample_data
, JDIMENSION start_col
));
215 EXTERN(void) jpeg_fdct_2x1
216 JPP((DCTELEM
* data
, JSAMPARRAY sample_data
, JDIMENSION start_col
));
217 EXTERN(void) jpeg_fdct_8x16
218 JPP((DCTELEM
* data
, JSAMPARRAY sample_data
, JDIMENSION start_col
));
219 EXTERN(void) jpeg_fdct_7x14
220 JPP((DCTELEM
* data
, JSAMPARRAY sample_data
, JDIMENSION start_col
));
221 EXTERN(void) jpeg_fdct_6x12
222 JPP((DCTELEM
* data
, JSAMPARRAY sample_data
, JDIMENSION start_col
));
223 EXTERN(void) jpeg_fdct_5x10
224 JPP((DCTELEM
* data
, JSAMPARRAY sample_data
, JDIMENSION start_col
));
225 EXTERN(void) jpeg_fdct_4x8
226 JPP((DCTELEM
* data
, JSAMPARRAY sample_data
, JDIMENSION start_col
));
227 EXTERN(void) jpeg_fdct_3x6
228 JPP((DCTELEM
* data
, JSAMPARRAY sample_data
, JDIMENSION start_col
));
229 EXTERN(void) jpeg_fdct_2x4
230 JPP((DCTELEM
* data
, JSAMPARRAY sample_data
, JDIMENSION start_col
));
231 EXTERN(void) jpeg_fdct_1x2
232 JPP((DCTELEM
* data
, JSAMPARRAY sample_data
, JDIMENSION start_col
));
234 EXTERN(void) jpeg_idct_islow
235 JPP((j_decompress_ptr cinfo
, jpeg_component_info
* compptr
,
236 JCOEFPTR coef_block
, JSAMPARRAY output_buf
, JDIMENSION output_col
));
237 EXTERN(void) jpeg_idct_ifast
238 JPP((j_decompress_ptr cinfo
, jpeg_component_info
* compptr
,
239 JCOEFPTR coef_block
, JSAMPARRAY output_buf
, JDIMENSION output_col
));
240 EXTERN(void) jpeg_idct_float
241 JPP((j_decompress_ptr cinfo
, jpeg_component_info
* compptr
,
242 JCOEFPTR coef_block
, JSAMPARRAY output_buf
, JDIMENSION output_col
));
243 EXTERN(void) jpeg_idct_7x7
244 JPP((j_decompress_ptr cinfo
, jpeg_component_info
* compptr
,
245 JCOEFPTR coef_block
, JSAMPARRAY output_buf
, JDIMENSION output_col
));
246 EXTERN(void) jpeg_idct_6x6
247 JPP((j_decompress_ptr cinfo
, jpeg_component_info
* compptr
,
248 JCOEFPTR coef_block
, JSAMPARRAY output_buf
, JDIMENSION output_col
));
249 EXTERN(void) jpeg_idct_5x5
250 JPP((j_decompress_ptr cinfo
, jpeg_component_info
* compptr
,
251 JCOEFPTR coef_block
, JSAMPARRAY output_buf
, JDIMENSION output_col
));
252 EXTERN(void) jpeg_idct_4x4
253 JPP((j_decompress_ptr cinfo
, jpeg_component_info
* compptr
,
254 JCOEFPTR coef_block
, JSAMPARRAY output_buf
, JDIMENSION output_col
));
255 EXTERN(void) jpeg_idct_3x3
256 JPP((j_decompress_ptr cinfo
, jpeg_component_info
* compptr
,
257 JCOEFPTR coef_block
, JSAMPARRAY output_buf
, JDIMENSION output_col
));
258 EXTERN(void) jpeg_idct_2x2
259 JPP((j_decompress_ptr cinfo
, jpeg_component_info
* compptr
,
260 JCOEFPTR coef_block
, JSAMPARRAY output_buf
, JDIMENSION output_col
));
261 EXTERN(void) jpeg_idct_1x1
262 JPP((j_decompress_ptr cinfo
, jpeg_component_info
* compptr
,
263 JCOEFPTR coef_block
, JSAMPARRAY output_buf
, JDIMENSION output_col
));
264 EXTERN(void) jpeg_idct_9x9
265 JPP((j_decompress_ptr cinfo
, jpeg_component_info
* compptr
,
266 JCOEFPTR coef_block
, JSAMPARRAY output_buf
, JDIMENSION output_col
));
267 EXTERN(void) jpeg_idct_10x10
268 JPP((j_decompress_ptr cinfo
, jpeg_component_info
* compptr
,
269 JCOEFPTR coef_block
, JSAMPARRAY output_buf
, JDIMENSION output_col
));
270 EXTERN(void) jpeg_idct_11x11
271 JPP((j_decompress_ptr cinfo
, jpeg_component_info
* compptr
,
272 JCOEFPTR coef_block
, JSAMPARRAY output_buf
, JDIMENSION output_col
));
273 EXTERN(void) jpeg_idct_12x12
274 JPP((j_decompress_ptr cinfo
, jpeg_component_info
* compptr
,
275 JCOEFPTR coef_block
, JSAMPARRAY output_buf
, JDIMENSION output_col
));
276 EXTERN(void) jpeg_idct_13x13
277 JPP((j_decompress_ptr cinfo
, jpeg_component_info
* compptr
,
278 JCOEFPTR coef_block
, JSAMPARRAY output_buf
, JDIMENSION output_col
));
279 EXTERN(void) jpeg_idct_14x14
280 JPP((j_decompress_ptr cinfo
, jpeg_component_info
* compptr
,
281 JCOEFPTR coef_block
, JSAMPARRAY output_buf
, JDIMENSION output_col
));
282 EXTERN(void) jpeg_idct_15x15
283 JPP((j_decompress_ptr cinfo
, jpeg_component_info
* compptr
,
284 JCOEFPTR coef_block
, JSAMPARRAY output_buf
, JDIMENSION output_col
));
285 EXTERN(void) jpeg_idct_16x16
286 JPP((j_decompress_ptr cinfo
, jpeg_component_info
* compptr
,
287 JCOEFPTR coef_block
, JSAMPARRAY output_buf
, JDIMENSION output_col
));
288 EXTERN(void) jpeg_idct_16x8
289 JPP((j_decompress_ptr cinfo
, jpeg_component_info
* compptr
,
290 JCOEFPTR coef_block
, JSAMPARRAY output_buf
, JDIMENSION output_col
));
291 EXTERN(void) jpeg_idct_14x7
292 JPP((j_decompress_ptr cinfo
, jpeg_component_info
* compptr
,
293 JCOEFPTR coef_block
, JSAMPARRAY output_buf
, JDIMENSION output_col
));
294 EXTERN(void) jpeg_idct_12x6
295 JPP((j_decompress_ptr cinfo
, jpeg_component_info
* compptr
,
296 JCOEFPTR coef_block
, JSAMPARRAY output_buf
, JDIMENSION output_col
));
297 EXTERN(void) jpeg_idct_10x5
298 JPP((j_decompress_ptr cinfo
, jpeg_component_info
* compptr
,
299 JCOEFPTR coef_block
, JSAMPARRAY output_buf
, JDIMENSION output_col
));
300 EXTERN(void) jpeg_idct_8x4
301 JPP((j_decompress_ptr cinfo
, jpeg_component_info
* compptr
,
302 JCOEFPTR coef_block
, JSAMPARRAY output_buf
, JDIMENSION output_col
));
303 EXTERN(void) jpeg_idct_6x3
304 JPP((j_decompress_ptr cinfo
, jpeg_component_info
* compptr
,
305 JCOEFPTR coef_block
, JSAMPARRAY output_buf
, JDIMENSION output_col
));
306 EXTERN(void) jpeg_idct_4x2
307 JPP((j_decompress_ptr cinfo
, jpeg_component_info
* compptr
,
308 JCOEFPTR coef_block
, JSAMPARRAY output_buf
, JDIMENSION output_col
));
309 EXTERN(void) jpeg_idct_2x1
310 JPP((j_decompress_ptr cinfo
, jpeg_component_info
* compptr
,
311 JCOEFPTR coef_block
, JSAMPARRAY output_buf
, JDIMENSION output_col
));
312 EXTERN(void) jpeg_idct_8x16
313 JPP((j_decompress_ptr cinfo
, jpeg_component_info
* compptr
,
314 JCOEFPTR coef_block
, JSAMPARRAY output_buf
, JDIMENSION output_col
));
315 EXTERN(void) jpeg_idct_7x14
316 JPP((j_decompress_ptr cinfo
, jpeg_component_info
* compptr
,
317 JCOEFPTR coef_block
, JSAMPARRAY output_buf
, JDIMENSION output_col
));
318 EXTERN(void) jpeg_idct_6x12
319 JPP((j_decompress_ptr cinfo
, jpeg_component_info
* compptr
,
320 JCOEFPTR coef_block
, JSAMPARRAY output_buf
, JDIMENSION output_col
));
321 EXTERN(void) jpeg_idct_5x10
322 JPP((j_decompress_ptr cinfo
, jpeg_component_info
* compptr
,
323 JCOEFPTR coef_block
, JSAMPARRAY output_buf
, JDIMENSION output_col
));
324 EXTERN(void) jpeg_idct_4x8
325 JPP((j_decompress_ptr cinfo
, jpeg_component_info
* compptr
,
326 JCOEFPTR coef_block
, JSAMPARRAY output_buf
, JDIMENSION output_col
));
327 EXTERN(void) jpeg_idct_3x6
328 JPP((j_decompress_ptr cinfo
, jpeg_component_info
* compptr
,
329 JCOEFPTR coef_block
, JSAMPARRAY output_buf
, JDIMENSION output_col
));
330 EXTERN(void) jpeg_idct_2x4
331 JPP((j_decompress_ptr cinfo
, jpeg_component_info
* compptr
,
332 JCOEFPTR coef_block
, JSAMPARRAY output_buf
, JDIMENSION output_col
));
333 EXTERN(void) jpeg_idct_1x2
334 JPP((j_decompress_ptr cinfo
, jpeg_component_info
* compptr
,
335 JCOEFPTR coef_block
, JSAMPARRAY output_buf
, JDIMENSION output_col
));
339 * Macros for handling fixed-point arithmetic; these are used by many
340 * but not all of the DCT/IDCT modules.
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.
348 #define ONE ((INT32) 1)
349 #define CONST_SCALE (ONE << CONST_BITS)
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.
356 #define FIX(x) ((INT32) ((x) * CONST_SCALE + 0.5))
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.
363 #define DESCALE(x,n) RIGHT_SHIFT((x) + (ONE << ((n)-1)), n)
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.
374 #ifdef SHORTxSHORT_32 /* may work if 'int' is 32 bits */
375 #define MULTIPLY16C16(var,const) (((INT16) (var)) * ((INT16) (const)))
377 #ifdef SHORTxLCONST_32 /* known to work with Microsoft C 6.0 */
378 #define MULTIPLY16C16(var,const) (((INT16) (var)) * ((INT32) (const)))
381 #ifndef MULTIPLY16C16 /* default definition */
382 #define MULTIPLY16C16(var,const) ((var) * (const))
385 /* Same except both inputs are variables. */
387 #ifdef SHORTxSHORT_32 /* may work if 'int' is 32 bits */
388 #define MULTIPLY16V16(var1,var2) (((INT16) (var1)) * ((INT16) (var2)))
391 #ifndef MULTIPLY16V16 /* default definition */
392 #define MULTIPLY16V16(var1,var2) ((var1) * (var2))