media/libjpeg/jdct.h@b8a032363ba2
media/libjpeg/jdct.h
Thu, 22 Jan 2015 13:21:57 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Thu, 22 Jan 2015 13:21:57 +0100
- branch
- TOR_BUG_9701
- changeset 15
- b8a032363ba2
- permissions
- -rw-r--r--
Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6
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 */
16 /*
17 * A forward DCT routine is given a pointer to a work area of type DCTELEM[];
18 * the DCT is to be performed in-place in that buffer. Type DCTELEM is int
19 * for 8-bit samples, INT32 for 12-bit samples. (NOTE: Floating-point DCT
20 * implementations use an array of type FAST_FLOAT, instead.)
21 * The DCT inputs are expected to be signed (range +-CENTERJSAMPLE).
22 * The DCT outputs are returned scaled up by a factor of 8; they therefore
23 * have a range of +-8K for 8-bit data, +-128K for 12-bit data. This
24 * convention improves accuracy in integer implementations and saves some
25 * work in floating-point ones.
26 * Quantization of the output coefficients is done by jcdctmgr.c. This
27 * step requires an unsigned type and also one with twice the bits.
28 */
30 #if BITS_IN_JSAMPLE == 8
31 #ifndef WITH_SIMD
32 typedef int DCTELEM; /* 16 or 32 bits is fine */
33 typedef unsigned int UDCTELEM;
34 typedef unsigned long long UDCTELEM2;
35 #else
36 typedef short DCTELEM; /* prefer 16 bit with SIMD for parellelism */
37 typedef unsigned short UDCTELEM;
38 typedef unsigned int UDCTELEM2;
39 #endif
40 #else
41 typedef INT32 DCTELEM; /* must have 32 bits */
42 typedef UINT32 UDCTELEM;
43 typedef unsigned long long UDCTELEM2;
44 #endif
47 /*
48 * An inverse DCT routine is given a pointer to the input JBLOCK and a pointer
49 * to an output sample array. The routine must dequantize the input data as
50 * well as perform the IDCT; for dequantization, it uses the multiplier table
51 * pointed to by compptr->dct_table. The output data is to be placed into the
52 * sample array starting at a specified column. (Any row offset needed will
53 * be applied to the array pointer before it is passed to the IDCT code.)
54 * Note that the number of samples emitted by the IDCT routine is
55 * DCT_scaled_size * DCT_scaled_size.
56 */
58 /* typedef inverse_DCT_method_ptr is declared in jpegint.h */
60 /*
61 * Each IDCT routine has its own ideas about the best dct_table element type.
62 */
64 typedef MULTIPLIER ISLOW_MULT_TYPE; /* short or int, whichever is faster */
65 #if BITS_IN_JSAMPLE == 8
66 typedef MULTIPLIER IFAST_MULT_TYPE; /* 16 bits is OK, use short if faster */
67 #define IFAST_SCALE_BITS 2 /* fractional bits in scale factors */
68 #else
69 typedef INT32 IFAST_MULT_TYPE; /* need 32 bits for scaled quantizers */
70 #define IFAST_SCALE_BITS 13 /* fractional bits in scale factors */
71 #endif
72 typedef FAST_FLOAT FLOAT_MULT_TYPE; /* preferred floating type */
75 /*
76 * Each IDCT routine is responsible for range-limiting its results and
77 * converting them to unsigned form (0..MAXJSAMPLE). The raw outputs could
78 * be quite far out of range if the input data is corrupt, so a bulletproof
79 * range-limiting step is required. We use a mask-and-table-lookup method
80 * to do the combined operations quickly. See the comments with
81 * prepare_range_limit_table (in jdmaster.c) for more info.
82 */
84 #define IDCT_range_limit(cinfo) ((cinfo)->sample_range_limit + CENTERJSAMPLE)
86 #define RANGE_MASK (MAXJSAMPLE * 4 + 3) /* 2 bits wider than legal samples */
89 /* Short forms of external names for systems with brain-damaged linkers. */
91 #ifdef NEED_SHORT_EXTERNAL_NAMES
92 #define jpeg_fdct_islow jFDislow
93 #define jpeg_fdct_ifast jFDifast
94 #define jpeg_fdct_float jFDfloat
95 #define jpeg_idct_islow jRDislow
96 #define jpeg_idct_ifast jRDifast
97 #define jpeg_idct_float jRDfloat
98 #define jpeg_idct_7x7 jRD7x7
99 #define jpeg_idct_6x6 jRD6x6
100 #define jpeg_idct_5x5 jRD5x5
101 #define jpeg_idct_4x4 jRD4x4
102 #define jpeg_idct_3x3 jRD3x3
103 #define jpeg_idct_2x2 jRD2x2
104 #define jpeg_idct_1x1 jRD1x1
105 #define jpeg_idct_9x9 jRD9x9
106 #define jpeg_idct_10x10 jRD10x10
107 #define jpeg_idct_11x11 jRD11x11
108 #define jpeg_idct_12x12 jRD12x12
109 #define jpeg_idct_13x13 jRD13x13
110 #define jpeg_idct_14x14 jRD14x14
111 #define jpeg_idct_15x15 jRD15x15
112 #define jpeg_idct_16x16 jRD16x16
113 #endif /* NEED_SHORT_EXTERNAL_NAMES */
115 /* Extern declarations for the forward and inverse DCT routines. */
117 EXTERN(void) jpeg_fdct_islow JPP((DCTELEM * data));
118 EXTERN(void) jpeg_fdct_ifast JPP((DCTELEM * data));
119 EXTERN(void) jpeg_fdct_float JPP((FAST_FLOAT * data));
121 EXTERN(void) jpeg_idct_islow
122 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
123 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
124 EXTERN(void) jpeg_idct_ifast
125 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
126 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
127 EXTERN(void) jpeg_idct_float
128 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
129 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
130 EXTERN(void) jpeg_idct_7x7
131 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
132 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
133 EXTERN(void) jpeg_idct_6x6
134 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
135 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
136 EXTERN(void) jpeg_idct_5x5
137 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
138 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
139 EXTERN(void) jpeg_idct_4x4
140 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
141 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
142 EXTERN(void) jpeg_idct_3x3
143 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
144 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
145 EXTERN(void) jpeg_idct_2x2
146 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
147 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
148 EXTERN(void) jpeg_idct_1x1
149 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
150 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
151 EXTERN(void) jpeg_idct_9x9
152 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
153 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
154 EXTERN(void) jpeg_idct_10x10
155 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
156 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
157 EXTERN(void) jpeg_idct_11x11
158 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
159 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
160 EXTERN(void) jpeg_idct_12x12
161 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
162 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
163 EXTERN(void) jpeg_idct_13x13
164 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
165 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
166 EXTERN(void) jpeg_idct_14x14
167 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
168 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
169 EXTERN(void) jpeg_idct_15x15
170 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
171 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
172 EXTERN(void) jpeg_idct_16x16
173 JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
174 JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
177 /*
178 * Macros for handling fixed-point arithmetic; these are used by many
179 * but not all of the DCT/IDCT modules.
180 *
181 * All values are expected to be of type INT32.
182 * Fractional constants are scaled left by CONST_BITS bits.
183 * CONST_BITS is defined within each module using these macros,
184 * and may differ from one module to the next.
185 */
187 #define ONE ((INT32) 1)
188 #define CONST_SCALE (ONE << CONST_BITS)
190 /* Convert a positive real constant to an integer scaled by CONST_SCALE.
191 * Caution: some C compilers fail to reduce "FIX(constant)" at compile time,
192 * thus causing a lot of useless floating-point operations at run time.
193 */
195 #define FIX(x) ((INT32) ((x) * CONST_SCALE + 0.5))
197 /* Descale and correctly round an INT32 value that's scaled by N bits.
198 * We assume RIGHT_SHIFT rounds towards minus infinity, so adding
199 * the fudge factor is correct for either sign of X.
200 */
202 #define DESCALE(x,n) RIGHT_SHIFT((x) + (ONE << ((n)-1)), n)
204 /* Multiply an INT32 variable by an INT32 constant to yield an INT32 result.
205 * This macro is used only when the two inputs will actually be no more than
206 * 16 bits wide, so that a 16x16->32 bit multiply can be used instead of a
207 * full 32x32 multiply. This provides a useful speedup on many machines.
208 * Unfortunately there is no way to specify a 16x16->32 multiply portably
209 * in C, but some C compilers will do the right thing if you provide the
210 * correct combination of casts.
211 */
213 #ifdef SHORTxSHORT_32 /* may work if 'int' is 32 bits */
214 #define MULTIPLY16C16(var,const) (((INT16) (var)) * ((INT16) (const)))
215 #endif
216 #ifdef SHORTxLCONST_32 /* known to work with Microsoft C 6.0 */
217 #define MULTIPLY16C16(var,const) (((INT16) (var)) * ((INT32) (const)))
218 #endif
220 #ifndef MULTIPLY16C16 /* default definition */
221 #define MULTIPLY16C16(var,const) ((var) * (const))
222 #endif
224 /* Same except both inputs are variables. */
226 #ifdef SHORTxSHORT_32 /* may work if 'int' is 32 bits */
227 #define MULTIPLY16V16(var1,var2) (((INT16) (var1)) * ((INT16) (var2)))
228 #endif
230 #ifndef MULTIPLY16V16 /* default definition */
231 #define MULTIPLY16V16(var1,var2) ((var1) * (var2))
232 #endif
