openshot-audio  0.1.2
jdct.h
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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 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.
27  */
28 
29 #ifndef __jdct_h__
30 #define __jdct_h__
31 
32 #if BITS_IN_JSAMPLE == 8
33 typedef int DCTELEM; /* 16 or 32 bits is fine */
34 #else
35 typedef INT32 DCTELEM; /* must have 32 bits */
36 #endif
37 
38 typedef JMETHOD(void, forward_DCT_method_ptr, (DCTELEM * data));
39 typedef JMETHOD(void, float_DCT_method_ptr, (FAST_FLOAT * data));
40 
41 
42 /*
43  * An inverse DCT routine is given a pointer to the input JBLOCK and a pointer
44  * to an output sample array. The routine must dequantize the input data as
45  * well as perform the IDCT; for dequantization, it uses the multiplier table
46  * pointed to by compptr->dct_table. The output data is to be placed into the
47  * sample array starting at a specified column. (Any row offset needed will
48  * be applied to the array pointer before it is passed to the IDCT code.)
49  * Note that the number of samples emitted by the IDCT routine is
50  * DCT_scaled_size * DCT_scaled_size.
51  */
52 
53 /* typedef inverse_DCT_method_ptr is declared in jpegint.h */
54 
55 /*
56  * Each IDCT routine has its own ideas about the best dct_table element type.
57  */
58 
59 typedef MULTIPLIER ISLOW_MULT_TYPE; /* short or int, whichever is faster */
60 #if BITS_IN_JSAMPLE == 8
61 typedef MULTIPLIER IFAST_MULT_TYPE; /* 16 bits is OK, use short if faster */
62 #define IFAST_SCALE_BITS 2 /* fractional bits in scale factors */
63 #else
64 typedef INT32 IFAST_MULT_TYPE; /* need 32 bits for scaled quantizers */
65 #define IFAST_SCALE_BITS 13 /* fractional bits in scale factors */
66 #endif
67 typedef FAST_FLOAT FLOAT_MULT_TYPE; /* preferred floating type */
68 
69 
70 /*
71  * Each IDCT routine is responsible for range-limiting its results and
72  * converting them to unsigned form (0..MAXJSAMPLE). The raw outputs could
73  * be quite far out of range if the input data is corrupt, so a bulletproof
74  * range-limiting step is required. We use a mask-and-table-lookup method
75  * to do the combined operations quickly. See the comments with
76  * prepare_range_limit_table (in jdmaster.c) for more info.
77  */
78 
79 #define IDCT_range_limit(cinfo) ((cinfo)->sample_range_limit + CENTERJSAMPLE)
80 
81 #define RANGE_MASK (MAXJSAMPLE * 4 + 3) /* 2 bits wider than legal samples */
82 
83 
84 /* Short forms of external names for systems with brain-damaged linkers. */
85 
86 #ifdef NEED_SHORT_EXTERNAL_NAMES
87 #define jpeg_fdct_islow jFDislow
88 #define jpeg_fdct_ifast jFDifast
89 #define jpeg_fdct_float jFDfloat
90 #define jpeg_idct_islow jRDislow
91 #define jpeg_idct_ifast jRDifast
92 #define jpeg_idct_float jRDfloat
93 #define jpeg_idct_4x4 jRD4x4
94 #define jpeg_idct_2x2 jRD2x2
95 #define jpeg_idct_1x1 jRD1x1
96 #endif /* NEED_SHORT_EXTERNAL_NAMES */
97 
98 /* Extern declarations for the forward and inverse DCT routines. */
99 
101 EXTERN(void) jpeg_fdct_ifast JPP((DCTELEM * data));
102 EXTERN(void) jpeg_fdct_float JPP((FAST_FLOAT * data));
103 
108  JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
109  JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
111  JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
112  JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
113 EXTERN(void) jpeg_idct_4x4
114  JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
115  JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
116 EXTERN(void) jpeg_idct_2x2
117  JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
118  JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
119 EXTERN(void) jpeg_idct_1x1
120  JPP((j_decompress_ptr cinfo, jpeg_component_info * compptr,
121  JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col));
122 
123 
124 /*
125  * Macros for handling fixed-point arithmetic; these are used by many
126  * but not all of the DCT/IDCT modules.
127  *
128  * All values are expected to be of type INT32.
129  * Fractional constants are scaled left by CONST_BITS bits.
130  * CONST_BITS is defined within each module using these macros,
131  * and may differ from one module to the next.
132  */
133 
134 #define ONE ((INT32) 1)
135 #define CONST_SCALE (ONE << CONST_BITS)
136 
137 /* Convert a positive real constant to an integer scaled by CONST_SCALE.
138  * Caution: some C compilers fail to reduce "FIX(constant)" at compile time,
139  * thus causing a lot of useless floating-point operations at run time.
140  */
141 
142 #define FIX(x) ((INT32) ((x) * CONST_SCALE + 0.5))
143 
144 /* Descale and correctly round an INT32 value that's scaled by N bits.
145  * We assume RIGHT_SHIFT rounds towards minus infinity, so adding
146  * the fudge factor is correct for either sign of X.
147  */
148 
149 #define DESCALE(x,n) RIGHT_SHIFT((x) + (ONE << ((n)-1)), n)
150 
151 /* Multiply an INT32 variable by an INT32 constant to yield an INT32 result.
152  * This macro is used only when the two inputs will actually be no more than
153  * 16 bits wide, so that a 16x16->32 bit multiply can be used instead of a
154  * full 32x32 multiply. This provides a useful speedup on many machines.
155  * Unfortunately there is no way to specify a 16x16->32 multiply portably
156  * in C, but some C compilers will do the right thing if you provide the
157  * correct combination of casts.
158  */
159 
160 #ifdef SHORTxSHORT_32 /* may work if 'int' is 32 bits */
161 #define MULTIPLY16C16(var,const) (((INT16) (var)) * ((INT16) (const)))
162 #endif
163 #ifdef SHORTxLCONST_32 /* known to work with Microsoft C 6.0 */
164 #define MULTIPLY16C16(var,const) (((INT16) (var)) * ((INT32) (const)))
165 #endif
166 
167 #ifndef MULTIPLY16C16 /* default definition */
168 #define MULTIPLY16C16(var,const) ((var) * (const))
169 #endif
170 
171 /* Same except both inputs are variables. */
172 
173 #ifdef SHORTxSHORT_32 /* may work if 'int' is 32 bits */
174 #define MULTIPLY16V16(var1,var2) (((INT16) (var1)) * ((INT16) (var2)))
175 #endif
176 
177 #ifndef MULTIPLY16V16 /* default definition */
178 #define MULTIPLY16V16(var1,var2) ((var1) * (var2))
179 #endif
180 
181 
182 #endif
typedef JMETHOD(void, forward_DCT_method_ptr,(DCTELEM *data))
jpeg_component_info JCOEFPTR coef_block
Definition: jdct.h:105
jpeg_idct_1x1(j_decompress_ptr cinfo, jpeg_component_info *compptr, JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)
Definition: jidctred.c:379
INT32 DCTELEM
Definition: jdct.h:35
jpeg_idct_islow(j_decompress_ptr cinfo, jpeg_component_info *compptr, JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)
Definition: jidctint.c:148
long INT32
Definition: jmorecfg.h:161
jpeg_component_info * compptr
Definition: jdct.h:105
jpeg_component_info JCOEFPTR JSAMPARRAY JDIMENSION output_col
Definition: jdct.h:105
jpeg_fdct_float(FAST_FLOAT *data)
Definition: jfdctflt.c:59
INT32 IFAST_MULT_TYPE
Definition: jdct.h:64
MULTIPLIER ISLOW_MULT_TYPE
Definition: jdct.h:59
jpeg_idct_4x4(j_decompress_ptr cinfo, jpeg_component_info *compptr, JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)
Definition: jidctred.c:118
JCOEF FAR * JCOEFPTR
Definition: jpeglib.h:75
#define JPP(arglist)
Definition: juce_JPEGLoader.cpp:818
FAST_FLOAT FLOAT_MULT_TYPE
Definition: jdct.h:67
jpeg_fdct_islow(DCTELEM *data)
Definition: jfdctint.c:140
JSAMPROW * JSAMPARRAY
Definition: jpeglib.h:67
Definition: jpeglib.h:116
EXTERN(void) jpeg_fdct_islow JPP((DCTELEM *data))
jpeg_idct_2x2(j_decompress_ptr cinfo, jpeg_component_info *compptr, JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)
Definition: jidctred.c:271
Definition: jpeglib.h:411
JSAMPIMAGE data
Definition: jpeglib.h:945
jpeg_component_info JCOEFPTR JSAMPARRAY output_buf
Definition: jdct.h:105
unsigned int JDIMENSION
Definition: jmorecfg.h:171
jpeg_fdct_ifast(DCTELEM *data)
Definition: jfdctfst.c:114
jpeg_idct_float(j_decompress_ptr cinfo, jpeg_component_info *compptr, JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)
Definition: jidctflt.c:68
jpeg_idct_ifast(j_decompress_ptr cinfo, jpeg_component_info *compptr, JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col)
Definition: jidctfst.c:168