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Diffstat (limited to 'libraries/irrlicht-1.8/source/Irrlicht/jpeglib/jidctflt.c')
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diff --git a/libraries/irrlicht-1.8/source/Irrlicht/jpeglib/jidctflt.c b/libraries/irrlicht-1.8/source/Irrlicht/jpeglib/jidctflt.c new file mode 100644 index 0000000..f399600 --- /dev/null +++ b/libraries/irrlicht-1.8/source/Irrlicht/jpeglib/jidctflt.c | |||
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1 | /* | ||
2 | * jidctflt.c | ||
3 | * | ||
4 | * Copyright (C) 1994-1998, Thomas G. Lane. | ||
5 | * Modified 2010 by Guido Vollbeding. | ||
6 | * This file is part of the Independent JPEG Group's software. | ||
7 | * For conditions of distribution and use, see the accompanying README file. | ||
8 | * | ||
9 | * This file contains a floating-point implementation of the | ||
10 | * inverse DCT (Discrete Cosine Transform). In the IJG code, this routine | ||
11 | * must also perform dequantization of the input coefficients. | ||
12 | * | ||
13 | * This implementation should be more accurate than either of the integer | ||
14 | * IDCT implementations. However, it may not give the same results on all | ||
15 | * machines because of differences in roundoff behavior. Speed will depend | ||
16 | * on the hardware's floating point capacity. | ||
17 | * | ||
18 | * A 2-D IDCT can be done by 1-D IDCT on each column followed by 1-D IDCT | ||
19 | * on each row (or vice versa, but it's more convenient to emit a row at | ||
20 | * a time). Direct algorithms are also available, but they are much more | ||
21 | * complex and seem not to be any faster when reduced to code. | ||
22 | * | ||
23 | * This implementation is based on Arai, Agui, and Nakajima's algorithm for | ||
24 | * scaled DCT. Their original paper (Trans. IEICE E-71(11):1095) is in | ||
25 | * Japanese, but the algorithm is described in the Pennebaker & Mitchell | ||
26 | * JPEG textbook (see REFERENCES section in file README). The following code | ||
27 | * is based directly on figure 4-8 in P&M. | ||
28 | * While an 8-point DCT cannot be done in less than 11 multiplies, it is | ||
29 | * possible to arrange the computation so that many of the multiplies are | ||
30 | * simple scalings of the final outputs. These multiplies can then be | ||
31 | * folded into the multiplications or divisions by the JPEG quantization | ||
32 | * table entries. The AA&N method leaves only 5 multiplies and 29 adds | ||
33 | * to be done in the DCT itself. | ||
34 | * The primary disadvantage of this method is that with a fixed-point | ||
35 | * implementation, accuracy is lost due to imprecise representation of the | ||
36 | * scaled quantization values. However, that problem does not arise if | ||
37 | * we use floating point arithmetic. | ||
38 | */ | ||
39 | |||
40 | #define JPEG_INTERNALS | ||
41 | #include "jinclude.h" | ||
42 | #include "jpeglib.h" | ||
43 | #include "jdct.h" /* Private declarations for DCT subsystem */ | ||
44 | |||
45 | #ifdef DCT_FLOAT_SUPPORTED | ||
46 | |||
47 | |||
48 | /* | ||
49 | * This module is specialized to the case DCTSIZE = 8. | ||
50 | */ | ||
51 | |||
52 | #if DCTSIZE != 8 | ||
53 | Sorry, this code only copes with 8x8 DCTs. /* deliberate syntax err */ | ||
54 | #endif | ||
55 | |||
56 | |||
57 | /* Dequantize a coefficient by multiplying it by the multiplier-table | ||
58 | * entry; produce a float result. | ||
59 | */ | ||
60 | |||
61 | #define DEQUANTIZE(coef,quantval) (((FAST_FLOAT) (coef)) * (quantval)) | ||
62 | |||
63 | |||
64 | /* | ||
65 | * Perform dequantization and inverse DCT on one block of coefficients. | ||
66 | */ | ||
67 | |||
68 | GLOBAL(void) | ||
69 | jpeg_idct_float (j_decompress_ptr cinfo, jpeg_component_info * compptr, | ||
70 | JCOEFPTR coef_block, | ||
71 | JSAMPARRAY output_buf, JDIMENSION output_col) | ||
72 | { | ||
73 | FAST_FLOAT tmp0, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7; | ||
74 | FAST_FLOAT tmp10, tmp11, tmp12, tmp13; | ||
75 | FAST_FLOAT z5, z10, z11, z12, z13; | ||
76 | JCOEFPTR inptr; | ||
77 | FLOAT_MULT_TYPE * quantptr; | ||
78 | FAST_FLOAT * wsptr; | ||
79 | JSAMPROW outptr; | ||
80 | JSAMPLE *range_limit = cinfo->sample_range_limit; | ||
81 | int ctr; | ||
82 | FAST_FLOAT workspace[DCTSIZE2]; /* buffers data between passes */ | ||
83 | |||
84 | /* Pass 1: process columns from input, store into work array. */ | ||
85 | |||
86 | inptr = coef_block; | ||
87 | quantptr = (FLOAT_MULT_TYPE *) compptr->dct_table; | ||
88 | wsptr = workspace; | ||
89 | for (ctr = DCTSIZE; ctr > 0; ctr--) { | ||
90 | /* Due to quantization, we will usually find that many of the input | ||
91 | * coefficients are zero, especially the AC terms. We can exploit this | ||
92 | * by short-circuiting the IDCT calculation for any column in which all | ||
93 | * the AC terms are zero. In that case each output is equal to the | ||
94 | * DC coefficient (with scale factor as needed). | ||
95 | * With typical images and quantization tables, half or more of the | ||
96 | * column DCT calculations can be simplified this way. | ||
97 | */ | ||
98 | |||
99 | if (inptr[DCTSIZE*1] == 0 && inptr[DCTSIZE*2] == 0 && | ||
100 | inptr[DCTSIZE*3] == 0 && inptr[DCTSIZE*4] == 0 && | ||
101 | inptr[DCTSIZE*5] == 0 && inptr[DCTSIZE*6] == 0 && | ||
102 | inptr[DCTSIZE*7] == 0) { | ||
103 | /* AC terms all zero */ | ||
104 | FAST_FLOAT dcval = DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]); | ||
105 | |||
106 | wsptr[DCTSIZE*0] = dcval; | ||
107 | wsptr[DCTSIZE*1] = dcval; | ||
108 | wsptr[DCTSIZE*2] = dcval; | ||
109 | wsptr[DCTSIZE*3] = dcval; | ||
110 | wsptr[DCTSIZE*4] = dcval; | ||
111 | wsptr[DCTSIZE*5] = dcval; | ||
112 | wsptr[DCTSIZE*6] = dcval; | ||
113 | wsptr[DCTSIZE*7] = dcval; | ||
114 | |||
115 | inptr++; /* advance pointers to next column */ | ||
116 | quantptr++; | ||
117 | wsptr++; | ||
118 | continue; | ||
119 | } | ||
120 | |||
121 | /* Even part */ | ||
122 | |||
123 | tmp0 = DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]); | ||
124 | tmp1 = DEQUANTIZE(inptr[DCTSIZE*2], quantptr[DCTSIZE*2]); | ||
125 | tmp2 = DEQUANTIZE(inptr[DCTSIZE*4], quantptr[DCTSIZE*4]); | ||
126 | tmp3 = DEQUANTIZE(inptr[DCTSIZE*6], quantptr[DCTSIZE*6]); | ||
127 | |||
128 | tmp10 = tmp0 + tmp2; /* phase 3 */ | ||
129 | tmp11 = tmp0 - tmp2; | ||
130 | |||
131 | tmp13 = tmp1 + tmp3; /* phases 5-3 */ | ||
132 | tmp12 = (tmp1 - tmp3) * ((FAST_FLOAT) 1.414213562) - tmp13; /* 2*c4 */ | ||
133 | |||
134 | tmp0 = tmp10 + tmp13; /* phase 2 */ | ||
135 | tmp3 = tmp10 - tmp13; | ||
136 | tmp1 = tmp11 + tmp12; | ||
137 | tmp2 = tmp11 - tmp12; | ||
138 | |||
139 | /* Odd part */ | ||
140 | |||
141 | tmp4 = DEQUANTIZE(inptr[DCTSIZE*1], quantptr[DCTSIZE*1]); | ||
142 | tmp5 = DEQUANTIZE(inptr[DCTSIZE*3], quantptr[DCTSIZE*3]); | ||
143 | tmp6 = DEQUANTIZE(inptr[DCTSIZE*5], quantptr[DCTSIZE*5]); | ||
144 | tmp7 = DEQUANTIZE(inptr[DCTSIZE*7], quantptr[DCTSIZE*7]); | ||
145 | |||
146 | z13 = tmp6 + tmp5; /* phase 6 */ | ||
147 | z10 = tmp6 - tmp5; | ||
148 | z11 = tmp4 + tmp7; | ||
149 | z12 = tmp4 - tmp7; | ||
150 | |||
151 | tmp7 = z11 + z13; /* phase 5 */ | ||
152 | tmp11 = (z11 - z13) * ((FAST_FLOAT) 1.414213562); /* 2*c4 */ | ||
153 | |||
154 | z5 = (z10 + z12) * ((FAST_FLOAT) 1.847759065); /* 2*c2 */ | ||
155 | tmp10 = z5 - z12 * ((FAST_FLOAT) 1.082392200); /* 2*(c2-c6) */ | ||
156 | tmp12 = z5 - z10 * ((FAST_FLOAT) 2.613125930); /* 2*(c2+c6) */ | ||
157 | |||
158 | tmp6 = tmp12 - tmp7; /* phase 2 */ | ||
159 | tmp5 = tmp11 - tmp6; | ||
160 | tmp4 = tmp10 - tmp5; | ||
161 | |||
162 | wsptr[DCTSIZE*0] = tmp0 + tmp7; | ||
163 | wsptr[DCTSIZE*7] = tmp0 - tmp7; | ||
164 | wsptr[DCTSIZE*1] = tmp1 + tmp6; | ||
165 | wsptr[DCTSIZE*6] = tmp1 - tmp6; | ||
166 | wsptr[DCTSIZE*2] = tmp2 + tmp5; | ||
167 | wsptr[DCTSIZE*5] = tmp2 - tmp5; | ||
168 | wsptr[DCTSIZE*3] = tmp3 + tmp4; | ||
169 | wsptr[DCTSIZE*4] = tmp3 - tmp4; | ||
170 | |||
171 | inptr++; /* advance pointers to next column */ | ||
172 | quantptr++; | ||
173 | wsptr++; | ||
174 | } | ||
175 | |||
176 | /* Pass 2: process rows from work array, store into output array. */ | ||
177 | |||
178 | wsptr = workspace; | ||
179 | for (ctr = 0; ctr < DCTSIZE; ctr++) { | ||
180 | outptr = output_buf[ctr] + output_col; | ||
181 | /* Rows of zeroes can be exploited in the same way as we did with columns. | ||
182 | * However, the column calculation has created many nonzero AC terms, so | ||
183 | * the simplification applies less often (typically 5% to 10% of the time). | ||
184 | * And testing floats for zero is relatively expensive, so we don't bother. | ||
185 | */ | ||
186 | |||
187 | /* Even part */ | ||
188 | |||
189 | /* Apply signed->unsigned and prepare float->int conversion */ | ||
190 | z5 = wsptr[0] + ((FAST_FLOAT) CENTERJSAMPLE + (FAST_FLOAT) 0.5); | ||
191 | tmp10 = z5 + wsptr[4]; | ||
192 | tmp11 = z5 - wsptr[4]; | ||
193 | |||
194 | tmp13 = wsptr[2] + wsptr[6]; | ||
195 | tmp12 = (wsptr[2] - wsptr[6]) * ((FAST_FLOAT) 1.414213562) - tmp13; | ||
196 | |||
197 | tmp0 = tmp10 + tmp13; | ||
198 | tmp3 = tmp10 - tmp13; | ||
199 | tmp1 = tmp11 + tmp12; | ||
200 | tmp2 = tmp11 - tmp12; | ||
201 | |||
202 | /* Odd part */ | ||
203 | |||
204 | z13 = wsptr[5] + wsptr[3]; | ||
205 | z10 = wsptr[5] - wsptr[3]; | ||
206 | z11 = wsptr[1] + wsptr[7]; | ||
207 | z12 = wsptr[1] - wsptr[7]; | ||
208 | |||
209 | tmp7 = z11 + z13; | ||
210 | tmp11 = (z11 - z13) * ((FAST_FLOAT) 1.414213562); | ||
211 | |||
212 | z5 = (z10 + z12) * ((FAST_FLOAT) 1.847759065); /* 2*c2 */ | ||
213 | tmp10 = z5 - z12 * ((FAST_FLOAT) 1.082392200); /* 2*(c2-c6) */ | ||
214 | tmp12 = z5 - z10 * ((FAST_FLOAT) 2.613125930); /* 2*(c2+c6) */ | ||
215 | |||
216 | tmp6 = tmp12 - tmp7; | ||
217 | tmp5 = tmp11 - tmp6; | ||
218 | tmp4 = tmp10 - tmp5; | ||
219 | |||
220 | /* Final output stage: float->int conversion and range-limit */ | ||
221 | |||
222 | outptr[0] = range_limit[((int) (tmp0 + tmp7)) & RANGE_MASK]; | ||
223 | outptr[7] = range_limit[((int) (tmp0 - tmp7)) & RANGE_MASK]; | ||
224 | outptr[1] = range_limit[((int) (tmp1 + tmp6)) & RANGE_MASK]; | ||
225 | outptr[6] = range_limit[((int) (tmp1 - tmp6)) & RANGE_MASK]; | ||
226 | outptr[2] = range_limit[((int) (tmp2 + tmp5)) & RANGE_MASK]; | ||
227 | outptr[5] = range_limit[((int) (tmp2 - tmp5)) & RANGE_MASK]; | ||
228 | outptr[3] = range_limit[((int) (tmp3 + tmp4)) & RANGE_MASK]; | ||
229 | outptr[4] = range_limit[((int) (tmp3 - tmp4)) & RANGE_MASK]; | ||
230 | |||
231 | wsptr += DCTSIZE; /* advance pointer to next row */ | ||
232 | } | ||
233 | } | ||
234 | |||
235 | #endif /* DCT_FLOAT_SUPPORTED */ | ||