1 /*
2 * Copyright (C) 2011 LunarG, Inc.
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice (including the next
12 * paragraph) shall be included in all copies or substantial portions of the
13 * Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
21 * DEALINGS IN THE SOFTWARE.
22 */
23
24 /*
25 * Included by texcompress_etc1 and gallium to define ETC1 decoding routines.
26 */
27
TAG(etc1_block)28 struct TAG(etc1_block) {
29 uint32_t pixel_indices;
30 int flipped;
31 const int *modifier_tables[2];
32 UINT8_TYPE base_colors[2][3];
33 };
34
35 static UINT8_TYPE
TAG(etc1_base_color_diff_hi)36 TAG(etc1_base_color_diff_hi)(UINT8_TYPE in)
37 {
38 return (in & 0xf8) | (in >> 5);
39 }
40
41 static UINT8_TYPE
TAG(etc1_base_color_diff_lo)42 TAG(etc1_base_color_diff_lo)(UINT8_TYPE in)
43 {
44 static const int lookup[8] = { 0, 1, 2, 3, -4, -3, -2, -1 };
45
46 in = (in >> 3) + lookup[in & 0x7];
47
48 return (in << 3) | (in >> 2);
49 }
50
51 static UINT8_TYPE
TAG(etc1_base_color_ind_hi)52 TAG(etc1_base_color_ind_hi)(UINT8_TYPE in)
53 {
54 return (in & 0xf0) | ((in & 0xf0) >> 4);
55 }
56
57 static UINT8_TYPE
TAG(etc1_base_color_ind_lo)58 TAG(etc1_base_color_ind_lo)(UINT8_TYPE in)
59 {
60 return ((in & 0xf) << 4) | (in & 0xf);
61 }
62
63 static UINT8_TYPE
TAG(etc1_clamp)64 TAG(etc1_clamp)(UINT8_TYPE base, int modifier)
65 {
66 int tmp = (int) base + modifier;
67
68 /* CLAMP(tmp, 0, 255) */
69 return (UINT8_TYPE) ((tmp < 0) ? 0 : ((tmp > 255) ? 255 : tmp));
70 }
71
72 static const int TAG(etc1_modifier_tables)[8][4] = {
73 { 2, 8, -2, -8},
74 { 5, 17, -5, -17},
75 { 9, 29, -9, -29},
76 { 13, 42, -13, -42},
77 { 18, 60, -18, -60},
78 { 24, 80, -24, -80},
79 { 33, 106, -33, -106},
80 { 47, 183, -47, -183}
81 };
82
83 static void
TAG(etc1_parse_block)84 TAG(etc1_parse_block)(struct TAG(etc1_block) *block, const UINT8_TYPE *src)
85 {
86 if (src[3] & 0x2) {
87 /* differential mode */
88 block->base_colors[0][0] = (int) TAG(etc1_base_color_diff_hi)(src[0]);
89 block->base_colors[1][0] = (int) TAG(etc1_base_color_diff_lo)(src[0]);
90 block->base_colors[0][1] = (int) TAG(etc1_base_color_diff_hi)(src[1]);
91 block->base_colors[1][1] = (int) TAG(etc1_base_color_diff_lo)(src[1]);
92 block->base_colors[0][2] = (int) TAG(etc1_base_color_diff_hi)(src[2]);
93 block->base_colors[1][2] = (int) TAG(etc1_base_color_diff_lo)(src[2]);
94 }
95 else {
96 /* individual mode */
97 block->base_colors[0][0] = (int) TAG(etc1_base_color_ind_hi)(src[0]);
98 block->base_colors[1][0] = (int) TAG(etc1_base_color_ind_lo)(src[0]);
99 block->base_colors[0][1] = (int) TAG(etc1_base_color_ind_hi)(src[1]);
100 block->base_colors[1][1] = (int) TAG(etc1_base_color_ind_lo)(src[1]);
101 block->base_colors[0][2] = (int) TAG(etc1_base_color_ind_hi)(src[2]);
102 block->base_colors[1][2] = (int) TAG(etc1_base_color_ind_lo)(src[2]);
103 }
104
105 /* pick modifier tables */
106 block->modifier_tables[0] = TAG(etc1_modifier_tables)[(src[3] >> 5) & 0x7];
107 block->modifier_tables[1] = TAG(etc1_modifier_tables)[(src[3] >> 2) & 0x7];
108
109 block->flipped = (src[3] & 0x1);
110
111 block->pixel_indices =
112 (src[4] << 24) | (src[5] << 16) | (src[6] << 8) | src[7];
113 }
114
115 static void
TAG(etc1_fetch_texel)116 TAG(etc1_fetch_texel)(const struct TAG(etc1_block) *block,
117 int x, int y, UINT8_TYPE *dst)
118 {
119 const UINT8_TYPE *base_color;
120 int modifier, bit, idx, blk;
121
122 /* get pixel index */
123 bit = y + x * 4;
124 idx = ((block->pixel_indices >> (15 + bit)) & 0x2) |
125 ((block->pixel_indices >> (bit)) & 0x1);
126
127 /* get subblock */
128 blk = (block->flipped) ? (y >= 2) : (x >= 2);
129
130 base_color = block->base_colors[blk];
131 modifier = block->modifier_tables[blk][idx];
132
133 dst[0] = TAG(etc1_clamp)(base_color[0], modifier);
134 dst[1] = TAG(etc1_clamp)(base_color[1], modifier);
135 dst[2] = TAG(etc1_clamp)(base_color[2], modifier);
136 }
137
138 static void
etc1_unpack_rgba8888(uint8_t * dst_row,unsigned dst_stride,const uint8_t * src_row,unsigned src_stride,unsigned width,unsigned height)139 etc1_unpack_rgba8888(uint8_t *dst_row,
140 unsigned dst_stride,
141 const uint8_t *src_row,
142 unsigned src_stride,
143 unsigned width,
144 unsigned height)
145 {
146 const unsigned bw = 4, bh = 4, bs = 8, comps = 4;
147 struct etc1_block block;
148 unsigned x, y, i, j;
149
150 for (y = 0; y < height; y += bh) {
151 const uint8_t *src = src_row;
152
153 for (x = 0; x < width; x+= bw) {
154 etc1_parse_block(&block, src);
155
156 for (j = 0; j < MIN2(bh, height - y); j++) {
157 uint8_t *dst = dst_row + (y + j) * dst_stride + x * comps;
158 for (i = 0; i < MIN2(bw, width - x); i++) {
159 etc1_fetch_texel(&block, i, j, dst);
160 dst[3] = 255;
161 dst += comps;
162 }
163 }
164
165 src += bs;
166 }
167
168 src_row += src_stride;
169 }
170 }
171