1/*
2 * Copyright © 2012 Intel Corporation
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 DEALINGS
21 * IN THE SOFTWARE.
22 */
23
24#include "intel_batchbuffer.h"
25
26#include "brw_context.h"
27#include "brw_defines.h"
28#include "brw_multisample_state.h"
29#include "main/framebuffer.h"
30
31void
32gen6_get_sample_position(struct gl_context *ctx,
33                         struct gl_framebuffer *fb,
34                         GLuint index, GLfloat *result)
35{
36   uint8_t bits;
37
38   switch (_mesa_geometric_samples(fb)) {
39   case 1:
40      result[0] = result[1] = 0.5f;
41      return;
42   case 2:
43      bits = brw_multisample_positions_1x_2x >> (8 * index);
44      break;
45   case 4:
46      bits = brw_multisample_positions_4x >> (8 * index);
47      break;
48   case 8:
49      bits = brw_multisample_positions_8x[index >> 2] >> (8 * (index & 3));
50      break;
51   case 16:
52      bits = brw_multisample_positions_16x[index >> 2] >> (8 * (index & 3));
53      break;
54   default:
55      unreachable("Not implemented");
56   }
57
58   /* Convert from U0.4 back to a floating point coordinate. */
59   result[0] = ((bits >> 4) & 0xf) / 16.0f;
60   result[1] = (bits & 0xf) / 16.0f;
61}
62
63/**
64 * Sample index layout shows the numbering of slots in a rectangular
65 * grid of samples with in a pixel. Sample number layout shows the
66 * rectangular grid of samples roughly corresponding to the real sample
67 * locations with in a pixel. Sample number layout matches the sample
68 * index layout in case of 2X and 4x MSAA, but they are different in
69 * case of 8X MSAA.
70 *
71 * 8X MSAA sample index layout    8x MSAA sample number layout
72 *           ---------                      ---------
73 *           | 0 | 1 |                      | 1 | 0 |
74 *           ---------                      ---------
75 *
76 * 4X MSAA sample index / number layout
77 *           ---------
78 *           | 0 | 1 |
79 *           ---------
80 *           | 2 | 3 |
81 *           ---------
82 *
83 * 8X MSAA sample index layout    8x MSAA sample number layout
84 *           ---------                      ---------
85 *           | 0 | 1 |                      | 5 | 2 |
86 *           ---------                      ---------
87 *           | 2 | 3 |                      | 4 | 6 |
88 *           ---------                      ---------
89 *           | 4 | 5 |                      | 0 | 3 |
90 *           ---------                      ---------
91 *           | 6 | 7 |                      | 7 | 1 |
92 *           ---------                      ---------
93 *
94 * 16X MSAA sample index layout  16x MSAA sample number layout
95 *         -----------------            -----------------
96 *         | 0 | 1 | 2 | 3 |            |15 |10 | 9 | 7 |
97 *         -----------------            -----------------
98 *         | 4 | 5 | 6 | 7 |            | 4 | 1 | 3 |13 |
99 *         -----------------            -----------------
100 *         | 8 | 9 |10 |11 |            |12 | 2 | 0 | 6 |
101 *         -----------------            -----------------
102 *         |12 |13 |14 |15 |            |11 | 8 | 5 |14 |
103 *         -----------------            -----------------
104 *
105 * A sample map is used to map sample indices to sample numbers.
106 */
107void
108gen6_set_sample_maps(struct gl_context *ctx)
109{
110   uint8_t map_2x[2] = {1, 0};
111   uint8_t map_4x[4] = {0, 1, 2, 3};
112   uint8_t map_8x[8] = {3, 7, 5, 0, 1, 2, 4, 6};
113   uint8_t map_16x[16] = { 15, 10, 9, 7, 4, 1, 3, 13,
114                           12, 2, 0, 6, 11, 8, 5, 14 };
115
116   memcpy(ctx->Const.SampleMap2x, map_2x, sizeof(map_2x));
117   memcpy(ctx->Const.SampleMap4x, map_4x, sizeof(map_4x));
118   memcpy(ctx->Const.SampleMap8x, map_8x, sizeof(map_8x));
119   memcpy(ctx->Const.SampleMap16x, map_16x, sizeof(map_16x));
120}
121