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 "brw_batch.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
32gfx6_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