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
29
30/**
31 * 3DSTATE_MULTISAMPLE
32 */
33void
34gen6_emit_3dstate_multisample(struct brw_context *brw,
35                              unsigned num_samples)
36{
37   struct intel_context *intel = &brw->intel;
38
39   uint32_t number_of_multisamples = 0;
40   uint32_t sample_positions_3210 = 0;
41   uint32_t sample_positions_7654 = 0;
42
43   switch (num_samples) {
44   case 0:
45   case 1:
46      number_of_multisamples = MS_NUMSAMPLES_1;
47      break;
48   case 4:
49      number_of_multisamples = MS_NUMSAMPLES_4;
50      /* Sample positions:
51       *   2 6 a e
52       * 2   0
53       * 6       1
54       * a 2
55       * e     3
56       */
57      sample_positions_3210 = 0xae2ae662;
58      break;
59   case 8:
60      number_of_multisamples = MS_NUMSAMPLES_8;
61      /* Sample positions are based on a solution to the "8 queens" puzzle.
62       * Rationale: in a solution to the 8 queens puzzle, no two queens share
63       * a row, column, or diagonal.  This is a desirable property for samples
64       * in a multisampling pattern, because it ensures that the samples are
65       * relatively uniformly distributed through the pixel.
66       *
67       * There are several solutions to the 8 queens puzzle (see
68       * http://en.wikipedia.org/wiki/Eight_queens_puzzle).  This solution was
69       * chosen because it has a queen close to the center; this should
70       * improve the accuracy of centroid interpolation, since the hardware
71       * implements centroid interpolation by choosing the centermost sample
72       * that overlaps with the primitive being drawn.
73       *
74       * Note: from the Ivy Bridge PRM, Vol2 Part1 p304 (3DSTATE_MULTISAMPLE:
75       * Programming Notes):
76       *
77       *     "When programming the sample offsets (for NUMSAMPLES_4 or _8 and
78       *     MSRASTMODE_xxx_PATTERN), the order of the samples 0 to 3 (or 7
79       *     for 8X) must have monotonically increasing distance from the
80       *     pixel center. This is required to get the correct centroid
81       *     computation in the device."
82       *
83       * Sample positions:
84       *   1 3 5 7 9 b d f
85       * 1     5
86       * 3           2
87       * 5               6
88       * 7 4
89       * 9       0
90       * b             3
91       * d         1
92       * f   7
93       */
94      sample_positions_3210 = 0xdbb39d79;
95      sample_positions_7654 = 0x3ff55117;
96      break;
97   default:
98      assert(!"Unrecognized num_samples in gen6_emit_3dstate_multisample");
99      break;
100   }
101
102   int len = intel->gen >= 7 ? 4 : 3;
103   BEGIN_BATCH(len);
104   OUT_BATCH(_3DSTATE_MULTISAMPLE << 16 | (len - 2));
105   OUT_BATCH(MS_PIXEL_LOCATION_CENTER | number_of_multisamples);
106   OUT_BATCH(sample_positions_3210);
107   if (intel->gen >= 7)
108      OUT_BATCH(sample_positions_7654);
109   ADVANCE_BATCH();
110}
111
112
113/**
114 * 3DSTATE_SAMPLE_MASK
115 */
116void
117gen6_emit_3dstate_sample_mask(struct brw_context *brw,
118                              unsigned num_samples, float coverage,
119                              bool coverage_invert)
120{
121   struct intel_context *intel = &brw->intel;
122
123   BEGIN_BATCH(2);
124   OUT_BATCH(_3DSTATE_SAMPLE_MASK << 16 | (2 - 2));
125   if (num_samples > 1) {
126      int coverage_int = (int) (num_samples * coverage + 0.5);
127      uint32_t coverage_bits = (1 << coverage_int) - 1;
128      if (coverage_invert)
129         coverage_bits ^= (1 << num_samples) - 1;
130      OUT_BATCH(coverage_bits);
131   } else {
132      OUT_BATCH(1);
133   }
134   ADVANCE_BATCH();
135}
136
137
138static void upload_multisample_state(struct brw_context *brw)
139{
140   struct intel_context *intel = &brw->intel;
141   struct gl_context *ctx = &intel->ctx;
142   float coverage = 1.0;
143   float coverage_invert = false;
144
145   /* _NEW_BUFFERS */
146   unsigned num_samples = ctx->DrawBuffer->Visual.samples;
147
148   /* _NEW_MULTISAMPLE */
149   if (ctx->Multisample._Enabled && ctx->Multisample.SampleCoverage) {
150      coverage = ctx->Multisample.SampleCoverageValue;
151      coverage_invert = ctx->Multisample.SampleCoverageInvert;
152   }
153
154   /* 3DSTATE_MULTISAMPLE is nonpipelined. */
155   intel_emit_post_sync_nonzero_flush(intel);
156
157   gen6_emit_3dstate_multisample(brw, num_samples);
158   gen6_emit_3dstate_sample_mask(brw, num_samples, coverage, coverage_invert);
159}
160
161
162const struct brw_tracked_state gen6_multisample_state = {
163   .dirty = {
164      .mesa = _NEW_BUFFERS |
165              _NEW_MULTISAMPLE,
166      .brw = BRW_NEW_CONTEXT,
167      .cache = 0
168   },
169   .emit = upload_multisample_state
170};
171