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      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 
     31 void
     32 gen6_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  * 2X MSAA sample index / number layout
     72  *           ---------
     73  *           | 0 | 1 |
     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  */
    107 void
    108 gen6_set_sample_maps(struct gl_context *ctx)
    109 {
    110    uint8_t map_2x[2] = {0, 1};
    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