text: /*
   * Copyright 2008 Corbin Simpson <MostAwesomeDude@gmail.com>
   * Copyright 2009 Marek Olšák <maraeo@gmail.com>
   *
   * Permission is hereby granted, free of charge, to any person obtaining a
   * copy of this software and associated documentation files (the "Software"),
   * to deal in the Software without restriction, including without limitation
   * on the rights to use, copy, modify, merge, publish, distribute, sub
   * license, and/or sell copies of the Software, and to permit persons to whom
   * the Software is furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice (including the next
   * paragraph) shall be included in all copies or substantial portions of the
   * Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
   * THE AUTHOR(S) AND/OR THEIR SUPPLIERS BE LIABLE FOR ANY CLAIM,
   * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
   * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
   * USE OR OTHER DEALINGS IN THE SOFTWARE. */
  
  #include "r300_context.h"
  #include "r300_reg.h"
  #include "r300_fs.h"
  
  #include "util/u_format.h"
  #include "util/u_mm.h"
  
  /*
    HiZ rules - taken from various docs 
     1. HiZ only works on depth values
     2. Cannot HiZ if stencil fail or zfail is !KEEP
     3. on R300/400, HiZ is disabled if depth test is EQUAL
     4. comparison changes without clears usually mean disabling HiZ
  */
  /*****************************************************************************/
  /* The HyperZ setup                                                          */
  /*****************************************************************************/
  
  static enum r300_hiz_func r300_get_hiz_func(struct r300_context *r300)
  {
      struct r300_dsa_state *dsa = r300->dsa_state.state;
  
      switch (dsa->dsa.depth.func) {
      case PIPE_FUNC_NEVER:
      case PIPE_FUNC_EQUAL:
      case PIPE_FUNC_NOTEQUAL:
      case PIPE_FUNC_ALWAYS:
      default:
          /* Guess MAX for uncertain cases. */
      case PIPE_FUNC_LESS:
      case PIPE_FUNC_LEQUAL:
          return HIZ_FUNC_MAX;
  
      case PIPE_FUNC_GREATER:
      case PIPE_FUNC_GEQUAL:
          return HIZ_FUNC_MIN;
      }
  }
  
  /* Return what's used for the depth test (either minimum or maximum). */
  static unsigned r300_get_sc_hz_max(struct r300_context *r300)
  {
      struct r300_dsa_state *dsa = r300->dsa_state.state;
      unsigned func = dsa->dsa.depth.func;
  
      return func >= PIPE_FUNC_GREATER ? R300_SC_HYPERZ_MAX : R300_SC_HYPERZ_MIN;
  }
  
  static boolean r300_is_hiz_func_valid(struct r300_context *r300)
  {
      struct r300_dsa_state *dsa = r300->dsa_state.state;
      unsigned func = dsa->dsa.depth.func;
  
      if (r300->hiz_func == HIZ_FUNC_NONE)
          return TRUE;
  
      /* func1 is less/lessthan */
      if (r300->hiz_func == HIZ_FUNC_MAX &&
          (func == PIPE_FUNC_GEQUAL || func == PIPE_FUNC_GREATER))
          return FALSE;
  
      /* func1 is greater/greaterthan */
      if (r300->hiz_func == HIZ_FUNC_MIN &&
          (func == PIPE_FUNC_LESS   || func == PIPE_FUNC_LEQUAL))
          return FALSE;
  
      return TRUE;
  }
  
  static boolean r300_dsa_stencil_op_not_keep(struct pipe_stencil_state *s)
  {
      return s->enabled && (s->fail_op != PIPE_STENCIL_OP_KEEP ||
                            s->zfail_op != PIPE_STENCIL_OP_KEEP);
  }
  
  static boolean r300_hiz_allowed(struct r300_context *r300)
  {
      struct r300_dsa_state *dsa = r300->dsa_state.state;
      struct r300_screen *r300screen = r300->screen;
  
      if (r300_fragment_shader_writes_depth(r300_fs(r300)))
          return FALSE;
  
      if (r300->query_current)
          return FALSE;
  
      /* If the depth function is inverted, HiZ must be disabled. */
      if (!r300_is_hiz_func_valid(r300))
          return FALSE;
  
      /* if stencil fail/zfail op is not KEEP */
      if (r300_dsa_stencil_op_not_keep(&dsa->dsa.stencil[0]) ||
          r300_dsa_stencil_op_not_keep(&dsa->dsa.stencil[1]))
          return FALSE;
  
      if (dsa->dsa.depth.enabled) {
          /* if depth func is EQUAL pre-r500 */
          if (dsa->dsa.depth.func == PIPE_FUNC_EQUAL && !r300screen->caps.is_r500)
              return FALSE;
  
          /* if depth func is NOTEQUAL */
          if (dsa->dsa.depth.func == PIPE_FUNC_NOTEQUAL)
              return FALSE;
      }
      return TRUE;
  }
  
  static void r300_update_hyperz(struct r300_context* r300)
  {
      struct r300_hyperz_state *z =
          (struct r300_hyperz_state*)r300->hyperz_state.state;
      struct pipe_framebuffer_state *fb =
          (struct pipe_framebuffer_state*)r300->fb_state.state;
      struct r300_dsa_state *dsa = r300->dsa_state.state;
      struct r300_resource *zstex =
              fb->zsbuf ? r300_resource(fb->zsbuf->texture) : NULL;
  
      z->gb_z_peq_config = 0;
      z->zb_bw_cntl = 0;
      z->sc_hyperz = R300_SC_HYPERZ_ADJ_2;
      z->flush = 0;
  
      if (r300->cbzb_clear) {
          z->zb_bw_cntl |= R300_ZB_CB_CLEAR_CACHE_LINE_WRITE_ONLY;
          return;
      }
  
      if (!zstex || !r300->hyperz_enabled)
          return;
  
      /* Set the size of ZMASK tiles. */
      if (zstex->tex.zcomp8x8[fb->zsbuf->u.tex.level]) {
          z->gb_z_peq_config |= R300_GB_Z_PEQ_CONFIG_Z_PEQ_SIZE_8_8;
      }
  
      /* R500-specific features and optimizations. */
      if (r300->screen->caps.is_r500) {
          z->zb_bw_cntl |= R500_PEQ_PACKING_ENABLE |
                           R500_COVERED_PTR_MASKING_ENABLE;
      }
  
      /* Setup decompression if needed. No other HyperZ setting is required. */
      if (r300->zmask_decompress) {
          z->zb_bw_cntl |= R300_FAST_FILL_ENABLE |
                           R300_RD_COMP_ENABLE;
          return;
      }
  
      /* Do not set anything if depth and stencil tests are off. */
      if (!dsa->dsa.depth.enabled &&
          !dsa->dsa.stencil[0].enabled &&
          !dsa->dsa.stencil[1].enabled) {
          assert(!dsa->dsa.depth.writemask);
          return;
      }
  
      /* Zbuffer compression. */
      if (r300->zmask_in_use && !r300->locked_zbuffer) {
          z->zb_bw_cntl |= R300_FAST_FILL_ENABLE |
                           R300_RD_COMP_ENABLE |
                           R300_WR_COMP_ENABLE;
      }
  
      /* HiZ. */
      if (r300->hiz_in_use && !r300->locked_zbuffer) {
          /* HiZ cannot be used under some circumstances. */
          if (!r300_hiz_allowed(r300)) {
              /* If writemask is disabled, the HiZ memory will not be changed,
               * so we can keep its content for later. */
              if (dsa->dsa.depth.writemask) {
                  r300->hiz_in_use = FALSE;
              }
              return;
          }
          DBG(r300, DBG_HYPERZ, "r300: Z-func: %i\n", dsa->dsa.depth.func);
  
          /* Set the HiZ function if needed. */
          if (r300->hiz_func == HIZ_FUNC_NONE) {
              r300->hiz_func = r300_get_hiz_func(r300);
          }
  
          /* Setup the HiZ bits. */
          z->zb_bw_cntl |= R300_HIZ_ENABLE |
                  (r300->hiz_func == HIZ_FUNC_MIN ? R300_HIZ_MIN : R300_HIZ_MAX);
  
          z->sc_hyperz |= R300_SC_HYPERZ_ENABLE |
                          r300_get_sc_hz_max(r300);
  
          if (r300->screen->caps.is_r500) {
              z->zb_bw_cntl |= R500_HIZ_EQUAL_REJECT_ENABLE;
          }
      }
  }
  
  /*****************************************************************************/
  /* The ZTOP state                                                            */
  /*****************************************************************************/
  
  static boolean r300_dsa_writes_stencil(
          struct pipe_stencil_state *s)
  {
      return s->enabled && s->writemask &&
             (s->fail_op  != PIPE_STENCIL_OP_KEEP ||
              s->zfail_op != PIPE_STENCIL_OP_KEEP ||
              s->zpass_op != PIPE_STENCIL_OP_KEEP);
  }
  
  static boolean r300_dsa_writes_depth_stencil(
          struct pipe_depth_stencil_alpha_state *dsa)
  {
      /* We are interested only in the cases when a depth or stencil value
       * can be changed. */
  
      if (dsa->depth.enabled && dsa->depth.writemask &&
          dsa->depth.func != PIPE_FUNC_NEVER)
          return TRUE;
  
      if (r300_dsa_writes_stencil(&dsa->stencil[0]) ||
          r300_dsa_writes_stencil(&dsa->stencil[1]))
          return TRUE;
  
      return FALSE;
  }
  
  static boolean r300_dsa_alpha_test_enabled(
          struct pipe_depth_stencil_alpha_state *dsa)
  {
      /* We are interested only in the cases when alpha testing can kill
       * a fragment. */
  
      return dsa->alpha.enabled && dsa->alpha.func != PIPE_FUNC_ALWAYS;
  }
  
  static void r300_update_ztop(struct r300_context* r300)
  {
      struct r300_ztop_state* ztop_state =
          (struct r300_ztop_state*)r300->ztop_state.state;
      uint32_t old_ztop = ztop_state->z_buffer_top;
  
      /* This is important enough that I felt it warranted a comment.
       *
       * According to the docs, these are the conditions where ZTOP must be
       * disabled:
       * 1) Alpha testing enabled
       * 2) Texture kill instructions in fragment shader
       * 3) Chroma key culling enabled
       * 4) W-buffering enabled
       *
       * The docs claim that for the first three cases, if no ZS writes happen,
       * then ZTOP can be used.
       *
       * (3) will never apply since we do not support chroma-keyed operations.
       * (4) will need to be re-examined (and this comment updated) if/when
       * Hyper-Z becomes supported.
       *
       * Additionally, the following conditions require disabled ZTOP:
       * 5) Depth writes in fragment shader
       * 6) Outstanding occlusion queries
       *
       * This register causes stalls all the way from SC to CB when changed,
       * but it is buffered on-chip so it does not hurt to write it if it has
       * not changed.
       *
       * ~C.
       */
  
      /* ZS writes */
      if (r300_dsa_writes_depth_stencil(r300->dsa_state.state) &&
             (r300_dsa_alpha_test_enabled(r300->dsa_state.state) ||  /* (1) */
              r300_fs(r300)->shader->info.uses_kill)) {              /* (2) */
          ztop_state->z_buffer_top = R300_ZTOP_DISABLE;
      } else if (r300_fragment_shader_writes_depth(r300_fs(r300))) { /* (5) */
          ztop_state->z_buffer_top = R300_ZTOP_DISABLE;
      } else if (r300->query_current) {                              /* (6) */
          ztop_state->z_buffer_top = R300_ZTOP_DISABLE;
      } else {
          ztop_state->z_buffer_top = R300_ZTOP_ENABLE;
      }
      if (ztop_state->z_buffer_top != old_ztop)
          r300_mark_atom_dirty(r300, &r300->ztop_state);
  }
  
  void r300_update_hyperz_state(struct r300_context* r300)
  {
      r300_update_ztop(r300);
  
      if (r300->hyperz_state.dirty) {
          r300_update_hyperz(r300);
      }
  }
  