r300g: move ZTOP to separate file

Ideally, HiZ should go in r300_hyperz.c next to ZTOP.

1 files changed, 108 insertions, 0 deletions

diff --git a/src/gallium/drivers/r300/r300_hyperz.c b/src/gallium/drivers/r300/r300_hyperz.c
new file mode 100644
index 0000000000..b41b6b1508
--- /dev/null
+++ b/src/gallium/drivers/r300/r300_hyperz.c
@@ -0,0 +1,108 @@
+/*
+ * 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_hyperz.h"
+#include "r300_context.h"
+#include "r300_reg.h"
+#include "r300_fs.h"
+
+/*****************************************************************************/
+/* The ZTOP state                                                            */
+/*****************************************************************************/
+
+static boolean r300_dsa_writes_depth_stencil(struct r300_dsa_state* dsa)
+{
+    /* We are interested only in the cases when a new depth or stencil value
+     * can be written and changed. */
+
+    /* We might optionally check for [Z func: never] and inspect the stencil
+     * state in a similar fashion, but it's not terribly important. */
+    return (dsa->z_buffer_control & R300_Z_WRITE_ENABLE) ||
+           (dsa->stencil_ref_mask & R300_STENCILWRITEMASK_MASK) ||
+           ((dsa->z_buffer_control & R500_STENCIL_REFMASK_FRONT_BACK) &&
+            (dsa->stencil_ref_bf & R300_STENCILWRITEMASK_MASK));
+}
+
+static boolean r300_dsa_alpha_test_enabled(struct r300_dsa_state* dsa)
+{
+    /* We are interested only in the cases when alpha testing can kill
+     * a fragment. */
+    uint32_t af = dsa->alpha_function;
+
+    return (af & R300_FG_ALPHA_FUNC_ENABLE) &&
+           (af & R300_FG_ALPHA_FUNC_ALWAYS) != R300_FG_ALPHA_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;
+
+    /* 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;
+    }
+
+    r300->ztop_state.dirty = TRUE;
+}
+
+void r300_update_hyperz_state(struct r300_context* r300)
+{
+    r300_update_ztop(r300);
+}