[Mesa-dev] [PATCH 3/8] i965/blorp: Compute sample number correctly for 8x MSAA.
Paul Berry
stereotype441 at gmail.com
Wed Jul 18 09:21:01 PDT 2012
When operating in persample dispatch mode, the blorp engine would
previously assume that subspan N always represented sample N (this is
correct assuming 4x MSAA and a 16-wide dispatch). In order to support
8x MSAA, we must compute which sample is associated with each subspan,
using the "Starting Sample Pair Index" field in the thread payload.
---
src/mesa/drivers/dri/i965/brw_blorp_blit.cpp | 55 +++++++++++++++++++------
1 files changed, 42 insertions(+), 13 deletions(-)
diff --git a/src/mesa/drivers/dri/i965/brw_blorp_blit.cpp b/src/mesa/drivers/dri/i965/brw_blorp_blit.cpp
index 940a293..833f2c5 100644
--- a/src/mesa/drivers/dri/i965/brw_blorp_blit.cpp
+++ b/src/mesa/drivers/dri/i965/brw_blorp_blit.cpp
@@ -815,19 +815,48 @@ brw_blorp_blit_program::compute_frag_coords()
brw_ADD(&func, Y, stride(suboffset(R1, 5), 2, 4, 0), brw_imm_v(0x11001100));
if (key->persample_msaa_dispatch) {
- /* The WM will be run in MSDISPMODE_PERSAMPLE with num_samples > 0.
- * Therefore, subspan 0 will represent sample 0, subspan 1 will
- * represent sample 1, and so on.
- *
- * So we need to populate S with the sequence (0, 0, 0, 0, 1, 1, 1, 1,
- * 2, 2, 2, 2, 3, 3, 3, 3). The easiest way to do this is to populate a
- * temporary variable with the sequence (0, 1, 2, 3), and then copy from
- * it using vstride=1, width=4, hstride=0.
- *
- * TODO: implement the necessary calculation for 8x multisampling.
- */
- brw_MOV(&func, t1, brw_imm_v(0x3210));
- brw_MOV(&func, S, stride(t1, 1, 4, 0));
+ switch (key->rt_samples) {
+ case 4:
+ /* The WM will be run in MSDISPMODE_PERSAMPLE with num_samples == 4.
+ * Therefore, subspan 0 will represent sample 0, subspan 1 will
+ * represent sample 1, and so on.
+ *
+ * So we need to populate S with the sequence (0, 0, 0, 0, 1, 1, 1,
+ * 1, 2, 2, 2, 2, 3, 3, 3, 3). The easiest way to do this is to
+ * populate a temporary variable with the sequence (0, 1, 2, 3), and
+ * then copy from it using vstride=1, width=4, hstride=0.
+ */
+ brw_MOV(&func, t1, brw_imm_v(0x3210));
+ brw_MOV(&func, S, stride(t1, 1, 4, 0));
+ break;
+ case 8: {
+ /* The WM will be run in MSDISPMODE_PERSAMPLE with num_samples == 8.
+ * Therefore, subspan 0 will represent sample N (where N is 0 or 4),
+ * subspan 1 will represent sample 1, and so on. We can find the
+ * value of N by looking at R0.0 bits 7:6 ("Starting Sample Pair
+ * Index") and multiplying by two (since samples are always delivered
+ * in pairs). That is, we compute 2*((R0.0 & 0xc0) >> 6) == (R0.0 &
+ * 0xc0) >> 5.
+ *
+ * Then we need to add N to the sequence (0, 0, 0, 0, 1, 1, 1, 1, 2,
+ * 2, 2, 2, 3, 3, 3, 3), which we compute by populating a temporary
+ * variable with the sequence (0, 1, 2, 3), and then reading from it
+ * using vstride=1, width=4, hstride=0.
+ */
+ struct brw_reg t1_ud1 = vec1(retype(t1, BRW_REGISTER_TYPE_UD));
+ struct brw_reg r0_ud1 = vec1(retype(R0, BRW_REGISTER_TYPE_UD));
+ brw_AND(&func, t1_ud1, r0_ud1, brw_imm_ud(0xc0));
+ brw_SHR(&func, t1_ud1, t1_ud1, brw_imm_ud(5));
+ brw_MOV(&func, t2, brw_imm_v(0x3210));
+ brw_ADD(&func, S, retype(t1_ud1, BRW_REGISTER_TYPE_UW),
+ stride(t2, 1, 4, 0));
+ break;
+ }
+ default:
+ assert(!"Unrecognized sample count in "
+ "brw_blorp_blit_program::compute_frag_coords()");
+ break;
+ }
s_is_zero = false;
} else {
/* Either the destination surface is single-sampled, or the WM will be
--
1.7.7.6
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