From da47dfaacfae1134b238af9083a7f3d413c6cbbe Mon Sep 17 00:00:00 2001
From: goldislead <69987043+goldislead@users.noreply.github.com>
Date: Sun, 2 Aug 2026 03:37:31 -0700
Subject: [PATCH] [GPU/DXBC] Fix signed round bias breaking memexport

Write the bias into round_bias_temp as intended in both packed 8/16/32bpp path and 16_16_16_16.

The copysign rounding bias was targeted the eM register, and destroying the scaled value, then added round_bias_temp, which nothing had written.
---
 src/xenia/gpu/dxbc_shader_translator_memexport.cc | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/src/xenia/gpu/dxbc_shader_translator_memexport.cc b/src/xenia/gpu/dxbc_shader_translator_memexport.cc
index d3d8ec7c6..f24afa337 100644
--- a/src/xenia/gpu/dxbc_shader_translator_memexport.cc
+++ b/src/xenia/gpu/dxbc_shader_translator_memexport.cc
@@ -195,8 +195,9 @@ void DxbcShaderTranslator::ExportToMemory(uint8_t export_eM) {
         while (xe::bit_scan_forward(eM_remaining, &eM_index)) {
           eM_remaining &= ~(uint8_t(1) << eM_index);
           uint32_t eM = system_temps_memexport_data_[eM_index];
-          a_.OpBFI(dxbc::Dest::R(eM, components), dxbc::Src::LU(31),
-                   dxbc::Src::LU(0), dxbc::Src::LF(0.5f), dxbc::Src::R(eM));
+          a_.OpBFI(dxbc::Dest::R(round_bias_temp, components),
+                   dxbc::Src::LU(31), dxbc::Src::LU(0), dxbc::Src::LF(0.5f),
+                   dxbc::Src::R(eM));
           a_.OpAdd(dxbc::Dest::R(eM, components), dxbc::Src::R(eM),
                    dxbc::Src::R(round_bias_temp));
           a_.OpFToI(dxbc::Dest::R(eM, components), dxbc::Src::R(eM));
@@ -421,8 +422,8 @@ void DxbcShaderTranslator::ExportToMemory(uint8_t export_eM) {
         while (xe::bit_scan_forward(eM_remaining, &eM_index)) {
           eM_remaining &= ~(uint8_t(1) << eM_index);
           uint32_t eM = system_temps_memexport_data_[eM_index];
-          a_.OpBFI(dxbc::Dest::R(eM), dxbc::Src::LU(31), dxbc::Src::LU(0),
-                   dxbc::Src::LF(0.5f), dxbc::Src::R(eM));
+          a_.OpBFI(dxbc::Dest::R(round_bias_temp), dxbc::Src::LU(31),
+                   dxbc::Src::LU(0), dxbc::Src::LF(0.5f), dxbc::Src::R(eM));
           a_.OpAdd(dxbc::Dest::R(eM), dxbc::Src::R(eM),
                    dxbc::Src::R(round_bias_temp));
           a_.OpFToI(dxbc::Dest::R(eM), dxbc::Src::R(eM));