From d41287c3202ef6dc352e0e2ee1e7c7e280f12fc4 Mon Sep 17 00:00:00 2001
From: joevt <joevt@shaw.ca>
Date: Wed, 27 Nov 2024 04:31:36 -0800
Subject: [PATCH] ppcfpopcodes: fneg fix.

fneg inverts the sign bit regardless of nan status.
---
 cpu/ppc/ppcfpopcodes.cpp | 15 ++++-----------
 cpu/ppc/ppcmacros.h      |  5 ++++-
 2 files changed, 8 insertions(+), 12 deletions(-)

diff --git a/cpu/ppc/ppcfpopcodes.cpp b/cpu/ppc/ppcfpopcodes.cpp
index 5b15677..172a93c 100644
--- a/cpu/ppc/ppcfpopcodes.cpp
+++ b/cpu/ppc/ppcfpopcodes.cpp
@@ -816,18 +816,11 @@ template <field_rc rec>
 void dppc_interpreter::ppc_fneg() {
     ppc_grab_regsfpdb(ppc_cur_instruction);
 
-    double ppc_dblresult64_d = -(GET_FPR(reg_b));
+    uint64_t ppc_result64_d = FPR_INT(reg_b) ^ 0x8000000000000000U;
 
-    if (std::isnan(GET_FPR(reg_b))) {
-        ppc_dblresult64_d = std::numeric_limits<double>::quiet_NaN();
-    } 
-    
-    if (snan_single_check(reg_b)) {
-        uint64_t qnan = 0x7FFC000000000000;
-        ppc_store_fpresult_int(reg_d, qnan);
-    } else {
-        ppc_store_fpresult_flt(reg_d, ppc_dblresult64_d);
-    }
+    ppc_store_fpresult_int(reg_d, ppc_result64_d);
+
+    snan_single_check(reg_d);
 
     if (rec)
         ppc_update_cr1();
diff --git a/cpu/ppc/ppcmacros.h b/cpu/ppc/ppcmacros.h
index 4417926..25c25c2 100644
--- a/cpu/ppc/ppcmacros.h
+++ b/cpu/ppc/ppcmacros.h
@@ -150,9 +150,12 @@ along with this program.  If not, see <https://www.gnu.org/licenses/>.
         int reg_d = (opcode >> 21) & 31; \
         int reg_b = (opcode >> 11) & 31;
 
-#define GET_FPR(reg)                                                                               \
+#define GET_FPR(reg) \
     ppc_state.fpr[(reg)].dbl64_r 
 
+#define FPR_INT(reg)\
+    ppc_state.fpr[reg].int64_r
+
 #define ppc_grab_regsfpdiab(opcode) \
         int reg_d          = (opcode >> 21) & 31; \
         int reg_a          = (opcode >> 16) & 31; \