From 11b588c6bb5e20d66cab19233676d6888ae3e6a7 Mon Sep 17 00:00:00 2001
From: OBattler <oubattler@gmail.com>
Date: Sat, 14 Dec 2024 00:59:52 +0100
Subject: [PATCH] Fix FPU reporting, fixes #5033.

---
 src/cpu/x86_ops_fpu.h      | 18 ++++--------------
 src/cpu/x86_ops_fpu_2386.h |  9 ++-------
 src/cpu/x87.c              |  5 ++++-
 src/cpu/x87.h              |  8 +++-----
 src/cpu/x87_ops.h          |  5 ++++-
 5 files changed, 17 insertions(+), 28 deletions(-)

diff --git a/src/cpu/x86_ops_fpu.h b/src/cpu/x86_ops_fpu.h
index 9ea04b447..11f603c19 100644
--- a/src/cpu/x86_ops_fpu.h
+++ b/src/cpu/x86_ops_fpu.h
@@ -4,7 +4,6 @@
 static int
 opESCAPE_d8_a16(uint32_t fetchdat)
 {
-    //pclog("D8 A16: fetchdat=%02x.\n", (fetchdat >> 3) & 0x1f);
     return x86_opcodes_d8_a16[(fetchdat >> 3) & 0x1f](fetchdat);
 }
 static int
@@ -16,7 +15,6 @@ opESCAPE_d8_a32(uint32_t fetchdat)
 static int
 opESCAPE_d9_a16(uint32_t fetchdat)
 {
-    //pclog("D9 A16: fetchdat=%02x.\n", fetchdat & 0xff);
     return x86_opcodes_d9_a16[fetchdat & 0xff](fetchdat);
 }
 static int
@@ -28,7 +26,6 @@ opESCAPE_d9_a32(uint32_t fetchdat)
 static int
 opESCAPE_da_a16(uint32_t fetchdat)
 {
-    //pclog("DA A16: fetchdat=%02x.\n", fetchdat & 0xff);
     return x86_opcodes_da_a16[fetchdat & 0xff](fetchdat);
 }
 static int
@@ -40,7 +37,6 @@ opESCAPE_da_a32(uint32_t fetchdat)
 static int
 opESCAPE_db_a16(uint32_t fetchdat)
 {
-    //pclog("DB A16: fetchdat=%02x.\n", fetchdat & 0xff);
     return x86_opcodes_db_a16[fetchdat & 0xff](fetchdat);
 }
 static int
@@ -52,7 +48,6 @@ opESCAPE_db_a32(uint32_t fetchdat)
 static int
 opESCAPE_dc_a16(uint32_t fetchdat)
 {
-    //pclog("DC A16: fetchdat=%02x.\n", (fetchdat >> 3) & 0x1f);
     return x86_opcodes_dc_a16[(fetchdat >> 3) & 0x1f](fetchdat);
 }
 static int
@@ -64,7 +59,6 @@ opESCAPE_dc_a32(uint32_t fetchdat)
 static int
 opESCAPE_dd_a16(uint32_t fetchdat)
 {
-    //pclog("DD A16: fetchdat=%02x.\n", fetchdat & 0xff);
     return x86_opcodes_dd_a16[fetchdat & 0xff](fetchdat);
 }
 static int
@@ -76,7 +70,6 @@ opESCAPE_dd_a32(uint32_t fetchdat)
 static int
 opESCAPE_de_a16(uint32_t fetchdat)
 {
-    //pclog("DE A16: fetchdat=%02x.\n", fetchdat & 0xff);
     return x86_opcodes_de_a16[fetchdat & 0xff](fetchdat);
 }
 static int
@@ -88,7 +81,6 @@ opESCAPE_de_a32(uint32_t fetchdat)
 static int
 opESCAPE_df_a16(uint32_t fetchdat)
 {
-    //pclog("DF A16: fetchdat=%02x.\n", fetchdat & 0xff);
     return x86_opcodes_df_a16[fetchdat & 0xff](fetchdat);
 }
 static int
@@ -105,15 +97,13 @@ opWAIT(uint32_t fetchdat)
         return 1;
     }
 
-#if 0
-    if (!cpu_use_dynarec && fpu_softfloat) {
-#endif
     if (fpu_softfloat) {
         if (fpu_state.swd & FPU_SW_Summary) {
-            if (cr0 & 0x20) {
+            if (is486 && (cr0 & 0x20))
                 x86_int(16);
-                return 1;
-            }
+            else
+                picint(1 << 13);
+            return 1;
         }
     }
     CLOCK_CYCLES(4);
diff --git a/src/cpu/x86_ops_fpu_2386.h b/src/cpu/x86_ops_fpu_2386.h
index 52c24d995..d8996d2e1 100644
--- a/src/cpu/x86_ops_fpu_2386.h
+++ b/src/cpu/x86_ops_fpu_2386.h
@@ -97,15 +97,10 @@ opWAIT(uint32_t fetchdat)
         return 1;
     }
 
-#if 0
-    if (!cpu_use_dynarec && fpu_softfloat) {
-#endif
     if (fpu_softfloat) {
         if (fpu_state.swd & FPU_SW_Summary) {
-            if (cr0 & 0x20) {
-                x86_int(16);
-                return 1;
-            }
+            picint(1 << 13);
+            return 1;
         }
     }
     CLOCK_CYCLES(4);
diff --git a/src/cpu/x87.c b/src/cpu/x87.c
index 390c06dc2..577fa1a40 100644
--- a/src/cpu/x87.c
+++ b/src/cpu/x87.c
@@ -355,7 +355,10 @@ FPU_exception(uint32_t fetchdat, uint16_t exceptions, int store)
                 nmi = 1;
             }
 #else
-            picint(1 << 13);
+           if (is486 && (cr0 & 0x20))
+               x86_int(16);
+            else
+                picint(1 << 13);
 #endif // FPU_8087
         }
         return unmasked;
diff --git a/src/cpu/x87.h b/src/cpu/x87.h
index 060f2fe27..2ad0c7b10 100644
--- a/src/cpu/x87.h
+++ b/src/cpu/x87.h
@@ -228,12 +228,10 @@ FPU_save_regi_tag(extFloat80_t reg, int tag, int stnr)
 #define FPU_check_pending_exceptions()        \
     do {                                      \
         if (fpu_state.swd & FPU_SW_Summary) { \
-            if (cr0 & 0x20) {                 \
+            if (is486 && (cr0 & 0x20))        \
                 x86_int(16);                  \
-                return 1;                     \
-            } else {                          \
+            else                              \
                 picint(1 << 13);              \
-                return 1;                     \
-            }                                 \
+            return 1;                         \
         }                                     \
     } while (0)
diff --git a/src/cpu/x87_ops.h b/src/cpu/x87_ops.h
index 6be9d7648..e1bc5858a 100644
--- a/src/cpu/x87_ops.h
+++ b/src/cpu/x87_ops.h
@@ -99,7 +99,10 @@ typedef union {
                     dst = src1 / (double) src2;         \
                 else {                                  \
                     fpu_log("FPU : divide by zero\n");  \
-                    picint(1 << 13);                    \
+                    if (is486 && (cr0 & 0x20))          \
+                        x86_int(16);                    \
+                    else                                \
+                        picint(1 << 13);                \
                     return 1;                           \
                 }                                       \
             } else                                      \