__fixtfsi: Set the "Invalid operation" exception for infinities, NaNs…

… and values outside of the valid range

include/gcc_vr4300/soft_float.h

@@ -0,0 +1,30 @@
+#ifndef GCC_VR4300_SOFT_FLOAT_H
+#define GCC_VR4300_SOFT_FLOAT_H
+
+#include "types.h"
+
+static inline bool Fpcsr_IsEnabled_InvalidOperation(void) {
+    uint32_t fpcsr;
+
+    __asm__("cfc1 %0, $31" : "=r"(fpcsr));
+
+    return (fpcsr & (1 << 11)) ? 1 : 0;
+}
+
+/**
+ * Set the "Invalid operation" exception.
+ *
+ * If the "Enable bit" for this exception is turned on then the hardware will
+ * trigger the exception by itself.
+ */
+static inline void Fpcsr_SetCause_InvalidOperation(void) {
+    uint32_t fpcsr;
+
+    __asm__("cfc1 %0, $31" : "=r"(fpcsr));
+
+    fpcsr |= (1 << 11);
+
+    __asm__("ctc1 %0, $31" : : "r"(fpcsr));
+}
+
+#endif

src/soft_float/int_from_float/__fixtfsi.c

@@ -3,6 +3,7 @@
 
 #include "gcc_vr4300/types.h"
 #include "gcc_vr4300/export.h"
+#include "gcc_vr4300/soft_float.h"
 
 #if ABI_N32 || ABI_N64
 EXPORT(__fixtfsi);
@@ -24,7 +25,6 @@ int32_t __fixtfsi(float128 a) {
     int32_t realExponent;
     bool mantissaIsZero;
     int32_t computedValue;
-
     uint32_t truncantedMantissa;
 
     flt.ld = a;
@@ -55,42 +55,26 @@ int32_t __fixtfsi(float128 a) {
         return 0;
     }
 
+    // If value if infinity, NaN or outside of `int32_t` range then trigger the "Invalid operation" exception
+    // If said exception is disabled then return `2^31 - 1`
+
     if (encodedExponent == 0x7FFF) {
         // Infinity and NaN
 
-        if (mantissaIsZero) {
-            // Infinity, return max int
-
-            // TODO: should this be handled in any other way?
-
-            if (sign) {
-                return INT32_MIN;
-            } else {
-                return INT32_MAX;
-            }
-        }
-
-        // NaN
-        return 0; // ?
+        Fpcsr_SetCause_InvalidOperation();
+        return 0xFFFFFFFF;
     }
 
-    // TODO: Figure out proper way to handle values outside of the int32_t range
-
     if (realExponent < 0) {
         // Value smaller than 1, truncate to zero (?)
         return 0;
     }
 
     if (realExponent > 31) {
-        // Value is larger than int32_t, return int max
-
-        // TODO: should this be handled in any other way?
+        // Value is larger than int32_t
 
-        if (sign) {
-            return INT32_MIN;
-        } else {
-            return INT32_MAX;
-        }
+        Fpcsr_SetCause_InvalidOperation();
+        return 0xFFFFFFFF;
     }
 
     if (mantissaIsZero) {