From e7c20b30331e2c5be96c34586849b8b4e4bfc640 Mon Sep 17 00:00:00 2001
From: MarcZX100 <marczxrr@gmail.com>
Date: Sun, 11 Oct 2026 14:35:01 +0000
Subject: [PATCH] feat(libc): export isnanf and __signbitl

---
 core/libs/prx/libc/src/Math.cpp |  5 +++++
 core/libs/tests/GuestMath.cpp   | 18 ++++++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/core/libs/prx/libc/src/Math.cpp b/core/libs/prx/libc/src/Math.cpp
index 9d6a8aebd..ba60360b1 100644
--- a/core/libs/prx/libc/src/Math.cpp
+++ b/core/libs/prx/libc/src/Math.cpp
@@ -169,6 +169,7 @@ short APS5_VABI _FDtest_nid_postfix(const float* value) {
     return Finite;
 }
 int APS5_VABI __isnanf_nid_postfix(float x) { return std::isnan(x) ? 1 : 0; }
+int APS5_VABI isnanf_nid_postfix(float x) { return __isnanf_nid_postfix(x); }
 int APS5_VABI __fpclassifyf_nid_postfix(float x) {
     constexpr int Infinite = 0x01, NotANumber = 0x02, Normal = 0x04, Subnormal = 0x08, Zero = 0x10;
     std::uint32_t bits;
@@ -180,6 +181,10 @@ int APS5_VABI __fpclassifyf_nid_postfix(float x) {
     return Normal;
 }
 int APS5_VABI __signbitf_nid_postfix(float x) { return std::signbit(x) ? 1 : 0; }
+int APS5_VABI __signbitl_nid_postfix(long double x) {
+    static_assert(sizeof(long double) == 16, "guest long double requires x87 extended precision storage");
+    return std::signbit(x) ? 1 : 0;
+}
 
 static std::mutex g_randLock;
 static std::uint32_t g_randState = 1;
diff --git a/core/libs/tests/GuestMath.cpp b/core/libs/tests/GuestMath.cpp
index 6d56671b5..01fdbd1f8 100644
--- a/core/libs/tests/GuestMath.cpp
+++ b/core/libs/tests/GuestMath.cpp
@@ -37,6 +37,8 @@ extern LibcFloatConstant _FInf_nid_postfix;
 extern LibcFloatConstant _FNan_nid_postfix;
 short APS5_VABI _FDtest_nid_postfix(const float*);
 int APS5_VABI __fpclassifyf_nid_postfix(float);
+int APS5_VABI isnanf_nid_postfix(float);
+int APS5_VABI __signbitl_nid_postfix(long double);
 float APS5_VABI fmodf_nid_postfix(float, float);
 float APS5_VABI asinf_nid_postfix(float);
 float APS5_VABI acosf_nid_postfix(float);
@@ -328,6 +330,21 @@ static void CheckFloatClassification() {
     Require(_FDtest_nid_postfix(reinterpret_cast<const float*>(&_FNan_nid_postfix)) == 2);
 }
 
+static void CheckMissingClassificationExports() {
+    const float infinity = std::numeric_limits<float>::infinity();
+    const float nan = std::numeric_limits<float>::quiet_NaN();
+    Require(isnanf_nid_postfix(nan) == 1);
+    Require(isnanf_nid_postfix(infinity) == 0 && isnanf_nid_postfix(-infinity) == 0);
+    Require(isnanf_nid_postfix(0.f) == 0 && isnanf_nid_postfix(-1.f) == 0);
+
+    const long double negativeNan = std::copysign(std::numeric_limits<long double>::quiet_NaN(), -1.L);
+    Require(__signbitl_nid_postfix(0.L) == 0 && __signbitl_nid_postfix(-0.L) == 1);
+    Require(__signbitl_nid_postfix(1.L) == 0 && __signbitl_nid_postfix(-1.L) == 1);
+    Require(__signbitl_nid_postfix(std::numeric_limits<long double>::infinity()) == 0);
+    Require(__signbitl_nid_postfix(-std::numeric_limits<long double>::infinity()) == 1);
+    Require(__signbitl_nid_postfix(negativeNan) == 1);
+}
+
 static void CheckDoubleRounding(double value, std::int64_t expected, bool invalid) {
     for (const bool useLlround : {false, true}) {
         std::feclearexcept(FE_ALL_EXCEPT);
@@ -352,6 +369,7 @@ static void CheckFloatRounding(float value, std::int64_t expected, bool invalid)
 
 int main() {
     CheckFloatClassification();
+    CheckMissingClassificationExports();
     CheckIntegerConversions();
     Require(atof_nid_postfix(" -12.5tail") == -12.5);
     char* end = nullptr;