From 6a983fe33c9e9e0b841cde6e919792fd0e372a65 Mon Sep 17 00:00:00 2001
From: Aiken Harris <harraiken91@gmail.com>
Date: Mon, 27 Apr 2026 20:17:57 +0200
Subject: [PATCH] Add helper to translate run level to software interrupt
 vector

---
 xtoskrnl/hl/amd64/runlevel.cc    | 23 +++++++++++++++++++++++
 xtoskrnl/hl/i686/runlevel.cc     | 22 ++++++++++++++++++++++
 xtoskrnl/includes/hl/runlevel.hh |  1 +
 3 files changed, 46 insertions(+)

diff --git a/xtoskrnl/hl/amd64/runlevel.cc b/xtoskrnl/hl/amd64/runlevel.cc
index 8408c39..89eb510 100644
--- a/xtoskrnl/hl/amd64/runlevel.cc
+++ b/xtoskrnl/hl/amd64/runlevel.cc
@@ -20,6 +20,7 @@ XTFASTCALL
 KRUNLEVEL
 HL::RunLevel::GetRunLevel(VOID)
 {
+    /* Read current run level */
     return (KRUNLEVEL)AR::CpuFunc::ReadControlRegister(8);
 }
 
@@ -37,6 +38,7 @@ XTFASTCALL
 VOID
 HL::RunLevel::SetRunLevel(IN KRUNLEVEL RunLevel)
 {
+    /* Set new run level */
     AR::CpuFunc::WriteControlRegister(8, RunLevel);
 }
 
@@ -54,6 +56,7 @@ XTFASTCALL
 KRUNLEVEL
 HL::RunLevel::TransformApicTprToRunLevel(IN UCHAR Tpr)
 {
+    /* Transform APIC TPR to run level */
     return (KRUNLEVEL)(Tpr >> 4);
 }
 
@@ -71,5 +74,25 @@ XTFASTCALL
 UCHAR
 HL::RunLevel::TransformRunLevelToApicTpr(IN KRUNLEVEL RunLevel)
 {
+    /* Transform run level to APIC TPR */
     return (RunLevel << 4);
 }
+
+/**
+ * Transforms a given execution run level into a corresponding hardware interrupt vector
+ * suitable for software interrupts.
+ *
+ * @param RunLevel
+ *        Supplies the run level to be translated into a software interrupt vector.
+ *
+ * @return This routine returns the 8-bit APIC vector corresponding to the requested software interrupt level.
+ *
+ * @since XT 1.0
+ */
+XTFASTCALL
+UCHAR
+HL::RunLevel::TransformRunLevelToSoftwareVector(IN KRUNLEVEL RunLevel)
+{
+    /* Transform run level to APIC interrupt vector */
+    return TransformRunLevelToApicTpr(RunLevel) | 0xF;
+}
diff --git a/xtoskrnl/hl/i686/runlevel.cc b/xtoskrnl/hl/i686/runlevel.cc
index da2f75e..6cdf6e4 100644
--- a/xtoskrnl/hl/i686/runlevel.cc
+++ b/xtoskrnl/hl/i686/runlevel.cc
@@ -20,6 +20,7 @@ XTFASTCALL
 KRUNLEVEL
 HL::RunLevel::GetRunLevel(VOID)
 {
+    /* Read current run level */
     return TransformApicTprToRunLevel(HL::Pic::ReadApicRegister(APIC_TPR));
 }
 
@@ -37,6 +38,7 @@ XTFASTCALL
 VOID
 HL::RunLevel::SetRunLevel(IN KRUNLEVEL RunLevel)
 {
+    /* Set new run level */
     HL::Pic::WriteApicRegister(APIC_TPR, TransformRunLevelToApicTpr(RunLevel));
 }
 
@@ -131,3 +133,23 @@ HL::RunLevel::TransformRunLevelToApicTpr(IN KRUNLEVEL RunLevel)
     /* Return the TPR corresponding to the run level from the transformation table. */
     return TransformationTable[RunLevel];
 }
+
+/**
+ * Transforms a given execution run level into a corresponding hardware interrupt vector
+ * suitable for software interrupts.
+ *
+ * @param RunLevel
+ *        Supplies the run level to be translated into a software interrupt vector.
+ *
+ * @return This routine returns the 8-bit APIC vector corresponding to the requested software interrupt level.
+ *
+ * @since XT 1.0
+ */
+
+XTFASTCALL
+UCHAR
+HL::RunLevel::TransformRunLevelToSoftwareVector(IN KRUNLEVEL RunLevel)
+{
+    /* Transform run level to APIC interrupt vector */
+    return TransformRunLevelToApicTpr(RunLevel);
+}
diff --git a/xtoskrnl/includes/hl/runlevel.hh b/xtoskrnl/includes/hl/runlevel.hh
index 5283378..e17fb54 100644
--- a/xtoskrnl/includes/hl/runlevel.hh
+++ b/xtoskrnl/includes/hl/runlevel.hh
@@ -20,6 +20,7 @@ namespace HL
         public:
             STATIC XTFASTCALL KRUNLEVEL GetRunLevel(VOID);
             STATIC XTFASTCALL VOID SetRunLevel(IN KRUNLEVEL RunLevel);
+            STATIC XTFASTCALL UCHAR TransformRunLevelToSoftwareVector(IN KRUNLEVEL RunLevel);
 
         private:
             STATIC XTFASTCALL KRUNLEVEL TransformApicTprToRunLevel(IN UCHAR Tpr);