ptos/amd64: cpu: Add high-level interrupt registration

Signed-off-by: Chloe M <chloe@mensia.org>

service/ptos/arch/amd64/cpu/intr.c

@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause.
+ *
+ * Description: High-level interrupt management
+ * Author:      Chloe M.
+ */
+
+#include <hal/intr.h>
+#include <machine/intr.h>
+#include <machine/idt.h>
+#include <ptdef.h>
+
+/* Globals */
+static INTR_HANDLER HandlerTable[256];
+
+UCHAR
+HalIntrRegister(INTR_HANDLER *Handler, BOOLEAN IsUser)
+{
+    UCHAR VectorBase, Vector;
+    INTR_HANDLER *HandlerSlot;
+
+    /*
+     * We have 16 priorities at every band as 4-bits makes up
+     * the interrupt priority level. Our job is to find a slot
+     * that is free for our interrupt handler at its given IRQL.
+     */
+    VectorBase = MAX(Handler->Irql << IPRI_CLASS_SHIFT, 0x20);
+    for (Vector = VectorBase; Vector < Vector + 16; ++Vector) {
+        /* Skip system reserved vectors */
+        switch (Vector) {
+        /* Timer vector */
+        case 0x81: continue;
+        /* System call vector */
+        case 0x2E: continue;
+        }
+
+        /* Don't overwrite present entries */
+        HandlerSlot = &HandlerTable[Vector];
+        if (Handler->Present) {
+            continue;
+        }
+
+        *HandlerSlot = *Handler;
+        HandlerSlot->Present = 1;
+        MdIdtSetGate(
+            Vector,
+            (UPTR)Handler->Handler,
+            (IsUser) ? IDT_USER_GATE : IDT_INT_GATE,
+            0
+        );
+
+        return Vector;
+    }
+
+    /* No more vectors */
+    return 0;
+}

service/ptos/head/arch/amd64/intr.h

@@ -0,0 +1,15 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause.
+ *
+ * Description: High-level interrupt management
+ * Author:      Chloe M.
+ */
+
+#ifndef _MACHINE_INTR_H_
+#define _MACHINE_INTR_H_ 1
+
+/* Interrupt priority class shift operand */
+#define IPRI_CLASS_SHIFT 4
+
+#endif  /* !_MACHINE_INTR_H_ */

service/ptos/head/hal/intr.h

@@ -10,6 +10,7 @@
 #define _HAL_INTR_H_ 1
 
 #include <ptdef.h>
+#include <ptapi/status.h>
 
 /*
  * Represents value interrupt request levels that can be set within
@@ -40,4 +41,15 @@ typedef struct _INTR_HANDLER {
     BOOLEAN Present;
 } INTR_HANDLER;
 
+/*
+ * Register an interrupt handler and obtain the interrupt
+ * vector.
+ *
+ * @Handler:  Handler to register
+ * @IsUser:   If set, is user-level interrupt
+ *
+ * Returned values of zero are invalid
+ */
+UCHAR HalIntrRegister(INTR_HANDLER *Handler, BOOLEAN IsUser);
+
 #endif  /* !_HAL_INTR_H_ */