feat: e100e Ethernet driver, ramdisk reorganization, shell rewrite, web server/client, and more

kernel/src/Pci/Pci.cpp

@@ -223,6 +223,32 @@ namespace Pci {
         return LegacyRead8(bus, device, function, (uint8_t)offset);
     }
 
+    // -------------------------------------------------------------------------
+    // PCI capability list traversal
+    // -------------------------------------------------------------------------
+
+    uint8_t FindCapability(uint8_t bus, uint8_t device, uint8_t function, uint8_t capId) {
+        // Check Status register bit 4 (Capabilities List present)
+        uint16_t status = ReadConfig16(bus, device, function, RegStatus);
+        if (!(status & (1 << 4))) {
+            return 0;
+        }
+
+        // Read Capabilities Pointer (offset 0x34), mask to dword-aligned
+        uint8_t offset = ReadConfig8(bus, device, function, 0x34) & 0xFC;
+
+        // Walk the linked list (cap_id @ +0, next_ptr @ +1)
+        while (offset != 0) {
+            uint8_t id = ReadConfig8(bus, device, function, offset);
+            if (id == capId) {
+                return offset;
+            }
+            offset = ReadConfig8(bus, device, function, offset + 1) & 0xFC;
+        }
+
+        return 0;
+    }
+
     // -------------------------------------------------------------------------
     // PCI class code names
     // -------------------------------------------------------------------------

kernel/src/Pci/Pci.hpp

@@ -60,6 +60,13 @@ namespace Pci {
     void LegacyWrite16(uint8_t bus, uint8_t device, uint8_t function, uint8_t offset, uint16_t value);
     void LegacyWrite32(uint8_t bus, uint8_t device, uint8_t function, uint8_t offset, uint32_t value);
 
+    // PCI capability IDs
+    constexpr uint8_t PCI_CAP_MSI = 0x05;
+
+    // Walk the PCI capability linked list for a given device.
+    // Returns the config-space offset of the capability, or 0 if not found.
+    uint8_t FindCapability(uint8_t bus, uint8_t device, uint8_t function, uint8_t capId);
+
     // Class code name lookup
     const char* GetClassName(uint8_t classCode, uint8_t subClass);