move keyboard and mouse out of HAL into a standalone ps2.sys driver, implement usb stack with xhci controller discovery, hid keyboard/mouse, and bulk-only mass storage, add pci msi support with capability chain walking and software irq vector allocation (slots 16-23), rewrite user virtual memory as a USER_VA_REGION descriptor arena with per-process ownership tracking and guard page support, replacing the old bump allocator and top-down image region, add MmCreateUserRegion/MmDestroyAllUserRegions so process teardown reclaims all user va in one pass, allocate a pool-backed shadow framebuffer in hal_screen to fix cursor tearing and scroll corruption, reserve ap trampoline page below 1mb in uefi bootloader before boot services exit, rewrite memset/memcpy/memmove/memcmp with __stosq/__movsq intrinsics, promote driver flag literals to macros and add multi-tu STANDALONE_DRIVERS table to build.c, split rtl8139/rtl816x into header+source, rename KbReadScancode to KbReadKey, improve page fault output with MmDebugDescribeAddress and user region dump, fix %p to %016llX throughout.

code/drivers/input/ps2/ps2_i8042.c

@@ -0,0 +1,64 @@
+// ps2_i8042.c - 8042 controller and device command helpers.
+#include "ps2.h"
+
+void Ps2Pause(void) {
+    _mm_pause();
+}
+
+void Ps2WaitInput(void) {
+    int timeout = 100000;
+    while ((__inbyte(PS2_STAT) & PS2_STAT_IN_FULL) && --timeout) {
+        Ps2Pause();
+    }
+}
+
+bool Ps2WaitOutput(void) {
+    int timeout = 5000000;
+    while (!(__inbyte(PS2_STAT) & PS2_STAT_OUT_FULL) && --timeout) {
+        Ps2Pause();
+    }
+    return timeout != 0;
+}
+
+void Ps2FlushOutput(void) {
+    int timeout = 100000;
+    while ((__inbyte(PS2_STAT) & PS2_STAT_OUT_FULL) && --timeout) {
+        (void)__inbyte(PS2_DATA);
+    }
+}
+
+uint8_t Ps2ReadData(void) {
+    if (!Ps2WaitOutput()) return 0xFFu;
+    return __inbyte(PS2_DATA);
+}
+
+void Ps2WriteCommand(uint8_t command) {
+    Ps2WaitInput();
+    __outbyte(PS2_CMD, command);
+}
+
+void Ps2WriteData(uint8_t data) {
+    Ps2WaitInput();
+    __outbyte(PS2_DATA, data);
+}
+
+uint8_t Ps2ReadCommandByte(void) {
+    Ps2WriteCommand(0x20u);
+    return Ps2ReadData();
+}
+
+void Ps2WriteCommandByte(uint8_t commandByte) {
+    Ps2WriteCommand(0x60u);
+    Ps2WriteData(commandByte);
+}
+
+bool Ps2SendKeyboard(uint8_t byte) {
+    Ps2WriteData(byte);
+    return Ps2ReadData() == 0xFAu;
+}
+
+bool Ps2SendMouse(uint8_t byte) {
+    Ps2WriteCommand(0xD4u);
+    Ps2WriteData(byte);
+    return Ps2ReadData() == 0xFAu;
+}