feat: TrueType (TTF) font rendering, many new desktop applications and DOOM support, among other improvements

kernel/src/Sched/Context.asm

@@ -1,18 +1,30 @@
 ;
 ;   Context.asm
-;   Context switch: save/restore callee-saved registers, stack pointer, and CR3
+;   Context switch: save/restore callee-saved registers, stack pointer, CR3, and FPU state
 ;   Copyright (c) 2025 Daniel Hammer
 ;
 
 [bits 64]
 section .text
 
-; void SchedContextSwitch(uint64_t* oldRsp, uint64_t newRsp, uint64_t newCR3)
+; void SchedContextSwitch(uint64_t* oldRsp, uint64_t newRsp, uint64_t newCR3,
+;                         uint8_t* oldFpuArea, uint8_t* newFpuArea)
 ;   rdi = pointer to save old RSP
 ;   rsi = new RSP to restore
 ;   rdx = new PML4 physical address (for CR3)
+;   rcx = old FPU state area (may be null)
+;   r8  = new FPU state area (may be null)
 global SchedContextSwitch
 SchedContextSwitch:
+    ; Save FPU state before pushing registers (rcx/r8 are caller-saved)
+    test rcx, rcx
+    jz .skip_fxsave
+    fxsave [rcx]
+.skip_fxsave:
+
+    ; Stash r8 in r9 (callee-saved registers will clobber r8 slot on stack)
+    mov r9, r8
+
     ; Save callee-saved registers on the current stack
     push rbp
     push rbx
@@ -42,4 +54,10 @@ SchedContextSwitch:
     pop rbx
     pop rbp
 
+    ; Restore FPU state
+    test r9, r9
+    jz .skip_fxrstor
+    fxrstor [r9]
+.skip_fxrstor:
+
     ret

kernel/src/Sched/Scheduler.cpp

@@ -14,9 +14,11 @@
 #include <CppLib/Stream.hpp>
 #include <Hal/Apic/Apic.hpp>
 #include <Hal/GDT.hpp>
+#include <Api/WinServer.hpp>
 
-// Assembly: context switch with CR3 parameter
-extern "C" void SchedContextSwitch(uint64_t* oldRsp, uint64_t newRsp, uint64_t newCR3);
+// Assembly: context switch with CR3 and FPU state parameters
+extern "C" void SchedContextSwitch(uint64_t* oldRsp, uint64_t newRsp, uint64_t newCR3,
+                                   uint8_t* oldFpuArea, uint8_t* newFpuArea);
 
 // Assembly: jump to user mode via IRETQ
 extern "C" void JumpToUserMode(uint64_t rip, uint64_t rsp);
@@ -66,7 +68,7 @@ namespace Sched {
         for (int i = 0; i < MaxProcesses; i++) {
             processTable[i].pid = i;
             processTable[i].state = ProcessState::Free;
-            processTable[i].name = nullptr;
+            processTable[i].name[0] = '\0';
             processTable[i].savedRsp = 0;
             processTable[i].stackBase = 0;
             processTable[i].entryPoint = 0;
@@ -191,7 +193,11 @@ namespace Sched {
         Process& proc = processTable[slot];
         proc.pid = nextPid++;
         proc.state = ProcessState::Ready;
-        proc.name = vfsPath;
+        {
+            int i = 0;
+            for (; i < 63 && vfsPath[i]; i++) proc.name[i] = vfsPath[i];
+            proc.name[i] = '\0';
+        }
         proc.savedRsp = (uint64_t)sp;
         proc.stackBase = (uint64_t)kernelStackBase;
         proc.entryPoint = entry;
@@ -224,6 +230,11 @@ namespace Sched {
         proc.termCols = 0;
         proc.termRows = 0;
 
+        // Initialize FPU state: zero out, then set default FCW and MXCSR
+        memset(proc.fpuState, 0, 512);
+        *(uint16_t*)&proc.fpuState[0] = 0x037F;   // FCW: default x87 control word
+        *(uint32_t*)&proc.fpuState[24] = 0x1F80;   // MXCSR: default SSE control/status
+
         return proc.pid;
     }
 
@@ -276,7 +287,9 @@ namespace Sched {
         // Update TSS RSP0 for hardware interrupts from ring 3
         Hal::g_tss.rsp0 = processTable[next].kernelStackTop;
 
-        SchedContextSwitch(oldRspPtr, processTable[next].savedRsp, newCR3);
+        uint8_t* oldFpu = (currentPid >= 0) ? processTable[currentPid].fpuState : nullptr;
+        uint8_t* newFpu = processTable[next].fpuState;
+        SchedContextSwitch(oldRspPtr, processTable[next].savedRsp, newCR3, oldFpu, newFpu);
     }
 
     void Tick() {
@@ -309,6 +322,9 @@ namespace Sched {
             return;
         }
 
+        // Clean up any windows owned by this process
+        WinServer::CleanupProcess(processTable[currentPid].pid);
+
         processTable[currentPid].state = ProcessState::Terminated;
 
         int next = -1;
@@ -329,11 +345,13 @@ namespace Sched {
             g_kernelRsp = processTable[next].kernelStackTop;
             Hal::g_tss.rsp0 = processTable[next].kernelStackTop;
 
-            SchedContextSwitch(&processTable[old].savedRsp, processTable[next].savedRsp, newCR3);
+            SchedContextSwitch(&processTable[old].savedRsp, processTable[next].savedRsp, newCR3,
+                              processTable[old].fpuState, processTable[next].fpuState);
         } else {
             int old = currentPid;
             currentPid = -1;
-            SchedContextSwitch(&processTable[old].savedRsp, idleSavedRsp, GetKernelCR3());
+            SchedContextSwitch(&processTable[old].savedRsp, idleSavedRsp, GetKernelCR3(),
+                              processTable[old].fpuState, nullptr);
         }
 
         for (;;) {
@@ -362,4 +380,9 @@ namespace Sched {
         return nullptr;
     }
 
+    Process* GetProcessSlot(int slot) {
+        if (slot < 0 || slot >= MaxProcesses) return nullptr;
+        return &processTable[slot];
+    }
+
 }

kernel/src/Sched/Scheduler.hpp

@@ -30,7 +30,7 @@ namespace Sched {
     struct Process {
         int pid;
         ProcessState state;
-        const char* name;
+        char name[64];
         uint64_t savedRsp;
         uint64_t stackBase;       // Bottom of allocated kernel stack (lowest address)
         uint64_t entryPoint;
@@ -58,6 +58,9 @@ namespace Sched {
         // GUI terminal dimensions (set by desktop, read by SYS_TERMSIZE)
         int termCols = 0;
         int termRows = 0;
+
+        // FPU/SSE state (FXSAVE format, must be 16-byte aligned)
+        uint8_t fpuState[512] __attribute__((aligned(16)));
     };
 
     void Initialize();
@@ -82,4 +85,7 @@ namespace Sched {
     // Find a process by PID (returns nullptr if not found or not alive)
     Process* GetProcessByPid(int pid);
 
+    // Get a pointer to slot i in the process table (for enumeration)
+    Process* GetProcessSlot(int slot);
+
 }