initial razzle

kernel/syscall.c

@@ -0,0 +1,64 @@
+#pragma once
+
+#include "scheduler.c"
+#include "ps2.c"
+
+#ifdef ARCH_I386
+#include "../arch/i386/syscall.c"
+#endif
+
+enum syscall_type_d { SYSCALL_yield, SYSCALL_getc, SYSCALL_exit };
+
+void yield() { INVOKE_SYSCALL(SYSCALL_yield); }
+char getc() { 
+    INVOKE_SYSCALL(SYSCALL_getc); 
+
+    char result;
+    __asm__ volatile (
+        "movb %%al, %0"  
+        : "=r"(result)  
+    );
+
+    return result;
+}
+
+void __syscall_yield(struct regs *r) {
+  // for now, just reschedule
+  // TODO: reset PIT timer so
+  // next process doesn't get an
+  // unreasonably small quantum
+
+  schedule(r);
+}
+
+void syscall(struct regs *r) {
+  int syscall_no = r->eax;
+
+  switch (syscall_no) {
+  case SYSCALL_yield: {
+    __syscall_yield(r);
+    break;
+  };
+
+  case SYSCALL_getc: {
+    process_table[current_pid].state = TASKSTATE_blocked;
+
+    for(uint32_t i = 0; i < MAX_PROCESSES; i++) {
+        if(!ps2_waiters[i].alloc) {
+            ps2_waiters[i].alloc = 1;
+            ps2_waiters[i].pid = current_pid;
+            break;
+        }
+    }
+
+    __syscall_yield(r);
+    break;
+  };
+
+  case SYSCALL_exit: {
+    process_table[current_pid].state = TASKSTATE_unused;
+    __syscall_yield(r);
+    break;
+  };
+  }
+}