Seamless task switching

kernel/elf.c

@@ -25,7 +25,7 @@ void run_program(uint8_t* code, size_t code_length, uint8_t* data, size_t data_l
     struct CPUState target = {
         .eip = (size_t) userland_code,
         .esp = 0x00400800,
-        .eax = 0x00400800,
+        .eax = 0x00400000,
         .ebx = 0,
         .ecx = 0,
         .edx = 0,

kernel/kernel.c

@@ -15,12 +15,13 @@
 
 uint8_t program[] = {
     0xcd, 0x80, // int $0x80
-    0xb9, 0x02, 0x00, 0x00, 0x00, // mov $0, %ecx
     0xff, 0xe1, // jmp *%ecx
 };
 
-// uint8_t data[] = "Hello From Userspace\n";
-uint8_t data[] = {};
+uint8_t data[] = "Hello From Userspace\n";
+
+uint8_t kernel_data[] = "Hello From Kernelspace\n";
+// uint8_t data[] = {};
 
 void irq0();
 
@@ -50,6 +51,8 @@ void kernel_main(void)
     while (true) {
         i += 1;
         if (i == 1 << 16) {
+            asm("mov %0, %%eax" :: "r" (kernel_data) );
+            asm("mov $0, %ecx");
             asm("int $0x80");
             i = 0;
         }

kernel/syscall.c

@@ -25,7 +25,6 @@ static void input(char* buffer)
 
 void _syscall(uint32_t a, uint32_t b, uint32_t c)
 {
-    /*
     switch (c) {
         case 0x00:
             print((char*) a);
@@ -34,6 +33,4 @@ void _syscall(uint32_t a, uint32_t b, uint32_t c)
             input((char*) a);
             break;
     }
-    */
-    terminal_writestring("waow :3\n");
 }