Vga graphics (#14)

* green screen

* somewhat working

* back to text

* cleanup

* small syscall to draw pixels from userspace

kernel/src/interrupt.rs

@@ -6,6 +6,7 @@ use crate::kprint;
 use crate::kprintln;
 use crate::time;
 use crate::userland;
+use crate::util::out_port_b;
 use crate::USERLAND;
 use core::arch::asm;
 use core::arch::global_asm;
@@ -138,17 +139,6 @@ pub extern "C" fn irq_handler(int_no: u64) {
     out_port_b(0x20, 0x20);
 }
 
-fn out_port_b(port: u16, value: u8) {
-    unsafe {
-        asm!(
-            r#"out %al, %dx"#,
-            in("dx") port,
-            in("al") value,
-            options(att_syntax)
-        );
-    }
-}
-
 fn set_idt_gate(num: usize, base: u64, sel: u16, flags: u8) {
     unsafe {
         IDT_ENTRIES[num].base_low = (base & 0xFFFF) as u16;

kernel/src/kernel.rs

@@ -14,6 +14,8 @@ mod process;
 mod syscall;
 mod time;
 mod userland;
+mod util;
+mod vga;
 
 /// This function is called on panic.
 #[panic_handler]
@@ -38,6 +40,12 @@ pub extern "C" fn kernel_main() -> ! {
     kprintln!("successfull boot!");
     kprintln!("Hellö Wörld!");
 
+    vga::vga_enter();
+    vga::vga_clear_screen();
+
+    //vga::vga_exit();
+    //kprintln!("Back in text mode");
+
     // Trigger test exception
     //unsafe {
     //    asm!("int3", options(nomem, nostack));

kernel/src/syscall.rs

@@ -1,3 +1,4 @@
+use crate::vga::{vga_flip, vga_plot_pixel};
 use crate::USERLAND;
 use crate::{kprintln, logging::log};
 use core::arch::asm;
@@ -16,13 +17,34 @@ pub extern "C" fn system_call() -> u64 {
     match syscall_nr {
         1 => return syscall_write(),
         2 => return syscall_getpid(),
+        3 => return syscall_plot_pixel(),
         _ => {
             kprintln!("Undefined system call triggered");
             return 0xdeadbeef;
         }
     }
 }
 
+fn syscall_plot_pixel() -> u64 {
+    let mut x: u32;
+    let mut y: u32;
+    let mut color: u32;
+
+    unsafe {
+        // TODO this must be possible more elegantly
+        asm!("",
+            out("r8") x,
+            out("r9") y,
+            out("r10") color
+        );
+    }
+
+    vga_plot_pixel(x, y, color as u8);
+    vga_flip();
+
+    return 0;
+}
+
 fn syscall_getpid() -> u64 {
     USERLAND.lock().get_current_process_id() as u64
 }

kernel/src/util.rs

@@ -0,0 +1,20 @@
+use core::arch::asm;
+
+pub fn out_port_b(port: u32, value: u8) {
+    unsafe {
+        asm!(
+            r#"out %al, %dx"#,
+            in("edx") port,
+            in("al") value,
+            options(att_syntax)
+        );
+    }
+}
+
+pub fn in_port_b(port: u32) -> u8 {
+    let mut key;
+    unsafe {
+        asm!("in al, dx", out("al") key, in("rdx") port);
+    }
+    return key;
+}