Move PIT config into rust

rust_experiments/src/lib.rs

@@ -38,6 +38,34 @@ pub extern fn rust_handle_timer() {
     timer_callback(gtc);
 }
 
+#[no_mangle]
+pub extern fn rust_setup_PIT() {
+    PIT::configure_PIT(PIT::MILLISECOND_CONSTANT);
+}
+
+mod PIT {
+    use x86_asm::{outb, inb, iowait};
+
+    const PIT_CH0: u16      = 0x40;
+    const PIT_MODE_CMD: u16 = 0x43;
+
+    //channel 0, low-byte/hi-byte, rate generator
+    const TIMER_CONFIG_SPECIFIER: u8 = 0b00_11_010_0;
+
+    //generate ticks at about 1000.15 Hz
+    pub const MILLISECOND_CONSTANT: u16 = 1193;
+
+    pub fn configure_PIT(timer_divider: u16) {
+        unsafe {
+            outb(PIT_MODE_CMD, TIMER_CONFIG_SPECIFIER);
+            let low_bits = (timer_divider & 0xff) as u8;
+            let high_bits = (timer_divider >> 8) as u8;
+            outb(PIT_CH0, low_bits);
+            outb(PIT_CH0, high_bits);
+        }
+    }
+}
+
 mod PIC {
     use x86_asm::{outb, inb, iowait};
 

rust_experiments/src/long_mode_init.asm

@@ -11,7 +11,9 @@ long_mode_start:
     ; print "OKAY"
     call setup_SSE
     call setup_IDT
-    call setup_PIT
+    extern rust_setup_PIT
+    call rust_setup_PIT
+    ;call setup_PIT
     extern rust_setup_PIC
     call rust_setup_PIC
     extern rust_main
@@ -159,19 +161,3 @@ idt64:
     dq idt64
 
 ; --------- end of IDT section --------
-
-setup_PIT:
-%define PIT_CH0 0x40
-%define PIT_MODE_CMD 0x43
-%define TIMER_CONSTANT 1193 ;generates ticks at 1000.15 Hz
-
-    mov al, 0b00_11_010_0 ; channel 0, low-byte/hi-byte, rate generator
-    out PIT_MODE_CMD, al
-
-    mov ax, TIMER_CONSTANT
-    out PIT_CH0, al
-    mov al, ah
-    out PIT_CH0, al
-
-    ret
-