Added multitasking support for two tasks ;)

1 files changed, 37 insertions, 0 deletions

diff --git a/asm/int_clock_handler.asm b/asm/int_clock_handler.asm
new file mode 100644
index 0000000..dd0de96
--- /dev/null
+++ b/asm/int_clock_handler.asm
@@ -0,0 +1,37 @@
+global int_clock_handler
+[extern task_switch_next]
+
+CLOCK_COUNTER:
+    db 0x00
+
+[bits 32]
+int_clock_handler:
+ 
+ ;Notice there is no IRQ number or error code - we don't need them
+
+ inc byte [CLOCK_COUNTER]
+ 
+ cmp byte  [CLOCK_COUNTER], 0x10
+
+ jne skip_clock
+
+ mov byte [CLOCK_COUNTER], 0x00
+
+ pusha          ;Push all standard registers
+
+ push esp       ;Push pointer to all the stuff we just pushed
+
+ call task_switch_next ;Call C code
+ 
+ mov esp, eax   ;Replace the stack with what the C code gave us
+
+ popa           ;Put the standard registers back
+ 
+ skip_clock:
+
+ mov al, 0x20   ;Port number AND command number to Acknowledge IRQ
+ out 0x20, al     ;Acknowledge IRQ, so we keep getting interrupts
+
+ ;We didn't push an error code or IRQ number, so we don't have to edit esp now
+ 
+ iret           ;Interrupt-Return