acknowledge requests after handling them

agb/interrupt_handler.s

@@ -4,16 +4,36 @@
     .section .iwram, "ax"
     .align
 InterruptHandler:
-    ldr r2, =0x04000200 @ interrupt enable register location
+    mov r2, #0x04000000 @ interrupt enable register location
+    add r2, #0x200
 
     mov r1, #0
     strh r1, [r2, #8]
 
-    push {r2}
-
     ldrh r1, [r2] @ load 16 bit interrupt enable to r1
     ldrh r3, [r2, #2] @ load 16 bit interrupt request to r3
     and r0, r1, r3 @ interrupts both enabled and requested
+
+    @ change to system mode
+    mrs r1, cpsr
+    orr r1, r1, #0xD
+    msr cpsr_c, r1
+
+    @ call the rust interrupt handler with r0 set to the triggered interrupts
+    ldr r1, =__RUST_INTERRUPT_HANDLER
+    push {lr, r2}
+    mov lr, pc
+    bx r1
+    pop {lr, r2}
+
+    @ change back to interrupt mode
+    mrs r1, cpsr
+    bic r1, r1, #0xD
+    msr cpsr_c, r1
+
+    mov r1, #1
+    strh r1, [r2, #8]
+
     strh r0, [r2, #2] @ store to interrupt request
 
     ldr r2, =0x03007FF8 @ load bios interrupt request location
@@ -21,27 +41,5 @@ InterruptHandler:
     orr r1, r1, r0 @ or with enabled and requested interrupts
     strh r1, [r2] @ acknowlege bios requests
 
-    @ change to system mode
-    mrs r2, cpsr
-    orr r2, r2, #0xD
-    msr cpsr_c, r2
-
-    @ call the rust interrupt handler with r0 set to the triggered interrupts
-    ldr r1, =__RUST_INTERRUPT_HANDLER
-    push {lr}
-    mov lr, pc
-    bx r1
-    pop {lr}
-
-    @ change back to interrupt mode
-    mrs r2, cpsr
-    bic r2, r2, #0xD
-    msr cpsr_c, r2
-
-    pop {r2}
-
-    mov r1, #1
-    strh r1, [r2, #8]
-
     bx lr @ return to bios
 .pool

agb/src/interrupt.rs

@@ -139,12 +139,14 @@ static mut INTERRUPT_TABLE: [InterruptRoot; 14] = [
 ];
 
 #[no_mangle]
-extern "C" fn __RUST_INTERRUPT_HANDLER(interrupt: u16) {
+extern "C" fn __RUST_INTERRUPT_HANDLER(interrupt: u16) -> u16 {
     for (i, root) in unsafe { INTERRUPT_TABLE.iter().enumerate() } {
         if (1 << i) & interrupt != 0 {
             root.trigger_interrupts();
         }
     }
+
+    interrupt
 }
 
 pub struct InterruptClosureBounded<'a> {