Altera DE1-SoC - Page 28

DE1-SOC COMPUTER SYSTEM WITH NIOS II For Quartus II 15.0
asm ( "ldw r8, 32(sp)" );
asm ( "ldw r9, 36(sp)" );
asm ( "ldw r10, 40(sp)" );
asm ( "ldw r11, 44(sp)" );
asm ( "ldw r12, 48(sp)" );
asm ( "ldw r13, 52(sp)" );
asm ( "ldw r14, 56(sp)" );
asm ( "ldw r15, 60(sp)" );
asm ( "ldw r16, 64(sp)" );
asm ( "ldw r17, 68(sp)" );
asm ( "ldw r18, 72(sp)" );
asm ( "ldw r19, 76(sp)" );
asm ( "ldw r20, 80(sp)" );
asm ( "ldw r21, 84(sp)" );
asm ( "ldw r22, 88(sp)" );
asm ( "ldw r23, 92(sp)" );
asm ( "ldw r24, 96(sp)" );
asm ( "ldw r25, 100(sp)" ); // r25 = bt
asm ( "ldw r26, 104(sp)" ); // r26 = gp
// skip r27 because it is sp, and we did not save this on the stack
asm ( "ldw r28, 112(sp)" ); // r28 = fp
asm ( "ldw r29, 116(sp)" ); // r29 = ea
asm ( "ldw r30, 120(sp)" ); // r30 = ba
asm ( "ldw r31, 124(sp)" ); // r31 = ra
asm ( "addi sp, sp, 128" );
asm ( "eret" );
}
/********************************************************************************
* Interrupt Service Routine: Determines the interrupt source and calls the appropriate subroutine
*******************************************************************************/
void interrupt_handler(void)
{
int ipending;
NIOS2_READ_IPENDING(ipending);
if ( ipending & 0x1 ) // interval timer is interrupt level 0
interval_timer_isr( );
if ( ipending & 0x2 ) // pushbuttons are interrupt level 1
pushbutton_ISR( );
// else, ignore the interrupt
return;
}
Figure 22. Reset and exception handler C code (Part c).
28 Altera Corporation - University Program
2015