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Boise State University
Department of Electrical and Computer Engineering
ECE 332 Microprocessors, Quiz 5 โ October 3, 2007 ( this is a 30 points quiz )
Name: ______________________________
1. Show the outputs generated by this program.
#include <stdio.h>
#define COUNT 2 unsigned int i=0;
void f2() { i++; }
unsigned int f1(unsigned int x, unsigned int y) { static count = 0;
count++; f2(); printf("count = %d\n", count); return (x+y); }
int main(void) { unsigned int i=1; i++; { unsigned int i, sum=0; for (i=0;i<COUNT;i++) { sum = f1(i,i+1); printf(" i = %d\n", i); } printf(" i = %d\n", i);
} printf(" i = %d\n", i); }
Output:
count = 1
i = 0
count = 2
i = 1
i = 2
i = 2
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2. Explain the role of registers ctl0, ctl1, ctl3, and ctl4.
ctl0 โ only one-bit is used, the PIE bit determine whether the processor will accept interrupt.
ctl1 โ a copy of ctl0 is saved to ctl1 when an exception occurred.
ctl3 โ show which hardware irq has been enable
ctl4 โ show what irq is outstanding
3. What is the purpose of ISR?
ISR โ interrupt service routine. The objective of ISR is to service interrupt.
4. Write an assembly program to sum the following numbers.
VCOUNT: .word 8 VALUES: .word 2,3,5,7,11,13,17,
movia r5,VCOUNT # address of value count
ldw r3,0(r5) # value count
movia r7,VALUES # address of values
movi r2,0 # zero counter
movi r4,0 # zero sum
loop:
beq r2,r3,loop_end
ldw r6,0(r7) # get value
add r4,r4,r6 # add to sum
addi r2,r2,
addi r7,r7,
br loop
