Add Lab-1: Fibonacci

lab-1/Makefile

@@ -0,0 +1,27 @@
+CC	= arm-linux-gnueabihf-gcc
+CFLAGS	= -O1 -Wall
+LDFLAGS = -fno-stack-protector
+
+objects	= fibseq.o fib.o
+
+default: fibseq
+
+.PHONY: default clean
+
+fibseq: $(objects)
+	$(CC) $(LDFLAGS) -o $@ $^
+
+fib.o: fib.s
+fibseq.o: fibseq.c
+
+%.o: %.c
+	$(CC) -c $(CFLAGS) -o $@ $<
+
+%.o: %.s
+	$(CC) -c $(CFLAGS) -o $@ $<
+
+clean:
+	rm -f $(objects) fibseq
+
+qemu: fibseq
+	qemu-arm -L /usr/arm-linux-gnueabihf ./fibseq

lab-1/fib.s

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+	.syntax unified
+	.arch armv7-a
+	.text
+	.align 2
+	.thumb
+	.thumb_func
+
+	.global fibonacci
+	.type fibonacci, function
+
+fibonacci:
+	@ ADD/MODIFY CODE BELOW
+	@ PROLOG
+	push {r3, r4, r5, lr}
+
+	@ R4 = R0 - 0 (update flags)
+	@ if(R0 <= 0) goto .L3 (which returns 0)
+
+	@ Compare R4 wtih 1
+	@ If R4 == 1 goto .L4 (which returns 1)
+
+	@ R0 = R4 - 1
+	@ Recursive call to fibonacci with R4 - 1 as parameter
+
+	@ R5 = R0
+	@ R0 = R4 - 2
+	@ Recursive call to fibonacci with R4 - 2 as parameter
+
+	@ R0 = R5 + R0 (update flags)
+
+	pop {r3, r4, r5, pc}		@EPILOG
+
+	@ END CODE MODIFICATION
+.L3:
+	mov r0, #0			@ R0 = 0
+	pop {r3, r4, r5, pc}		@ EPILOG
+
+.L4:
+	mov r0, #1			@ R0 = 1
+	pop {r3, r4, r5, pc}		@ EPILOG
+
+	.size fibonacci, .-fibonacci
+	.end

lab-1/fibseq.c

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+#include <stdio.h>
+
+extern int fibonacci(int x);
+
+int main(int argc, char **argv)
+{
+  int number=0;
+  int result=0;
+
+  printf("Please input a number:");
+  scanf("%d",&number);
+  result = fibonacci(number);   
+  printf("The fibonacci sequence at %d is: %d\n", number, result);
+}
+