Add source code of "fibonacci" testbench

Author: vacantron

build/Fibonacci.elf

@@ -0,0 +1,43 @@
+fib:
+	li		a5,1
+	bleu	a0,a5,.L3
+	addi	sp,sp,-16
+	sw		ra,12(sp)
+	sw		s0,8(sp)
+	sw		s1,4(sp)
+	mv		s0,a0
+	addi	a0,a0,-1
+	la		t0,fib
+	jalr	ra,0(t0)
+	mv		s1,a0
+	addi	a0,s0,-2
+	la	 	t0,fib
+	jalr	ra,0(t0)
+	add		a0,s1,a0
+	lw		ra,12(sp)
+	lw		s0,8(sp)
+	lw		s1,4(sp)
+	addi	sp,sp,16
+	jr		ra
+.L3:
+	li		a0,1
+	ret
+.LC0:
+	.string	"%d\n"
+	.text
+	.align	1
+	.globl	main
+	.type	main, @function
+main:
+	addi	sp,sp,-16
+	sw		ra,12(sp)
+	li		a0,42
+	call	fib
+	mv		a1,a0
+	lui		a0,%hi(.LC0)
+	addi	a0,a0,%lo(.LC0)
+	call	printf
+	li		a0,0
+	lw		ra,12(sp)
+	addi	sp,sp,16
+	jr		ra