mirror of
https://github.com/WangXuan95/USTC-RVSoC.git
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60 lines
2.2 KiB
ArmAsm
60 lines
2.2 KiB
ArmAsm
.org 0x0
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.global _start
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_start:
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addi zero, zero, 0x123
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addi zero, zero, 0x456
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lui sp, 0x00010
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ori sp, sp, 0x400 # stack pointer=0x400, stack size = 256 dwords
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xori t0, zero, 7 # t0 = 7
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jal ra, fibonacci_recursive # fib(7) = 21 = 0x15
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jal zero, print_result # 跳到死循环打印程序，循环打印斐波那契计算结果，应该打印的是0x15
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fibonacci_recursive: # 递归计算斐波那契数列的第n项，
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# n放在t0寄存器中
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# 结果放在t1寄存器中
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# 使用ra作为返回地址，并使用堆栈，堆栈指针为sp
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ori a0, zero, 3 # a0 = 3
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bgeu t0, a0, tag # if t0>=a0(3), jmp to tag
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ori t1, t0, 0 # t1 = t0
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jalr zero, ra, 0 # pc = ra
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tag:
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addi sp, sp, -4 # sp-=4 # push ra to stack
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sw ra, (sp) # mem[sp] = ra
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addi t0, t0, -1 # t0-=1
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addi sp, sp, -4 # sp-=4 # push t0 to stack
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sw t0, (sp) # mem[sp] = t0
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jal ra, fibonacci_recursive # fibonacci_recursive n-1
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lw t0, 0(sp) # t0=mem[sp] # pop t0 from stack
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addi sp, sp, 4 # sp+=4
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addi t0, t0, -1 # t0-=1
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addi sp, sp, -4 # sp-=4 # push t1 to stack
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sw t1, (sp) # mem[sp] = t1
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jal ra, fibonacci_recursive # fibonacci_recursive n-2
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lw t2, 0(sp) # ra=mem[sp] # pop t2 from stack
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addi sp, sp, 4 # sp+=4
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add t1, t1, t2 # t1+=t2
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lw ra, 0(sp) # ra=mem[sp] # pop ra from stack
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addi sp, sp, 4 # sp+=4
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jalr zero, ra,0 # pc = ra
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print_result: # 延时循环打印斐波那契计算结果
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or t0, zero,zero # t0 清零
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lui t0, 0x00030 # t0 寄存器的高20bit=0x00020
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sb t1, (t0) # 计算完成，结果在t1中，用USER-UART打印出来
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lui t2, 0x00c00 # t2 = 0x00800000
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big_loop:
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addi t2, t2, -1 # t2 = t2-1
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bne t2, zero, big_loop # if t2!=0, jmp to big_loop
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jal zero, print_result # 大循环结束，跳到print_result，重复打印
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