mirror of
https://github.com/WangXuan95/USTC-RVSoC.git
synced 2025-01-30 23:02:55 +08:00
54 lines
1.8 KiB
ArmAsm
54 lines
1.8 KiB
ArmAsm
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.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, 6 # t0 = 6
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jal ra, fibonacci_recursive
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xori a1, t1, 0 # 计算完成，结果在t1中，闲着没事干把它放到a1里好了
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jal zero, program_end # 跳到死循环程序
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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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program_end:
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jal zero, program_end # infinity loop
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