先展示8051的：
以下是一个简单的 8051 单片机模拟器的 Python 代码示例，它可以模拟 8051 的基本指令集、中断、IO 端口等功能。
- class CPU:
- def __init__(self):
- self.A = 0x00 # Accumulator
- self.PSW = 0x00 # Program status word
- self.DPTR = 0x0000 # Data pointer
- self.PC = 0x0000 # Program counter
- self.IE = False # Interrupt enable flag
- self.IP = 0x00 # Interrupt priority
- def reset(self):
- self.A = 0x00
- self.PSW = 0x00
- self.DPTR = 0x0000
- self.PC = 0x0000
- self.IE = False
- self.IP = 0x00
- def fetch(self, mem):
- instr = mem[self.PC]
- self.PC += 1
- return instr
- def decode(self, instr):
- op = (instr >> 3) & 0x1F
- reg = instr & 0x07
- return op, reg
- def execute(self, op, reg, mem):
- if op == 0x00: # NOP
- pass
- elif op == 0x01: # AJMP
- addr = (self.PC & 0xF800) | (reg << 1)
- self.PC = addr
- elif op == 0x02: # LJMP
- addr_hi = mem[self.PC]
- addr_lo = mem[self.PC+1]
- self.PC = (addr_hi << 8) | addr_lo
- # ... more instructions ...
- def interrupt(self, mem, int_num):
- self.IE = False
- self.IP = int_num
- self.PSW = (self.PSW & 0xCF) | ((int_num & 0x03) << 4)
- mem[0x03] = self.PC & 0xFF
- mem[0x02] = self.PC >> 8
- self.PC = int_num * 8 + 3
- def run(self, mem):
- while True:
- instr = self.fetch(mem)
- op, reg = self.decode(instr)
- self.execute(op, reg, mem)
- if self.PC == 0xFFFF:
- break
再展示AVR的：
以下是一个简单的 AVR 单片机模拟器的 Python 代码示例，它可以模拟 AVR 的基本指令集、中断、IO 端口等功能。
- class CPU:
- def __init__(self):
- self.R = [0] * 32 # General purpose registers
- self.PC = 0x0000 # Program counter
- self.SREG = 0x00 # Status register
- self.IE = False # Interrupt enable flag
- self.INT1 = False # Interrupt 1 flag
- self.INT2 = False # Interrupt 2 flag
- def reset(self):
- self.R = [0] * 32
- self.PC = 0x0000
- self.SREG = 0x00
- self.IE = False
- self.INT1 = False
- self.INT2 = False
- def fetch(self, mem):
- instr = mem[self.PC]
- self.PC += 1
- return instr
- def decode(self, instr):
- op = (instr >> 26) & 0x3F
- rd = (instr >> 21) & 0x1F
- rr = (instr >> 16) & 0x1F
- k = instr & 0xFFFF
- return op, rd, rr, k
- def execute(self, op, rd, rr, k, mem):
- if op == 0x00: # NOP
- pass
- elif op == 0x01: # ADD Rd, Rr
- res = self.R[rd] + self.R[rr]
- self.R[rd] = res & 0xFF
- self.SREG = (self.SREG & 0xFD) | ((res >> 8) & 0x02)
- if res & 0x100:
- self.SREG |= 0x01
- if self.R[rd] == 0:
- self.SREG |= 0x02
- elif op == 0x02: # SUB Rd, Rr
- res = self.R[rd] - self.R[rr]
- self.R[rd] = res & 0xFF
- self.SREG = (self.SREG & 0xFD) | ((res >> 8) & 0x02)
- if res & 0x100:
- self.SREG |= 0x01
- if self.R[rd] == 0:
- self.SREG |= 0x02
- # ... more instructions ...
- def interrupt(self, mem, int_num):
- self.IE = False
- self.PC = int_num * 4
- self.R[31] = self.SREG
- self.SREG |= (int_num << 3)
- mem[0x005E] = self.PC & 0xFF
- mem[0x005F] = self.PC >> 8
- def run(self, mem):
- while True:
- instr = self.fetch(mem)
- op, rd, rr, k = self.decode(instr)
- self.execute(op, rd, rr, k, mem)
- if self.PC == 0xFFFF:
- break
- if self.IE and self.INT1:
- self.interrupt(mem, 1)
- if self.IE and self.INT2:
- self.interrupt(mem, 2)
- class Memory:
- def __init__(self):
- self.sram = [0] * 1024 # SRAM
- self.io = [0] * 32 # IO registers
- def read(self, addr):
- if addr < 0x0200:
- return self.sram[addr]
- elif addr < 0x0400:
- return self.io[addr - 0x0200]
- elif addr < 0x1000:
- return self.sram[addr]
- else:
- raise Exception("Invalid address")
- def write(self, addr, value):
- if addr < 0x0200:
- self.sram[addr] = value
- elif addr < 0x0400:
- self.io[addr - 0x0200] = value
- elif addr < 0x1000:
- self.sram[addr] = value
- else:
- raise Exception("Invalid address")
将 CPU 和内存模拟器组合在一起，可以实现一个简单的 AVR 单片机模拟器。然而，需要注意的是，这只是一个基础的模拟器，不能实现复杂的芯片功能和外设操作。实际上，现有的 AVR 模拟器通常还包含更多的功能，如调试器、仿真外设等。
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