最近在做計算機體系結構與組成原理的實驗，需要寫MIPS指令系統的CPU。在測試時，人工將需要測試的指令翻譯成二進位制的編碼實在有些繁瑣，而且極易出錯，正好最近在學習python，就寫了一個實用的指令碼，來完成這個工作。

由於我們實現的CPU暫時只實現了16條指令，分別是：

add rd,rs,rt 

addu rd,rs,rt 

addi rt,rs,imm 

addiu rt,rs,imm 

sub rd,rs,rt 

subu rd,rs,rt 

nor rd,rs,rt 

xori rt,rs,imm 

clo rd, rs

clz rs,rs

slt rd,rs,rt 

sltu rd,rs,rt 

slti rt,rs,imm 

sltiu rt,rs imm 

blez rs,imm 

j target 

因此這個指令碼只涉及了這些指令的內容，以後再擴充套件吧。

下面說一下實現思路：

1、從一個檔案中讀取MIPS的彙編指令；

2、通過字串處理，然後將其各個部分進行匹配；

3、將生成的二進位制編碼寫到一個檔案中。

需要注意的是，指令應該向上邊的示例一樣，在操作符和運算元之間應該有個空格，運算元之間以逗號和若干（最好0）個空格分隔，每行寫一條指令，指令前最好沒有空字元。由於這個指令碼主要是自己用，魯棒性不是很好，見諒。

下面直接上程式碼：

import os def readfile(filename): """read and store test file""" try: fobj = open(filename, 'r') except IOError, e: print "*** file open error:", e else: lines = [] for eachLine in fobj: lines.append(eachLine) fobj.close() return lines def writefile(filename, l): """write the file with the binary""" ls = os.linesep fobj = open(filename, 'w') fobj.writelines(['%s%s' % (x, ls) for x in l]) fobj.close() print 'DONE!' def splitOandD(inst): """split the op and data""" sinst = [] for x in inst: z = x.rstrip() y = z.split(' ', 1) sinst.append(y); return sinst def numtobin(num, count): """tran a num to binary""" s = (bin(num))[2:] ss = ((count - len(s)) * '0') + s return ss def regtobin(reg): """make a regs to binary""" regs = reg.lstrip() regnum = regs[1:] if((int)(regnum) <= 31 and (int)(regnum) >= 0): regb = numtobin((int)(regnum), 5) return regb else: print "***no regs: ", regs return regb def handle(ins): """handle the strings to regular binary code""" op = (str)(ins[0]) data = (str)(ins[1]) sdata = data.lstrip() dl = sdata.split(',') if op == "add": opcode = "000000" rd = regtobin(dl[0]) rs = regtobin(dl[1]) rt = regtobin(dl[2]) func = "100000" incode = opcode+rs+rt+rd+"00000"+func elif op == "addu": opcode = "000000" rd = regtobin(dl[0]) rs = regtobin(dl[1]) rt = regtobin(dl[2]) func = "100001" incode = opcode+rs+rt+rd+"00000"+func elif op == "addi": opcode = "001000" rt = regtobin(dl[0]) rs = regtobin(dl[1]) imm = numtobin((int)(dl[2]), 16) incode = opcode + rs + rt + imm elif op == "addiu": opcode = "001001" rt = regtobin(dl[0]) rs = regtobin(dl[1]) imm = numtobin((int)(dl[2]), 16) incode = opcode + rs + rt + imm elif op == "sub": opcode = "000000" rd = regtobin(dl[0]) rs = regtobin(dl[1]) rt = regtobin(dl[2]) func = "100010" incode = opcode+rs+rt+rd+"00000"+func elif op == "subu": opcode = "000000" rd = regtobin(dl[0]) rs = regtobin(dl[1]) rt = regtobin(dl[2]) func = "100011" incode = opcode+rs+rt+rd+"00000"+func elif op == "nor": opcode = "000000" rd = regtobin(dl[0]) rs = regtobin(dl[1]) rt = regtobin(dl[2]) func = "100111" incode = opcode+rs+rt+rd+"00000"+func elif op == "xori": opcode = "001110" rt = regtobin(dl[0]) rs = regtobin(dl[1]) imm = numtobin((int)(dl[2]), 16) incode = opcode + rs + rt + imm elif op == "clo": opcode = "011100" rd = regtobin(dl[0]) rs = regtobin(dl[1]) func = "100001" incode = opcode + rs + "00000" + rd + "00000" + func elif op == "clz": opcode = "011100" rd = regtobin(dl[0]) rs = regtobin(dl[1]) func = "100000" incode = opcode + rs + "00000" + rd + "00000" + func elif op == "slt": opcode = "000000" rd = regtobin(dl[0]) rs = regtobin(dl[1]) rt = regtobin(dl[2]) func = "101010" incode = opcode+rs+rt+rd+"00000"+func elif op == "sltu": opcode = "000000" rd = regtobin(dl[0]) rs = regtobin(dl[1]) rt = regtobin(dl[2]) func = "101011" incode = opcode+rs+rt+rd+"00000"+func elif op == "slti": opcode = "001010" rt = regtobin(dl[0]) rs = regtobin(dl[1]) imm = numtobin((int)(dl[2]), 16) incode = opcode + rs + rt + imm elif op == "sltiu": opcode = "001011" rt = regtobin(dl[0]) rs = regtobin(dl[1]) imm = numtobin((int)(dl[2]), 16) incode = opcode + rs + rt + imm elif op == "blez": opcode = "000110" rs = regtobin(dl[0]) imm = numtobin((int)(dl[1]), 16) incode = opcode + rs + "00000" + imm elif op == "j": opcode = "000010" imm = numtobin((int)(dl[0]), 26) incode = opcode + imm else: print "***Not Define: ", op return incode def main(): l = readfile("i.txt") s = splitOandD(l) b = [] print s for m in s: if m != ['']: print m b.append(handle(m)) writefile("o.txt", b) if __name__ == "__main__": main()

Reference：

《Mips instruction Reference》