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198
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1 import re, sys, argparse
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191
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2 import pyyacc
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3 from ppci import Token, CompilerError, SourceLocation
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199
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4 from target import Target
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200
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5 from asmnodes import ALabel, AInstruction, ABinop, AUnop, ASymbol, ANumber
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159
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6
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7 def tokenize(s):
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8 """
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9 Tokenizer, generates an iterator that
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10 returns tokens!
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11
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12 This GREAT example was taken from python re doc page!
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13 """
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14 tok_spec = [
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15 ('REAL', r'\d+\.\d+'),
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16 ('HEXNUMBER', r'0x[\da-fA-F]+'),
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17 ('NUMBER', r'\d+'),
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18 ('ID', r'[A-Za-z][A-Za-z\d_]*'),
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19 ('SKIP', r'[ \t]'),
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191
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20 ('LEESTEKEN', r':=|[\.,=:\-+*\[\]/\(\)]|>=|<=|<>|>|<'),
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198
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21 ('STRING', r"'.*?'"),
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22 ('COMMENT', r";.*")
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159
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23 ]
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24 tok_re = '|'.join('(?P<%s>%s)' % pair for pair in tok_spec)
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25 gettok = re.compile(tok_re).match
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26 line = 1
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27 pos = line_start = 0
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28 mo = gettok(s)
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29 while mo is not None:
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30 typ = mo.lastgroup
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31 val = mo.group(typ)
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32 if typ == 'NEWLINE':
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33 line_start = pos
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34 line += 1
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35 elif typ != 'SKIP':
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199
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36 if typ == 'LEESTEKEN':
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37 typ = val
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38 elif typ == 'NUMBER':
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39 val = int(val)
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40 elif typ == 'HEXNUMBER':
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41 val = int(val[2:], 16)
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42 typ = 'NUMBER'
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43 elif typ == 'REAL':
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44 val = float(val)
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45 elif typ == 'STRING':
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46 val = val[1:-1]
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47 col = mo.start() - line_start
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48 loc = SourceLocation(line, col, 0) # TODO retrieve length?
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49 yield Token(typ, val, loc)
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50 pos = mo.end()
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51 mo = gettok(s, pos)
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52 if pos != len(s):
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53 col = pos - line_start
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54 loc = SourceLocation(line, col, 0)
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55 raise CompilerError('Unexpected character {0}'.format(s[pos]), loc)
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159
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56
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57 class Lexer:
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58 def __init__(self, src):
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59 self.tokens = tokenize(src)
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60 self.curTok = self.tokens.__next__()
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61 def eat(self):
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62 t = self.curTok
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63 self.curTok = self.tokens.__next__()
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64 return t
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65 @property
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66 def Peak(self):
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67 return self.curTok
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68
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195
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69
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70 class Assembler:
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199
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71 def __init__(self, target=None):
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72 self.target = target
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73 self.restart()
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191
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74 # Construct a parser given a grammar:
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75 ident = lambda x: x # Identity helper function
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76 g = pyyacc.Grammar(['ID', 'NUMBER', ',', '[', ']', ':', '+', '-', '*', pyyacc.EPS, 'COMMENT'])
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77 g.add_production('asmline', ['asmline2'])
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78 g.add_production('asmline', ['asmline2', 'COMMENT'])
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79 g.add_production('asmline2', ['label', 'instruction'])
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80 g.add_production('asmline2', ['instruction'])
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81 g.add_production('asmline2', ['label'])
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82 g.add_production('asmline2', [])
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83 g.add_production('optcomment', [])
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84 g.add_production('optcomment', ['COMMENT'])
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85 g.add_production('label', ['ID', ':'], self.p_label)
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86 g.add_production('instruction', ['opcode', 'operands'], self.p_ins_1)
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87 g.add_production('instruction', ['opcode'], self.p_ins_2)
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88 g.add_production('opcode', ['ID'], ident)
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89 g.add_production('operands', ['operand'], self.p_operands_1)
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90 g.add_production('operands', ['operands', ',', 'operand'], self.p_operands_2)
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91 g.add_production('operand', ['expression'], ident)
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92 g.add_production('operand', ['[', 'expression', ']'], self.p_mem_op)
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93 g.add_production('expression', ['term'], ident)
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94 g.add_production('expression', ['expression', 'addop', 'term'], self.p_binop)
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95 g.add_production('addop', ['-'], ident)
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96 g.add_production('addop', ['+'], ident)
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97 g.add_production('mulop', ['*'], ident)
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98 g.add_production('term', ['factor'], ident)
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99 g.add_production('term', ['term', 'mulop', 'factor'], self.p_binop)
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100 g.add_production('factor', ['ID'], lambda name: ASymbol(name))
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101 g.add_production('factor', ['NUMBER'], lambda num: ANumber(int(num)))
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102 g.start_symbol = 'asmline'
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103 self.p = g.genParser()
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104
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105 # Parser handlers:
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106 def p_ins_1(self, opc, ops):
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107 ins = AInstruction(opc, ops)
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108 self.emit(ins)
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109 def p_ins_2(self, opc):
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110 self.p_ins_1(opc, [])
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111 def p_operands_1(self, op1):
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112 return [op1]
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113 def p_operands_2(self, ops, comma, op2):
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114 assert type(ops) is list
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115 ops.append(op2)
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116 return ops
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117 def p_mem_op(self, brace_open, exp, brace_close):
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118 return AUnop('[]', exp)
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119 def p_label(self, lname, cn):
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120 lab = ALabel(lname)
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121 self.emit(lab)
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122 def p_binop(self, exp1, op, exp2):
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123 return ABinop(op, exp1, exp2)
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124
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196
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125 # Top level interface:
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126 def restart(self):
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200
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127 self.output = []
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128 self.binout = bytearray()
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129 self.current_section = '.text'
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130
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131 def emit(self, a):
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132 """ Emit a parsed instruction """
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133 self.output.append(a)
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134 # Determine the bit pattern from a lookup table:
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135 # TODO
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136
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137 def parse_line(self, line):
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138 """ Parse line into asm AST """
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139 tokens = tokenize(line)
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140 self.p.parse(tokens)
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191
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141
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142 def assemble(self, asmsrc):
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143 """ Assemble this source snippet """
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144 for line in asmsrc.split('\n'):
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145 self.assemble_line(line)
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146 self.back_patch()
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159
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147
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196
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148 def assemble_line(self, line):
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149 """
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150 Assemble a single source line.
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151 Do not take newlines into account
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152 """
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196
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153 self.parse_line(line)
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154 self.assemble_aast()
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191
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155
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198
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156 def assemble_aast(self):
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191
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157 """ Assemble a parsed asm line """
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199
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158 # TODO
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159 if not self.target:
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160 raise CompilerError('Cannot assemble without target')
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161 while self.output:
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200
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162 vi = self.output.pop(0)
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203
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163 if type(vi) is AInstruction:
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164 ri = self.target.mapInstruction(vi)
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165 b = ri.encode()
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166 assert type(b) is bytes
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167 self.binout.extend(b)
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191
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168
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169 def back_patch(self):
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170 """ Fix references to earlier labels """
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171 pass
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191
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172
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196
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173
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174 if __name__ == '__main__':
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175 # When run as main file, try to grab command line arguments:
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176 parser = argparse.ArgumentParser(description="Assembler")
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177 parser.add_argument('sourcefile', type=argparse.FileType('r'), help='the source file to assemble')
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178 args = parser.parse_args()
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179 a = Assembler()
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180 obj = a.assemble(args.sourcefile.read())
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181
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