mirror of
https://github.com/rzzzwilson/pymlac.git
synced 2025-06-10 09:32:41 +00:00
Almost finished, need to assemble opcode
This commit is contained in:
Ross Wilson
parent
01d2d7b60d
commit
86a6f7bb14
150
pyasm/pyasm
150
pyasm/pyasm
@ -64,6 +64,9 @@ BackpatchList = []
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CurrentLine = None
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CurrentLineNumber = None
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# Any undefined label
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Undefined = None
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######
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# Mostly constant stuff
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######
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@ -119,9 +122,11 @@ def write_list(code, addr, lnum, line):
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code_str = '%06o' % code if code else ''
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addr_str = '%04o' % addr if addr else ''
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lnum_str = '%04d:' % lnum if lnum else ''
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line_str = '%s' % line if line else ''
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ListFileHandle.write('%6s %4s %04d: %s\n'
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% (code_str, addr_str, lnum, line))
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ListFileHandle.write('%6s %4s %s %s\n'
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% (code_str, addr_str, lnum_str, line_str))
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ListFileHandle.flush()
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def eval_expression(expr, dot):
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@ -131,12 +136,27 @@ def eval_expression(expr, dot):
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dot current code address (the "." symbol value)
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Valid expressions are:
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# <expr> ::= <string> | <numeric_expression>
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# <string> ::= ('|") <characters> ('|")
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<expr> ::= <string> | <numeric_expression>
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<string> ::= ('|") <characters> ('|")
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<numeric_expression> ::= (<numeric_const>|<name_const>|".") [ (+|-) <numeric_expression> ]
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<name_const> ::= <name_characters>
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"""
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global Undefined
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print('eval_expression: expr=%s' % expr)
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# if no expression, do nothing
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if expr is None:
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return None
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# if expression is a string, return an iterable of ASCII values
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if expr[0] in "'\"":
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delim = expr[0]
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if expr[-1] != delim:
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error("Badly formed string value: '%s'" % expr)
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return expr[1:-1]
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# replace any "." value with "dot" defined in the symbol table
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expr = string.replace(expr, '.', 'dot')
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expr = expr.upper()
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@ -149,6 +169,11 @@ def eval_expression(expr, dot):
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except TypeError as e:
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error('ORG pseudo-opcode expression contains unsatisfied references\n'
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'%d: %s' % (CurrentLineNumber, CurrentLine))
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except NameError as e:
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Undefined = e.message
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if 'is not defined' in e.message:
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Undefined = e.message[len("name '"):-len("' is not defined")]
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raise
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return result
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@ -211,8 +236,11 @@ def assemble_oblock(oblock):
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if label:
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error('%d: %s\nORG opcode may not have a label'
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% (lnum, line))
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address = eval_expression(addr, address)
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code = None
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try:
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address = eval_expression(addr, address)
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except NameError as e:
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error("%d: %s\nName '%s' is undefined"
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% (lnum, line, Undefined))
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cblock = [address, []]
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write_list(None, None, lnum, line)
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continue
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@ -220,20 +248,46 @@ def assemble_oblock(oblock):
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# END pseudo-op, terminate assembly
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start_addr = None
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if addr:
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start_addr = eval_expression(addr, address)
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try:
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start_addr = eval_expression(addr, address)
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except NameError as e:
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error("%d: %s\nName '%s' is undefined"
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% (lnum, line, undefined))
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write_list(None, start_addr, lnum, line)
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return cblock
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elif opcode == 'EQU':
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if label is None:
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error('%d: %s\nEQU opcode missing a label'
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% (lnum, line))
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value = eval_expression(addr, None)
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try:
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value = eval_expression(addr, None)
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except NameError as e:
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error("%d: %s\nName '%s' is undefined"
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% (lnum, line, Undefined))
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define_label(label, value, lnum)
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write_list(None, None, lnum, line)
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continue
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elif opcode == 'DATA':
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try:
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value = eval_expression(addr, address)
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except NameError as e:
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error("%d: %s\nName '%s' is undefined"
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% (lnum, line, Undefined))
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ln = lnum
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li = line
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if isinstance(value, basestring):
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# ASCII constant
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for ch in value:
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write_list(ord(ch), address, ln, li)
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address += 1
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ln = None
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li = None
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else:
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write_list(value, address, lnum, line)
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address += 1
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else:
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code = assemble_line(lnum, opcode, addr)
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cblock[1].append(code)
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cblock[1].append((code, addr))
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write_list(code, address, lnum, line)
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if label:
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define_label(label, address, lnum)
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@ -243,6 +297,8 @@ def assemble_oblock(oblock):
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define_label(label, address, lnum)
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write_list(None, None, lnum, line)
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return cblock
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def assemble_org_blocks(blocks):
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"""Assemble org blocks producing a code blocks list."""
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@ -304,7 +360,7 @@ def split_fields(line):
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if ndx == -1:
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error('Unbalanced string delimiter:\n'
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'%d: %s' % (CurrentLineNumber, CurrentLine))
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address = remainder[:ndx].strip()
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address = '"' + remainder[:ndx].strip() + '"'
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remainder = remainder[ndx+1:].strip()
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else:
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# strip off any comment
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@ -354,6 +410,72 @@ def split_orgs(asm_lines):
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return result
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def check_org_overlap(code_blocks):
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"""Check that we don't have overlapping ORG blocks."""
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# remember org block span: [(start, end), (start', end'), ...]
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block_span = []
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for cb in code_blocks:
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(address, code) = cb
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if address is None and not code:
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# empty code block, ignore
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continue
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(block_start, code) = cb
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block_end = block_start + len(code) - 1
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print('block: %06o,%06o' % (block_start, block_end))
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for (start, end) in block_span:
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print('check block: %06o,%06o' % (start, end))
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if start <= block_start <= end:
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error('ORG block at address %06o overwrites previous block at [%06o,%06o]'
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% (block_start, start, end))
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if start <= block_end <= end:
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error('ORG block at address %06o overwrites previous block at [%06o,%06o]'
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% (block_start, start, end))
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block_span.append((block_start, block_end))
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def allocate_literals(code_blocks):
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"""Allocate space for literal blocks."""
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pass
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def backpatch(code_blocks):
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"""Generate final code values, evaluate address fields.
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Returns a simplified code block list: [[address, [code, code, ...]], ...].
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"""
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print('backpatch: code_blocks=%s' % str(code_blocks))
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result = []
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for cb in code_blocks:
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print('cb=%s' % str(cb))
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(address, codes) = cb
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if address is None and not codes:
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# empty code block, ignore
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continue
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# got a code_block that has code
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dot = address
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new_code = []
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for (code, addr) in codes:
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try:
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addr_value = eval_expression(addr, dot)
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except NameError as e:
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error("Name '%s' is undefined" % Undefined)
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if addr_value:
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code |= addr_value
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new_code.append(code)
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dot += 1
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result.append([address, new_code])
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return [address, new_code]
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def assemble_file():
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"""Assemble the file and produce listing, output files."""
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@ -372,6 +494,14 @@ def assemble_file():
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print('SymTable=%s' % str(SymTable))
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print('SymTableLine=%s' % str(SymTableLine))
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# allow programmer to overlap ORG blocks
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# check_org_overlap(code_blocks)
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allocate_literals(code_blocks)
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patched_code_blocks = backpatch(code_blocks)
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print('patched_code_blocks=%s' % str(patched_code_blocks))
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def main():
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"""The assembler."""
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