mirror of
https://github.com/rzzzwilson/pymlac.git
synced 2025-06-10 09:32:41 +00:00
Passes 1 & 2 now seem OK, worry about code generation
This commit is contained in:
Ross Wilson
parent
59793e3627
commit
f82bb11491
243
pyasm/pyasm
243
pyasm/pyasm
@ -71,13 +71,17 @@ CurrentLineNumber = None
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Undefined = None
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# buffer for blocked code
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BlockBuffer = []
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BlockMaxSize = 255
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BlockBuffer = bytearray()
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BlockBufferStart = None
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######
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# Mostly constant stuff
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######
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# mask for 16bit values
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WordMask = 0xFFFF
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# the output PTP filename extension
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PTPExtension = '.ptp'
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@ -88,7 +92,7 @@ ListFileExtension = '.lst'
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WordBits = 16
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# number of bytes in the 'zero' leader
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ZeroLeaderSize = 16
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ZeroLeaderSize = 32
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# address states, AYES = address required,
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# ANO = address NOT required
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@ -341,79 +345,109 @@ def usage(msg=None):
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def error(msg):
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"""Print a syntax error and abort."""
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lnum = CurrentLineNumber if CurrentLineNumber else 1
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line = CurrentLine if CurrentLine else ''
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print('-' * 80)
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print("%04d: %s" % (CurrentLineNumber, CurrentLine))
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print("%04d: %s" % (lnum, line))
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print(msg)
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print('-' * 80)
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sys.exit(10)
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def emit_byte(byte):
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"""Emit one byte to the output file.
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def write_byte(byte):
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"""Write one byte into the output code file.
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Write only the low 8 bits of 'byte'.
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"""
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print('write_byte: byte=%04o' % byte)
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OutputFileHandle.write(chr(byte & 0xFF))
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def emit_word(word):
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def write_word(word):
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"""Emit a 16-bit word to the output file."""
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emit_byte(word >> 8)
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emit_byte(word)
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write_byte(word >> 8)
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write_byte(word)
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def emit_start(address):
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"""Emit the start block."""
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def write_start(address):
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"""Write the start block."""
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emit_byte(1) # one word block
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emit_word(address)
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write_block() # emit any code accumulated
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start_block(address)
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write_block()
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def emit_loader():
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def write_leader():
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"""Write the papertape leader."""
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for _ in range(ZeroLeaderSize):
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write_byte(0)
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def write_block_loader():
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"""Emit the block loader prefix code."""
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for _ in range(ZeroLeaderSize):
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emit_byte(0)
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write_leader()
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for word in BlockLoader:
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emit_word(word)
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write_word(word)
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for _ in range(ZeroLeaderSize):
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emit_byte(0)
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write_leader()
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def start_block(addr):
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"""Prepare next block to start at 'addr'"""
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BlockBufferStart = addr
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global BlockBuffer, BlockBufferStart
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def emit_block():
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"""Emit the current code block and reset the buffer."""
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BlockBuffer = []
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BlockBufferStart = addr
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print('start_block: BlockBufferStart set to %s' % str(BlockBufferStart))
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def emit_word(word):
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"""Put a word into the code block buffer.
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Write buffer out if full.
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"""
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code_block_size = len(BlockBuffer)
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if code_block_size >= BlockMaxSize:
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write_block()
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start_block(Dot)
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BlockBuffer.append(word)
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def write_block():
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"""Write the current code block and reset the buffer."""
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global BlockBuffer, BlockBufferStart
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# emit the block size and load address
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code_block_size = len(BlockBuffer)
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emit_byte(code_block_size)
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for v in BlockBuffer:
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emit_word(v)
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print('write_block: code_block_size=%d, BlockBufferStart=%s'
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% (code_block_size, str(BlockBufferStart)))
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if code_block_size == 0:
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# block buffer is empty, do nothing
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return
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# emit the block & calculate checksum as we go
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# emit the block size and load address
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write_byte(code_block_size)
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write_word(BlockBufferStart)
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for word in BlockBuffer:
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write_word(word)
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# calculate checksum
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checksum = 0
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for word in BlockBuffer:
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checksum += word
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if checksum and ~WordMask:
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++checksum
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checksum &= WordMask
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emit_word(word)
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write_word(word)
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# emit the block checksum
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emit_word(checksum)
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write_word(checksum)
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# reset the code buffer
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BlockBuffer = []
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if BlockBufferStart:
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BlockBufferStart += code_block_size
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else:
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BlockBufferStart = None
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BlockBufferStart = None
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def write_list(code, addr, lnum, line):
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"""Generate one line of listing file.
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@ -441,8 +475,6 @@ def eval_expr(expr):
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Returns 'None' if there is no valid expression.
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"""
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print('eval_expr: expr=%s' % str(expr))
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global Undefined
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# if no expression, do nothing
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@ -457,15 +489,17 @@ def eval_expr(expr):
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# evaluate the expression
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try:
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result = eval(expr, globs)
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except TypeError as e:
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error("ORG pseudo-opcode expression contains unsatisfied references")
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return None
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except NameError as e:
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# except TypeError as e:
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# error("ORG pseudo-opcode expression contains unsatisfied references")
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# return None
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except (TypeError, 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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error("ORG pseudo-opcode expression has '%s' undefined" % Undefined)
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error("ORG pseudo-opcode expression has an error")
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raise NameError("ORG pseudo-opcode expression has '%s' undefined" % Undefined)
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# error("ORG pseudo-opcode expression has '%s' undefined" % Undefined)
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raise NameError("ORG pseudo-opcode expression has an error")
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# error("ORG pseudo-opcode expression has an error")
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return result
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@ -487,8 +521,9 @@ def pass_1(lines):
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Returns False if there was an error.
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"""
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global StartAddress
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global Dot, CurrentLineNumber, CurrentLine, SymTable, SymTableLine
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global Dot, StartAddress
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global CurrentLineNumber, CurrentLine
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global SymTable, SymTableLine
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# initialize things
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Dot = None
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@ -508,9 +543,11 @@ def pass_1(lines):
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# we have an opcode, so code might be generated
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if opcode == 'ORG':
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if not addr or eval_expr(addr) is None:
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error("ORG pseudo-op has bad address")
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error("ORG pseudo-op has a bad address")
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return False
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Dot = eval_expr(addr)
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if label:
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error("ORG pseudo-op must not have a label")
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elif opcode == 'EQU':
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# no code, but we define a label
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@ -518,14 +555,14 @@ def pass_1(lines):
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error("EQU pseudo-op must have a label")
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return False
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if not addr or eval_expr(addr) is None:
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error("EQU pseudo-op has bad value")
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error("EQU pseudo-op has a bad value")
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return False
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define_label(label, eval_expr(addr), lnum)
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elif opcode == 'BSS':
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# no code, but Dot moves
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if not addr or eval_expr(addr) is None:
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error("BSS pseudo-op has bad value")
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error("BSS pseudo-op has a bad value")
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return False
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if label:
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define_label(label, Dot, lnum)
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@ -534,14 +571,16 @@ def pass_1(lines):
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elif opcode == 'DATA':
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# a single data word
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if not addr or eval_expr(addr) is None:
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error("BSS pseudo-op has bad value")
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error("BSS pseudo-op has a bad value")
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return False
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if label:
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define_label(label, Dot, lnum)
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Dot += 1
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elif opcode == 'ASCII':
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# an ASCII string, packed two bytes/word
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# ASCII string, pack two bytes/word, maybe zero byte fill at end
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print('ASCII: addr=%' % str(addr))
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# TODO worry if string has delimiting quotes
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ascii_len = len(addr)
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ascii_words = ascii_len / 2
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if ascii_len % 2:
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@ -550,7 +589,12 @@ def pass_1(lines):
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elif opcode == 'END':
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# get the (optional) start address
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StartAddress = eval_expr(addr)
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StartAddress = None
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if addr:
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StartAddress = eval_expr(addr)
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if StartAddress is None:
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error("END pseudo-op has a bad address")
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return False
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return True
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else:
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@ -569,12 +613,17 @@ def pass_1(lines):
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return True
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def pass_2(lines):
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"""Perform the second pass of the assembly."""
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"""Perform the second pass of the assembly.
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global Dot, CurrentLineNumber, CurrentLine
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Very similar to pass_1(), but we:
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. don't define labels, that was done in pass_1()
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. check that any pass_2 labels haven't changed value
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"""
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global Dot, StartAddress, CurrentLineNumber, CurrentLine
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# punch the zero leader and ptr/tty loader
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emit_loader()
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write_block_loader()
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# for each line in the file
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Dot = None
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@ -585,45 +634,60 @@ def pass_2(lines):
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# get line fields
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(label, opcode, indirect, addr) = split_fields(line)
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print('#####: label=%s, opcode=%s, indirect=%s, addr=%s'
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print('pass_2: label=%s, opcode=%s, indirect=%s, addr=%s'
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% (str(label), str(opcode), str(indirect), str(addr)))
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if opcode:
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# we have an opcode, so code might be generated
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if opcode == 'ORG':
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if not addr or eval_expr(addr) is None:
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error("ORG pseudo-op has bad address")
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if label:
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error("ORG pseudo-op may not have a label")
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return False
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emit_block() # punch any accumulated code
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if not addr or eval_expr(addr) is None:
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error("ORG pseudo-op has a bad address")
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return False
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write_block() # write any code accumulated so far
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Dot = eval_expr(addr)
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print('ORG: Dot set to %06o' % Dot)
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start_block(Dot)
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elif opcode == 'EQU':
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# no code, but we define a label
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# no code, but we must have a label
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if not label:
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error("EQU pseudo-op must have a label")
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return False
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if not addr or eval_expr(addr) is None:
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error("EQU pseudo-op has bad value")
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error("EQU pseudo-op has a bad value")
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return False
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value = eval_expr(addr)
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# check EQU value unchanged
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try:
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old_value = SymTable[label]
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value = eval_expr(addr)
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if value != old_value:
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error("EQU value in '%s' has changed,\n"
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"was %06o, is now %06o"
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% (old_value, value))
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except KeyError:
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error("EQU label '%s' not defined in second pass!?"
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error("EQU label '%s' wasn't defined in first pass!?"
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% label)
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elif opcode == 'BSS':
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# no code, but Dot moves
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if not addr or eval_expr(addr) is None:
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error("BSS pseudo-op has bad value")
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return False
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emit_block() # punch any accumalated code
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Dot += eval_expr(addr)
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value = eval_expr(addr)
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if label:
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try:
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old_value = SymTable[label]
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if value != old_value:
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error("BSS value in has changed, "
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"was %06o, is now %06o"
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% (old_value, value))
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except KeyError:
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error("BSS label '%s' wasn't defined in first pass!?"
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% label)
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write_block() # write any code accumulated so far
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Dot += value
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start_block(Dot)
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elif opcode == 'DATA':
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@ -631,7 +695,18 @@ def pass_2(lines):
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if not addr or eval_expr(addr) is None:
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error("BSS pseudo-op has bad value")
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return False
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emit_word(eval_expr(addr))
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value = eval_expr(addr)
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if label:
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try:
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old_value = SymTable[label]
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if value != old_value:
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error("BSS value has changed, "
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"was %06o, is now %06o"
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% (old_value, value))
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except KeyError:
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error("DATA label '%s' wasn't defined in first pass!?"
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% label)
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emit_word(value)
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Dot += 1
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elif opcode == 'ASCII':
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@ -645,27 +720,27 @@ def pass_2(lines):
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elif opcode == 'END':
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# get optional start address
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global StartAddress
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start_address = eval_expr(addr)
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if start_address != StartAddress:
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print('start_address=%s, StartAddress=%s' % (str(start_address), str(StartAddress)))
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error("Pass 2 start address is different from pass 1, was %06o but now %06o"
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% (StartAddress, start_address))
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StartAddress = start_address
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return True
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StartAddress = None
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if addr:
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# we have the optional start address
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start_address = eval_expr(addr)
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if start_address != StartAddress:
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error("Pass 2 start address is different from pass 1, "
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"was %06o but now %06o"
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% (StartAddress, start_address))
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StartAddress = start_address
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break # end of pass
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else:
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# actual machine instruction!
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# if label, check value unchanged
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if label:
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if not label in SymTable:
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error("Label '%s' not defined in pass 2!?" % label)
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error("Label '%s' not defined in pass 1!?" % label)
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old_dot = SymTable[label]
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if old_dot != Dot:
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error("Label '%s' has different value in pass 2.\n"
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error("Start address has different value in pass 2.\n"
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"Was %06o, now %06o"
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% (label. old_dot, Dot))
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% (old_dot, Dot))
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gen_code(lnum, line, label, label, opcode, indirect, addr)
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Dot += 1
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@ -674,13 +749,15 @@ def pass_2(lines):
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if label in SymTable:
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dot = SymTable[label]
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if dot != Dot:
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error("Second pass, line '%s'\n"
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"Label '%s' has value %06o, was %06o in first pass"
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% (line, label, Dot, dor))
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error("Label '%s' has value %06o, was %06o in first pass"
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% (label, Dot, dot))
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# punch the final block of code and optional start address
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emit_block()
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emit_start()
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# write the final block of code and optional start address
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write_block()
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if StartAddress is not None:
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print('write_start(%06o)' % StartAddress)
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write_start(StartAddress)
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write_leader()
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# check nothing after END
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if lnum - 1 > len(lines):
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@ -862,8 +939,9 @@ def assemble_file():
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print('asm_lines=\n%s' % '\n'.join(asm_lines))
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if pass_1(asm_lines):
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print('SymTable=%s' % str(SymTable))
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print('After pass_1(), SymTable=%s' % str(SymTable))
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pass_2(asm_lines)
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print('After pass_2(), SymTable=%s' % str(SymTable))
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def main():
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"""The assembler."""
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@ -922,6 +1000,7 @@ def main():
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if __name__ == '__main__':
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main()
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#/******************************************************************************
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# Name : emitblock()
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#Description : Emit the code for the current block.
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