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122 lines
4.1 KiB
Python
122 lines
4.1 KiB
Python
"""
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Programming Language for 6502/6510 microprocessors, codename 'Sick'
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This is the assembly code generator (from the parse tree)
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Written by Irmen de Jong (irmen@razorvine.net) - license: GNU GPL 3.0
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"""
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import contextlib
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import math
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from typing import Set, Callable
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from ..datatypes import FLOAT_MAX_POSITIVE, FLOAT_MAX_NEGATIVE
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from ..plyparse import Scope
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from ..compile import Zeropage
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class CodeError(Exception):
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pass
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def to_hex(number: int) -> str:
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# 0..15 -> "0".."15"
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# 16..255 -> "$10".."$ff"
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# 256..65536 -> "$0100".."$ffff"
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assert type(number) is int
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if number is None:
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raise ValueError("number")
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if 0 <= number < 16:
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return str(number)
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if 0 <= number < 0x100:
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return "${:02x}".format(number)
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if 0 <= number < 0x10000:
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return "${:04x}".format(number)
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raise OverflowError(number)
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def to_mflpt5(number: float) -> bytearray:
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# algorithm here https://sourceforge.net/p/acme-crossass/code-0/62/tree/trunk/ACME_Lib/cbm/mflpt.a
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number = float(number)
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if number < FLOAT_MAX_NEGATIVE or number > FLOAT_MAX_POSITIVE:
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raise OverflowError("floating point number out of 5-byte mflpt range", number)
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if number == 0.0:
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return bytearray([0, 0, 0, 0, 0])
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if number < 0.0:
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sign = 0x80000000
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number = -number
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else:
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sign = 0x00000000
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mant, exp = math.frexp(number)
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exp += 128
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if exp < 1:
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# underflow, use zero instead
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return bytearray([0, 0, 0, 0, 0])
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if exp > 255:
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raise OverflowError("floating point number out of 5-byte mflpt range", number)
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mant = sign | int(mant * 0x100000000) & 0x7fffffff
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return bytearray([exp]) + int.to_bytes(mant, 4, "big")
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def mflpt5_to_float(mflpt: bytearray) -> float:
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# algorithm here https://sourceforge.net/p/acme-crossass/code-0/62/tree/trunk/ACME_Lib/cbm/mflpt.a
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if mflpt == bytearray([0, 0, 0, 0, 0]):
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return 0.0
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exp = mflpt[0] - 128
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sign = mflpt[1] & 0x80
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number = 0x80000000 | int.from_bytes(mflpt[1:], "big")
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number = float(number) * 2**exp / 0x100000000
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return -number if sign else number
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@contextlib.contextmanager
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def preserving_registers(registers: Set[str], scope: Scope, out: Callable, loads_a_within: bool=False, force_preserve: bool=False):
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# this sometimes clobbers a ZP scratch register and is therefore NOT safe to use in interrupts
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# see http://6502.org/tutorials/register_preservation.html
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if not scope.save_registers and not force_preserve:
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yield
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return
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if registers == {'A'}:
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out("\t\tpha")
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yield
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out("\t\tpla")
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elif registers:
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if not loads_a_within:
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out("\t\tsta ${:02x}".format(Zeropage.SCRATCH_B2))
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if 'A' in registers:
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out("\t\tpha")
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if 'X' in registers:
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out("\t\ttxa\n\t\tpha")
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if 'Y' in registers:
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out("\t\ttya\n\t\tpha")
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if not loads_a_within:
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out("\t\tlda ${:02x}".format(Zeropage.SCRATCH_B2))
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yield
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if 'X' in registers and 'Y' in registers:
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if 'A' not in registers:
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out("\t\tsta ${:02x}".format(Zeropage.SCRATCH_B2))
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out("\t\tpla\n\t\ttay")
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out("\t\tpla\n\t\ttax")
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out("\t\tlda ${:02x}".format(Zeropage.SCRATCH_B2))
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else:
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out("\t\tpla\n\t\ttay")
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out("\t\tpla\n\t\ttax")
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else:
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if 'Y' in registers:
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if 'A' not in registers:
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out("\t\tsta ${:02x}".format(Zeropage.SCRATCH_B2))
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out("\t\tpla\n\t\ttay")
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out("\t\tlda ${:02x}".format(Zeropage.SCRATCH_B2))
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else:
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out("\t\tpla\n\t\ttay")
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if 'X' in registers:
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if 'A' not in registers:
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out("\t\tsta ${:02x}".format(Zeropage.SCRATCH_B2))
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out("\t\tpla\n\t\ttax")
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out("\t\tlda ${:02x}".format(Zeropage.SCRATCH_B2))
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else:
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out("\t\tpla\n\t\ttax")
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if 'A' in registers:
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out("\t\tpla")
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else:
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yield
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