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https://github.com/KrisKennaway/ii-vision.git
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4251c9938f
Add a new DHGRBitmap class that efficiently represents the DHGR interleaving of the (aux, main) MemoryMap as a sequence of 28-bit integers. This allows for easily extracting the 8-bit and 12-bit subsequences representing the DHGR pixels that are influenced when storing a byte at offsets 0..3 within the interleaved (aux, main, aux, main) sequence. Since we have precomputed all of the pairwise differences between these 8- and 12-bit values, this allows us to efficiently compute the edit distances between pairs of screen bytes (and/or arrays)
204 lines
6.9 KiB
Python
204 lines
6.9 KiB
Python
"""Various representations of Apple II video display."""
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import functools
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import pickle
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import numpy as np
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def y_to_base_addr(y: int, page: int = 0) -> int:
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"""Maps y coordinate to base address on given screen page"""
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a = y // 64
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d = y - 64 * a
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b = d // 8
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c = d - 8 * b
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addr = 8192 * (page + 1) + 1024 * c + 128 * b + 40 * a
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return addr
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Y_TO_BASE_ADDR = [
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[y_to_base_addr(y, screen_page) for y in range(192)]
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for screen_page in (0, 1)
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]
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# Array mapping (page, offset) to x (byte) and y coords respectively
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# TODO: is np.dtype(int) faster for these?
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PAGE_OFFSET_TO_X = np.zeros((32, 256), dtype=np.uint8)
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PAGE_OFFSET_TO_Y = np.zeros((32, 256), dtype=np.uint8)
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# Inverse mappings
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X_Y_TO_PAGE = np.zeros((192, 40), dtype=np.uint8)
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X_Y_TO_OFFSET = np.zeros((192, 40), dtype=np.uint8)
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# Mask of which (page, offset) bytes represent screen holes
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SCREEN_HOLES = np.full((32, 256), True, dtype=np.bool)
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# Dict mapping memory address to (page, y, x_byte) tuple
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ADDR_TO_COORDS = {}
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def _populate_mappings():
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for y in range(192):
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for x in range(40):
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y_base = Y_TO_BASE_ADDR[0][y]
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page = y_base >> 8
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offset = y_base - (page << 8) + x
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PAGE_OFFSET_TO_Y[page - 32, offset] = y
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PAGE_OFFSET_TO_X[page - 32, offset] = x
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X_Y_TO_PAGE[y, x] = page - 32
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X_Y_TO_OFFSET[y, x] = offset
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# This (page, offset) is not a screen hole
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SCREEN_HOLES[page - 32, offset] = False
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for p in range(2):
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a = Y_TO_BASE_ADDR[p][y] + x
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ADDR_TO_COORDS[a] = (p, y, x)
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_populate_mappings()
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class FlatMemoryMap:
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"""Linear 8K representation of HGR screen memory."""
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def __init__(self, screen_page: int, data: np.array = None):
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if screen_page not in [1, 2]:
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raise ValueError("Screen page out of bounds: %d" % screen_page)
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self.screen_page = screen_page # type: int
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self._addr_start = 8192 * self.screen_page
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self._addr_end = self._addr_start + 8191
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self.data = None # type: np.array
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if data is not None:
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if data.shape != (8192,):
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raise ValueError("Unexpected shape: %r" % (data.shape,))
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self.data = data
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else:
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self.data = np.zeros((8192,), dtype=np.uint8)
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def to_memory_map(self):
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return MemoryMap(self.screen_page, self.data.reshape((32, 256)))
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def write(self, addr: int, val: int) -> None:
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"""Updates screen image to set 0xaddr = val (including screen holes)"""
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if addr < self._addr_start or addr > self._addr_end:
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raise ValueError("Address out of range: 0x%04x" % addr)
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self.data[addr - self._addr_start] = val
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class MemoryMap:
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"""Page/offset-structured representation of HGR screen memory."""
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def __init__(self, screen_page: int, page_offset: np.array = None):
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if screen_page not in [1, 2]:
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raise ValueError("Screen page out of bounds: %d" % screen_page)
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self.screen_page = screen_page # type: int
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self._page_start = 32 * screen_page
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self.page_offset = None # type: np.array
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if page_offset is not None:
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if page_offset.shape != (32, 256):
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raise ValueError("Unexpected shape: %r" % (page_offset.shape,))
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self.page_offset = page_offset
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else:
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self.page_offset = np.zeros((32, 256), dtype=np.uint8)
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def to_flat_memory_map(self) -> FlatMemoryMap:
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return FlatMemoryMap(self.screen_page, self.page_offset.reshape(8192))
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def write(self, page: int, offset: int, val: int) -> None:
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"""Updates screen image to set (page, offset)=val (inc. screen holes)"""
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self.page_offset[page - self._page_start][offset] = val
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class DHGRBitmap:
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BYTE_MASK32 = [
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# 3333333222222211111110000000 <- byte 0.3
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#
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# 33222222222211111111110000000000 <- bit pos in uint32
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# 10987654321098765432109876543210
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# 0000GGGGFFFFEEEEDDDDCCCCBBBBAAAA <- pixel A..G
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# 3210321032103210321032103210 <- bit pos in A..G pixel
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0b00000000000000000000000011111111, # byte 0 influences A,B
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0b00000000000000001111111111110000, # byte 1 influences B,C,D
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0b00000000111111111111000000000000, # byte 2 influences D,E,F
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0b00001111111100000000000000000000, # byte 3 influences F,G
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]
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# How much to right-shift bits after masking to bring into int8/int12 range
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BYTE_SHIFTS = [0, 4, 12, 20]
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# Load edit distance matrices for masked, shifted byte 0..3 values
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# TODO: should go somewhere else since we don't use it here at all
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with open("transcoder/edit_distance.pickle", "rb") as ed:
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edit_distances = pickle.load(ed)
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def __init__(self, main_memory: MemoryMap, aux_memory: MemoryMap):
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self.main_memory = main_memory
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self.aux_memory = aux_memory
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self.packed = np.empty(shape=(32, 128), dtype=np.uint32)
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self._pack()
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def _pack(self):
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"""Interleave and pack aux and main memory into 28-bit uint32 array"""
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# Palette bit is unused for DHGR so mask it out
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aux = (self.aux_memory.page_offset & 0x7f).astype(np.uint32)
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main = (self.main_memory.page_offset & 0x7f).astype(np.uint32)
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# Interleave aux and main memory columns and pack 7-bit masked values
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# into a 28-bit value. This sequentially encodes 7 4-bit DHGR pixels.
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# See make_data_tables.py for more discussion about this representation.
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self.packed = (
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aux[:, 0::2] +
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(main[:, 0::2] << 7) +
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(aux[:, 1::2] << 14) +
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(main[:, 1::2] << 21)
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)
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@staticmethod
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@functools.lru_cache(None)
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def interleaved_byte_offset(x_byte: int, is_aux: bool) -> int:
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"""Returns 0..3 offset in ByteTuple for a given x_byte and is_aux"""
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is_odd = x_byte % 2 == 1
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if is_aux:
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if is_odd:
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return 2
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return 0
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else: # main memory
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if is_odd:
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return 3
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else:
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return 1
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@staticmethod
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def masked_update(byte_offset: int, old_value, new_value: int):
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# Mask out 7-bit value where update will go
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masked_value = old_value & ~(0x7f << (7 * byte_offset))
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update = (new_value & 0x7f) << (7 * byte_offset)
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return masked_value ^ update
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def apply(self, page: int, offset: int, is_aux: bool, value: int):
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"""Update packed representation of changing main/aux memory."""
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byte_offset = self.interleaved_byte_offset(offset, is_aux)
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packed_offset = offset // 2
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self.packed[page, packed_offset] = self.masked_update(
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byte_offset, self.packed[page, packed_offset], value)
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def mask_and_shift_data(self, data, byte_offset):
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"""Masks and shifts data into the 8 or 12-bit range."""
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return (data & self.BYTE_MASK32[byte_offset]) >> (
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self.BYTE_SHIFTS[byte_offset])
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