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https://github.com/KrisKennaway/ii-vision.git
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55 lines
1.5 KiB
Python
55 lines
1.5 KiB
Python
from typing import Tuple
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import screen
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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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class MemoryMap:
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"""Memory map representing screen memory."""
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# TODO: support DHGR
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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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ADDR_TO_COORDS = {}
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for p in range(2):
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for y in range(192):
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for x in range(40):
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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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def __init__(self, screen_page: int, bytemap: screen.Bytemap):
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self.screen_page = screen_page # type: int
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self.bytemap = bytemap
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def to_page_offset(self, x_byte: int, y: int) -> Tuple[int, int]:
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y_base = self.Y_TO_BASE_ADDR[self.screen_page][y]
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page = y_base >> 8
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# print("y=%d -> page=%02x" % (y, page))
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offset = y_base - (page << 8) + x_byte
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return page, offset
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def write(self, addr: int, val: int) -> None:
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"""Updates screen image to set 0xaddr ^= val"""
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try:
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_, y, x = self.ADDR_TO_COORDS[addr]
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except KeyError:
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# TODO: filter out screen holes
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# print("Attempt to write to invalid offset %04x" % addr)
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return
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self.bytemap.bytemap[y][x] = val
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