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c9c609be1d
This is a first step toward separating the CPU core and UI. The UI program
starts the CPU core as a subprocess and communicates through its standard input
and output. The protocol is deliberately simple at this point. Each bus request
from the core is exactly eight bytes:
+-------------------------+
| cpu cycle counter high |
+-------------------------+
| cpu cycle counter |
+-------------------------+
| cpu cycle counter |
+-------------------------+
| cpu cycle counter low |
+-------------------------+
| 0x00=read / 0x01=write |
+-------------------------+
| address high |
+-------------------------+
| address low |
+-------------------------+
| value (unused for read) |
+-------------------------+
A single-byte response from the UI is required for a read request, and a
response must not be sent for a write request.
The above protocol is expected to change. For example:
- the UI should tell the CPU core which address ranges are of interest
- needs ability to send memory images to the core (both ROM and RAM)
The stream communications is currently buggy because it expects that all eight
bytes will be read when requested (that is, partial reads are not handled). In
practice, this seems to work okay for the moment.
To improve portability, it may be better to communicate over TCP sockets
instead of stdin/stdout.
92 lines
1.9 KiB
Python
92 lines
1.9 KiB
Python
# ApplePy - an Apple ][ emulator in Python
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# James Tauber / http://jtauber.com/
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# originally written 2001, updated 2011
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import curses
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import struct
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import subprocess
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import sys
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kbd = 0
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def write_screen(win, address, value):
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base = address - 0x400
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hi, lo = divmod(base, 0x80)
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row_group, column = divmod(lo, 0x28)
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row = hi + 8 * row_group
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# skip if writing to row group 3
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if row_group == 3:
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return
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c = chr(0x20 + ((value + 0x20) % 0x40))
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if value < 0x40:
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attr = curses.A_DIM
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elif value < 0x80:
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attr = curses.A_REVERSE
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elif value < 0xA0:
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attr = curses.A_UNDERLINE
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else:
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attr = curses.A_DIM
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try:
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win.addch(row, column, c, attr)
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except curses.error:
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pass
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def read(addr, val):
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global kbd
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if addr == 0xC000:
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return kbd
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elif addr == 0xC010:
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kbd = kbd & 0x7F
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return 0x00
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def write(win, addr, val):
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if 0x400 <= addr <= 0x800:
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write_screen(win, addr, val)
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def run(win):
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global kbd
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p = subprocess.Popen(
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args=[sys.executable, "cpu6502.py"],
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stdin=subprocess.PIPE,
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stdout=subprocess.PIPE,
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)
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win.clear()
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curses.noecho()
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win.nodelay(True)
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while True:
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op = p.stdout.read(8)
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cycle, rw, addr, val = struct.unpack("<IBHB", op)
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if rw == 0:
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p.stdin.write(chr(read(addr, val)))
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p.stdin.flush()
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elif rw == 1:
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write(win, addr, val)
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else:
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break
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try:
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key = ord(win.getkey())
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if key == 0xA:
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key = 0xD
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elif key == 0x7F:
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key = 0x8
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# win.addstr(15, 50, hex(key))
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kbd = 0x80 | key
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except curses.error:
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pass
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except TypeError:
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pass
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if __name__ == "__main__":
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curses.wrapper(run)
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