[zvm commit] r206 - in trunk: tests zvm

[codesite...@google.com]

Author: sussman
Date: Sat Jun 28 13:41:41 2008
New Revision: 206

Modified:
trunk/tests/quetzal_tests.py
trunk/zvm/quetzal.py
trunk/zvm/zmemory.py

Log:
More work on quetzal.py.

Modified: trunk/tests/quetzal_tests.py
==============================================================================
--- trunk/tests/quetzal_tests.py (original)
+++ trunk/tests/quetzal_tests.py Sat Jun 28 13:41:41 2008
@@ -33,4 +33,5 @@
'checksum': 19942, \
'release number': 16, \
'serial number': '951024', \
+ 'program counter': 176149, \
'CMem': 437, 'Stks': 40, 'IFhd': 13})

Modified: trunk/zvm/quetzal.py
==============================================================================
--- trunk/zvm/quetzal.py (original)
+++ trunk/zvm/quetzal.py Sat Jun 28 13:41:41 2008
@@ -34,6 +34,9 @@
"General exception for Quetzal classes."
pass

+class QuetzalMalformedChunk(QuetzalError):
+ "Malformed chunk detected."
+
class QuetzalNoSuchSavefile(QuetzalError):
"Cannot locate save-game file."

@@ -76,17 +79,23 @@
raise QuetzalIllegalChunkOrder

bytes = [ord(x) for x in data]
+ if len(bytes) != 13:
+ raise QuetzalMalformedChunk
+
chunk_release = (ord(data[0]) << 8) + ord(data[1])
chunk_serial = data[2:8]
chunk_checksum = (ord(data[8]) << 8) + ord(data[9])
- ### TODO!!! see section 5.8. Wha? Huh? Read 3 bytes of Program Counter?
+ chunk_pc = (ord(data[10]) << 16) + (ord(data[11]) << 8) + ord(data[12])
+ self._zmachine._opdecoder.program_counter = chunk_pc

log(" Found release number %d" % chunk_release)
log(" Found serial number %d" % int(chunk_serial))
log(" Found checksum %d" % chunk_checksum)
+ log(" Initial program counter value is %d" % chunk_pc)
self._last_loaded_metadata["release number"] = chunk_release
self._last_loaded_metadata["serial number"] = chunk_serial
self._last_loaded_metadata["checksum"] = chunk_checksum
+ self._last_loaded_metadata["program counter"] = chunk_pc

# Verify the save-file params against the current z-story header
mem = self._zmachine._mem
@@ -96,12 +105,7 @@
if serial_bytes != mem[0x12:0x18]:
raise QuetzalMismatchedFile
mem_checksum = mem.read_word(0x1C)
- if mem_checksum == 0:
- ### Some old infocom games don't have checksums stored in header.
- ### TODO: add checksum routine to ZMemory (see 'verify' opcode)
- ### and call it to compute checksum manually.
- pass
- if mem_checksum != chunk_checksum:
+ if mem_checksum != 0 and (mem_checksum != chunk_checksum):
raise QuetzalMismatchedFile
log(" Quetzal file correctly verifies against original story.")

@@ -372,7 +376,14 @@
"""Return a chunk of type IFhd, containing metadata about the
zmachine and story being played."""

- ### TODO: write this
+ ### TODO: write this. payload must be *exactly* 13 bytes, even if
+ ### it means padding the program counter.
+
+ ### Some old infocom games don't have checksums stored in header.
+ ### If not, generate it from the *original* story file memory
+ ### image and put it into this chunk. See ZMemory.generate_checksum().
+ pass
+
return "0"

Modified: trunk/zvm/zmemory.py
==============================================================================
--- trunk/zvm/zmemory.py (original)
+++ trunk/zvm/zmemory.py Sat Jun 28 13:41:41 2008
@@ -252,3 +252,16 @@
bf = bitfield.BitField(value)
self._memory[actual_address] = bf[8:15]
self._memory[actual_address + 1] = bf[0:7]
+
+ # The 'verify' opcode and the QueztalWriter class both need to have
+ # a checksum of memory generated.
+
+ def generate_checksum(self):
+ """Return a checksum value which represents all the bytes of
+ memory added from $0040 upwards, modulo $10000."""
+ count = 0x40
+ total = 0
+ while count < self._total_size:
+ total += self._memory[count]
+ count += 1
+ return (total % 0x10000)