Apple-2-Tools/atrcopy
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Relaxed constraints for interleaving segments

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* use size of smallest segment as size to interleave
* adjust downward if interleave factor not an integer multiple of size
This commit is contained in:
Rob McMullen 2017-05-10 10:38:20 -07:00
parent eee02b14cb
commit bdaa44755a
2 changed files with 74 additions and 23 deletions
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29
atrcopy/segments.py
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@ -1134,21 +1134,28 @@ class RawTrackSectorSegment(RawSectorsSegment):
def interleave_indexes(segments, num_bytes): def interleave_indexes(segments, num_bytes):
num_segments = len(segments) num_segments = len(segments)
# interleave size will be the smallest segment
size = len(segments[0]) size = len(segments[0])
for s in segments[1:]: for s in segments[1:]:
if size != len(s): if len(s) < size:
raise ValueError("All segments to interleave must be the same size") size = len(s)
# adjust if byte spacing is not an even divisor
_, rem = divmod(size, num_bytes) _, rem = divmod(size, num_bytes)
if rem != 0: print("size: %d, rem=%d" % (size, rem))
raise ValueError("Segment size must be a multiple of the byte interleave") size -= rem
print("size: %d, rem=%d" % (size, rem))
interleave = np.empty(size * num_segments, dtype=np.uint32) interleave = np.empty(size * num_segments, dtype=np.uint32)
factor = num_bytes * num_segments if size > 0:
start = 0 factor = num_bytes * num_segments
for s in segments: start = 0
order = s.rawdata.get_indexes_from_base() for s in segments:
for i in range(num_bytes): order = s.rawdata.get_indexes_from_base()
interleave[start::factor] = order[i::num_bytes] for i in range(num_bytes):
start += 1 interleave[start::factor] = order[i:size:num_bytes]
start += 1
return interleave return interleave

68
test/test_segment.py
View File

@ -169,21 +169,65 @@ class TestIndexed(object):
a[7::8] = s2[3::4] a[7::8] = s2[3::4]
assert np.array_equal(s[:], a) assert np.array_equal(s[:], a)
with pytest.raises(ValueError) as e: def test_interleave_not_multiple(self):
s = interleave_segments([s1, s2], 3) base = self.segment
r1 = base.rawdata[512:1024] # 512 byte segment
r1 = base.rawdata[512:1025] # 513 byte segment
s1 = DefaultSegment(r1, 512) s1 = DefaultSegment(r1, 512)
r2 = base.rawdata[1024:1537] # 513 byte segment r2 = base.rawdata[1024:1536] # 512 byte segment
s2 = DefaultSegment(r2, 1024) s2 = DefaultSegment(r2, 1024)
indexes1 = r1.get_indexes_from_base()
verify1 = np.arange(512, 1024, dtype=np.uint32)
assert np.array_equal(indexes1, verify1)
indexes2 = r2.get_indexes_from_base()
verify2 = np.arange(1024, 1536, dtype=np.uint32)
assert np.array_equal(indexes2, verify2)
s = interleave_segments([s1, s2], 3) s = interleave_segments([s1, s2], 3)
a = np.empty(len(s1) + len(s2), dtype=np.uint8)
a[0::6] = s1[0::3] # when interleave size isn't a multiple of the length, the final array
a[1::6] = s1[1::3] # will reduce the size of the input array to force it to be a multiple.
a[2::6] = s1[2::3] size = (len(s1) // 3) * 3
a[3::6] = s2[0::3] assert len(s) == size * 2
a[4::6] = s2[1::3] a = np.empty(len(s), dtype=np.uint8)
a[5::6] = s2[2::3] a[0::6] = s1[0:size:3]
a[1::6] = s1[1:size:3]
a[2::6] = s1[2:size:3]
a[3::6] = s2[0:size:3]
a[4::6] = s2[1:size:3]
a[5::6] = s2[2:size:3]
assert np.array_equal(s[:], a)
def test_interleave_different_sizes(self):
base = self.segment
r1 = base.rawdata[512:768] # 256 byte segment
s1 = DefaultSegment(r1, 512)
r2 = base.rawdata[1024:1536] # 512 byte segment
s2 = DefaultSegment(r2, 1024)
indexes1 = r1.get_indexes_from_base()
verify1 = np.arange(512, 768, dtype=np.uint32)
assert np.array_equal(indexes1, verify1)
indexes2 = r2.get_indexes_from_base()
verify2 = np.arange(1024, 1536, dtype=np.uint32)
assert np.array_equal(indexes2, verify2)
s = interleave_segments([s1, s2], 3)
# when interleave size isn't a multiple of the length, the final array
# will reduce the size of the input array to force it to be a multiple.
size = (min(len(s1), len(s2)) // 3) * 3
assert size == (256 // 3) * 3
assert len(s) == size * 2
a = np.empty(len(s), dtype=np.uint8)
a[0::6] = s1[0:size:3]
a[1::6] = s1[1:size:3]
a[2::6] = s1[2:size:3]
a[3::6] = s2[0:size:3]
a[4::6] = s2[1:size:3]
a[5::6] = s2[2:size:3]
assert np.array_equal(s[:], a) assert np.array_equal(s[:], a)
def test_copy(self): def test_copy(self):