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Let functions create/parse their own res header.

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This commit is contained in:
Elliot Nunn 2018-12-13 12:46:49 +08:00
parent 7f14013fa3
commit eacebc8320
1 changed files with 24 additions and 11 deletions
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35
GreggBits.py
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@ -85,16 +85,19 @@ def DecodeMaskedWords(src, dst, pos, n, tab, mask):
return pos
def GreggDecompress(src, dst, unpackSize, tabSize, comprFlags):
def GreggDecompress(src, dst, unpackSize, pos=0):
'''Decompress resource data from src to dst.
Parameters:
src source buffer containing compressed data
dst destination buffer, must be bytearray to work properly
unpackSize size in bytes of the unpacked resource data
tabSize size of the embedded lookup table
comprFlags compression flags from the extended resource header
pos offset to my Gregg-specific buffer in src
'''
_dcmp, _slop, tabSize, comprFlags = struct.unpack_from(">HHBB", src, pos)
pos += 6
hasDynamicTab = comprFlags & 1
isBitmapped = comprFlags & 2
print("tabSize: %d" % tabSize)
@ -103,8 +106,8 @@ def GreggDecompress(src, dst, unpackSize, tabSize, comprFlags):
if hasDynamicTab:
nEntries = tabSize + 1
pos = nEntries * 2
dynamicLUT = struct.unpack(">" + str(nEntries) + "H", src[:pos])
dynamicLUT = struct.unpack_from(">" + str(nEntries) + "H", src, pos)
pos += nEntries * 2
# dump dynamic LUT
if 0:
for idx, elem in enumerate(dynamicLUT):
@ -114,8 +117,6 @@ def GreggDecompress(src, dst, unpackSize, tabSize, comprFlags):
print(", ", end="")
print("0x%04X" % elem, end="")
print("")
else:
pos = 0
LUT = dynamicLUT if hasDynamicTab else GreggDefLUT
nWords = unpackSize >> 1
@ -149,10 +150,14 @@ def GreggDecompress(src, dst, unpackSize, tabSize, comprFlags):
#print("Last input position: %d" % pos)
def GreggCompress(src, dst, unpackSize, customTab=False, isBitmapped=False):
if customTab:
def GreggCompress(src, dst, customTab='auto', isBitmapped='auto'):
# future addition
customTab = True # so the big code path gets tested!
isBitmapped = True # required for now
if customTab: # calculate, and if necessary, resolve 'auto'
# convert input bytes into an array of words
nWords = unpackSize >> 1
nWords = len(src) >> 1
inWords = struct.unpack(">" + str(nWords) + "H", src[:nWords*2])
# count occurence of each word
@ -193,6 +198,14 @@ def GreggCompress(src, dst, unpackSize, customTab=False, isBitmapped=False):
print("0x%04X" % elem, end="")
print("")
# here, decide whether 'auto' customTab should be on or off!
# write out the header
isBitmapped = True # will need to resolve this later
flags = customTab * 1 + isBitmapped * 2
dst.extend(struct.pack(">HHBB", 2, 0, len(embeddedTab)-1, flags))
if customTab:
# write the constructed table into output
for word in embeddedTab:
dst.extend(word.to_bytes(2, 'big'))
@ -207,7 +220,7 @@ def GreggCompress(src, dst, unpackSize, customTab=False, isBitmapped=False):
if nWords & 7:
pos = EncodeMaskedWords(inWords, dst, pos, nWords & 7, embeddedTab)
if unpackSize & 1: # copy over last byte in the case of odd length
if len(src) & 1: # copy over last byte in the case of odd length
dst.append(src[-1])
else:
print("Non-bitmapped compression not yet implemented")