These parts of the code essentially check whether
stepping back by rep0 goes negative or not.
LZMA SDK from lzma1604.7z has the following in the corresponding places:
... = dic[dicPos - rep0 + (dicPos < rep0 ? dicBufSize : 0)]
Clearly, not loop here.
Technically, "while" here works: if condition is false (because pos
underflowed), it iterates once, adds header.dict_size (a.k.a. dicBufSize),
this makes pos positive but smaller than header.dict_size, and loop exits.
Now we'll just check for negative result of subtraction, which is less code:
function old new delta
unpack_lzma_stream 2659 2641 -18
(I hope 2 Gbyte+ dictionaries won't be in use soon).
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
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