Find sequence in binary fiel and advance from there

[H. S. Teoh]

On Tue, May 07, 2019 at 08:26:16AM +0000, alex1974 via Digitalmars-d-learn wrote:
> I want to read a binary file and validate that it contains the
> sequence [73,68,51] (ID3). And than start to read from this position
> onward.
> 
> I could read in the whole file as an ubyte array but I would prefer a
> range-based solution. Has anyone done this and could point me in the
> right direction?
[...]

For I/O, generally a block-based approach would be better than a range
over individual bytes.  It would be extremely slow if you incurred an OS
syscall roundtrip per byte accessed.  You can, however, still expose a
range of ubyte on top of a buffered underlying access pattern, though,
by using .joiner.

However, for maximum ease, you could just use std.mmfile and mmap the
file into your process address space, and just slice over the file
contents as a ubyte[]. Maximum ease and also optimal performance (OS
handles the paging for you).


T

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