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GRiSP Erlang Runtime Library

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grisp src grisp_bitmap.erl
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src/grisp_bitmap.erl 

-module(grisp_bitmap).



% API

-export([set_bits/3]).

-export([get_bits/3]).

-export([set_bytes/3]).

-export([get_bytes/3]).



%--- API -----------------------------------------------------------------------



set_bits(Bin, Start, Value) when bit_size(Bin) >= Start + bit_size(Value) ->

    Len = bit_size(Value),

    <<Prefix:Start/bitstring, _:Len/bitstring, Postfix/bitstring>> = Bin,

    <<Prefix/bitstring, Value/bitstring, Postfix/bitstring>>.



get_bits(Bin, Start, Len) ->

    <<_:Start/bitstring, Bytes:Len/bitstring, _/bitstring>> = Bin,

    Bytes.



set_bytes(Bin, Start, Value) when is_binary(Value) ->

    set_bits(Bin, Start * 8, Value).



get_bytes(Bin, Start, Len) ->

    get_bits(Bin, Start * 8, Len * 8).