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Simplify, bit extraction from Z values

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This commit is contained in:
Pierre Chambart 2018-05-09 17:34:16 +02:00 committed by Benjamin Canou
parent deffa28aa4
commit e16cf6d28b
1 changed files with 2 additions and 11 deletions
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13
src/lib_data_encoding/binary.ml
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@ -196,17 +196,8 @@ module Writer = struct
MBytes.set_int8 res ofs 0x00 ; MBytes.set_int8 res ofs 0x00 ;
ofs + 1 ofs + 1
end else end else
let raw = Z.to_bits v in let v = Z.abs v in
let get_chunk pos len (* < 8 *) = let get_chunk pos len = Z.to_int (Z.extract v pos len) in
let byte = pos / 8 in
let bit = pos mod 8 in
if bit + len <= 8 then
let mask = 0xFF lsr (8 - len) in
(Char.code (String.get raw byte) lsr bit) land mask
else
let mask = 0xFF lsr (16 - len - bit) in
(Char.code (String.get raw byte) lsr bit)
lor ((Char.code (String.get raw (byte + 1))) land mask) lsl (8 - bit) in
let length = (bits + 1 + 6) / 7 in let length = (bits + 1 + 6) / 7 in
MBytes.set_int8 res ofs MBytes.set_int8 res ofs
((if sign then 0x40 else 0x00) ((if sign then 0x40 else 0x00)