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+ added function for computing the hash for the omf libraries' dictionary

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git-svn-id: trunk@30644 -
This commit is contained in:
nickysn 2015-04-18 10:48:49 +00:00
parent cebd3de630
commit 3ce29dcfb2
1 changed files with 54 additions and 0 deletions
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54
compiler/omfbase.pas
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@ -462,9 +462,19 @@ interface
property FrameDatum: Integer read FFrameDatum write FFrameDatum;
end;
TOmfLibHash = record
block_x: Integer;
block_d: Integer;
bucket_x: Integer;
bucket_d: Integer;
end;
function compute_omf_lib_hash(const name: string; blocks: Integer): TOmfLibHash;
implementation
uses
cutils,
verbose;
{ TOmfOrderedNameCollection }
@ -1396,5 +1406,49 @@ implementation
Result:=Offset;
end;
function compute_omf_lib_hash(const name: string; blocks: Integer): TOmfLibHash;
const
blank=$20; // ASCII blank
nbuckets=37;
var
block_x: Integer;
block_d: Integer;
bucket_x: Integer;
bucket_d: Integer;
len: Integer;
pbidx,peidx: Integer;
cback,cfront: Byte;
begin
len:=Length(name);
if len=0 then
internalerror(2015041801);
pbidx:=1;
peidx:=len+1;
{ left to right scan }
block_x:=len or blank;
bucket_d:=block_x;
{ right to left scan }
block_d:=0;
bucket_x:=0;
while true do
begin
{ blank -> convert to LC }
Dec(peidx);
cback:=Byte(name[peidx]) or blank;
bucket_x:=RorWord(bucket_x,2) xor cback;
block_d:=RolWord(block_d,2) xor cback;
Dec(len);
if len=0 then
break;
cfront:=Byte(name[pbidx]) or blank;
Inc(pbidx);
block_x:=RolWord(block_x,2) xor cfront;
bucket_d:=RorWord(bucket_d,2) xor cfront;
end;
Result.block_x:=block_x mod blocks;
Result.block_d:=max(block_d mod blocks,1);
Result.bucket_x:=bucket_x mod nbuckets;
Result.bucket_d:=max(bucket_d mod nbuckets,1);
end;
end.