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Simba/Units/Misc/bzip2comn.pp

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unit bzip2comn;
interface
const
max_groups = 6;
max_alpha_size = 258;
max_code_len = 23;
group_size = 50;
iter_count = 4;
max_selectors = 2+(900000 div group_size);
mtfa_size = 4096;
mtfl_size = 16;
type
TCardinal_array = array [0..899999] of Cardinal;
PCardinal_array = ^TCardinal_array;
PCardinal = ^Cardinal;
Thuffarray = array[0..max_alpha_size] of Cardinal;
Phuffarray = ^Thuffarray;
{A bzip2 stream starts with this:}
const bzip2_stream_magic='BZh';
{Error codes for stream errorinfo.}
const
bzip2_bad_header_magic = 1;
bzip2_bad_block_magic = 2;
bzip2_endoffile = 3;
bzip2_data_error = 4;
procedure hb_create_decode_tables(var limit,base,perm:array of cardinal;
var length:array of byte;
minlen,maxlen:byte;alphasize:cardinal);
implementation
procedure hb_create_decode_tables(var limit,base,perm:array of cardinal;
var length:array of byte;
minlen,maxlen:byte;alphasize:cardinal);
var pp,i,j,vec:cardinal;
begin
pp:=0;
for i:=minlen to maxlen do
for j:=0 to alphasize-1 do
if length[j]=i then
begin
perm[pp]:=j;
inc(pp);
end;
for i:=0 to max_code_len-1 do
begin
base[i]:=0;
limit[i]:=0;
end;
for i:=0 to alphasize-1 do
inc(base[length[i]+1]);
for i:=1 to max_code_len-1 do
inc(base[i],base[i-1]);
vec:=0;
for i:=minlen to maxlen do
begin
inc(vec,base[i+1]-base[i]);
limit[i]:=vec-1;
vec:=vec shl 1;
end;
for i:=minlen+1 to maxlen do
base[i]:=((limit[i-1]+1) shl 1)-base[i];
end;
end.