\r
interface\r
\r
-uses blinklist,pgtypes;\r
+{-$define bfifo_assert}\r
\r
-const\r
- pagesize=1420;\r
+uses\r
+ {$ifdef bfifo_assert}\r
+ sysutils,\r
+ {$endif}\r
+ pgtypes;\r
+\r
+var\r
+ bfifo_minallocsize:integer=4096;\r
\r
type\r
tfifo=class(tobject)\r
private\r
- l:tlinklist; {add to}\r
- getl:tlinklist; {remove from}\r
- ofs:integer;\r
- getofs:integer;\r
+ allocsize:integer;\r
+ lastallocsize:integer; //last seen before we freed the buffer\r
+ lastalloccount:integer;\r
+ p:pointer;\r
+ head,tail:integer;\r
+ function getallocsizeforsize(i:integer):integer;\r
public\r
size:integer;\r
+\r
procedure add(data:pointer;len:integer);\r
function get(var resultptr:pointer;len:integer):integer;\r
procedure del(len:integer);\r
- constructor create;\r
destructor destroy; override;\r
end;\r
\r
-\r
implementation\r
\r
+function tfifo.getallocsizeforsize(i:integer):integer;\r
var\r
- testcount:integer;\r
-\r
-{\r
+ a:integer;\r
+begin\r
+ //get smallest power of two >= i and >= minallocsize\r
\r
-xx1..... add\r
-xxxxxxxx\r
-....2xxx delete\r
+ if (i <= bfifo_minallocsize) then begin\r
+ result := bfifo_minallocsize;\r
+ exit;\r
+ end;\r
\r
-1 ofs\r
-2 getofs\r
+ result := i - 1;\r
+ for a := 1 to 31 do result := result or (i shr a);\r
+ inc(result);\r
\r
-}\r
+end;\r
\r
procedure tfifo.add;\r
var\r
a:integer;\r
- p:tlinklist;\r
+ p2:pointer;\r
begin\r
if len <= 0 then exit;\r
- inc(size,len);\r
- while len > 0 do begin\r
- p := l;\r
- if ofs = pagesize then begin\r
- p := tplinklist.create;\r
- if getl = nil then getl := p;\r
- getmem(tplinklist(p).p,pagesize);\r
- inc(testcount);\r
- linklistadd(l,p);\r
- ofs := 0;\r
+\r
+ {$ifdef bfifo_assert}\r
+ if (size < 0) then raise exception.create('tfifo.add: size<0: '+inttostr(size));\r
+ if (allocsize < 0) then raise exception.create('tfifo.add: allocsize<0: '+inttostr(allocsize));\r
+ if assigned(p) and (size = 0) then raise exception.create('tfifo.add: p assigned and size=0');\r
+ if assigned(p) and (allocsize = 0) then raise exception.create('tfifo.add: p assigned and allocsize=0');\r
+ {$endif}\r
+\r
+ if not assigned(p) then begin\r
+ {$ifdef bfifo_assert}\r
+ if (size > 0) then raise exception.create('tfifo.add: p not assigned and size>0: '+inttostr(size));\r
+ if (allocsize > 0) then raise exception.create('tfifo.add: p not assigned and allocsize>0: '+inttostr(allocsize));\r
+ {$endif}\r
+\r
+ //no buffer is allocated, allocate big enough one now\r
+ allocsize := getallocsizeforsize(len);\r
+\r
+ //reuse the biggest size seen to avoid unnecessary growing of the buffer all the time, but sometimes shrink it\r
+ //so an unnecessary big buffer isn't around forever\r
+ inc(lastalloccount);\r
+ if (lastalloccount and 7 = 0) then lastallocsize := getallocsizeforsize(lastallocsize div 2);\r
+\r
+ if allocsize < lastallocsize then allocsize := lastallocsize;\r
+\r
+ getmem(p,allocsize);\r
+ head := 0;\r
+ tail := 0;\r
+ end else if (head + len > allocsize) then begin\r
+ //buffer is not big enough to add new data to the end\r
+\r
+ if (size + len <= allocsize) then begin\r
+ //it will fit if we move the data in the buffer to the start first\r
+ if (size > 0) then move(pointer(taddrint(p) + tail)^,p^,size);\r
+ //if (size > 0) then move(p[tail],p[0],size);\r
+ end else begin\r
+ //grow the buffer\r
+\r
+ allocsize := getallocsizeforsize(size + len);\r
+\r
+ getmem(p2,allocsize);\r
+ move(pointer(taddrint(p) + tail)^,p2^,size);\r
+ freemem(p);\r
+ p := p2;\r
end;\r
- a := pagesize - ofs;\r
- if len < a then a := len;\r
- move(data^,pointer(taddrint(tplinklist(p).p)+ofs)^,a);\r
- inc(taddrint(data),a);\r
- dec(len,a);\r
- inc(ofs,a);\r
+ head := size;\r
+ tail := 0;\r
end;\r
+\r
+ {$ifdef bfifo_assert}\r
+ if (head + len > allocsize) or (head < 0) then raise exception.create('tfifo.add: allocsize - head < len: '+inttostr(allocsize)+' '+inttostr(head)+' '+inttostr(len));\r
+ if (not assigned(p)) then raise exception.create('tfifo.add: p '+inttostr(size));\r
+ {$endif}\r
+\r
+ inc(size,len);\r
+\r
+ move(data^,pointer(taddrint(p) + head)^,len);\r
+ inc(head,len);\r
end;\r
\r
function tfifo.get;\r
-var\r
- p:tlinklist;\r
- a:integer;\r
begin\r
if len > size then len := size;\r
if len <= 0 then begin\r
resultptr := nil;\r
exit;\r
end;\r
- p := getl;\r
- resultptr := pointer(taddrint(tplinklist(p).p)+getofs);\r
- result := pagesize-getofs;\r
- if result > len then result := len;\r
+\r
+ //return a pointer into the buffer without copying\r
+ result := len;\r
+\r
+ resultptr := pointer(taddrint(p) + tail);\r
end;\r
\r
procedure tfifo.del;\r
-var\r
- a:integer;\r
- p,p2:tlinklist;\r
begin\r
if len <= 0 then exit;\r
- p := getl;\r
- if len > size then len := size;\r
- dec(size,len);\r
\r
- if len = 0 then exit;\r
-\r
- while len > 0 do begin\r
- a := pagesize-getofs;\r
- if a > len then a := len;\r
- inc(getofs,a);\r
- dec(len,a);\r
- if getofs = pagesize then begin\r
- p2 := p.prev;\r
- freemem(tplinklist(p).p);\r
- dec(testcount);\r
- linklistdel(l,p);\r
- p.destroy;\r
- p := p2;\r
- getl := p;\r
- getofs := 0;\r
- end;\r
- end;\r
+ {$ifdef bfifo_assert}\r
+ if (size < 0) then raise exception.create('tfifo.del: size negative: '+inttostr(size));\r
+ if (head - tail <> size) then raise exception.create('tfifo.del: size head tail: '+inttostr(size)+' '+inttostr(head)+' '+inttostr(tail));\r
+ if (head > allocsize) then raise exception.create('tfifo.del: head allocsize: '+inttostr(head)+' '+inttostr(allocsize));\r
+ {$endif}\r
\r
- if size = 0 then begin\r
- if assigned(l) then begin\r
- p := l;\r
- freemem(tplinklist(p).p);\r
- dec(testcount);\r
- linklistdel(l,p);\r
- p.destroy;\r
- getl := nil;\r
- end;\r
- ofs := pagesize;\r
- getofs := 0;\r
- end;\r
-end;\r
+ if (len > size) then len := size;\r
\r
-constructor tfifo.create;\r
-begin\r
- ofs := pagesize;\r
- inherited create;\r
+ dec(size,len);\r
+ inc(tail,len);\r
+\r
+ if (size <= 0) then begin\r
+ if (allocsize > lastallocsize) then lastallocsize := allocsize;\r
+ allocsize := 0;\r
+ head := 0;\r
+ tail := 0;\r
+ if assigned(p) then freemem(p);\r
+ p := nil;\r
+ end;\r
end;\r
\r
destructor tfifo.destroy;\r
begin\r
del(size);\r
+\r
+ {$ifdef bfifo_assert}\r
+ if assigned(p) then raise exception.create('tfifo.destroy: did not free '+inttostr(size)+' '+inttostr(allocsize));\r
+ {$endif}\r
+\r
inherited destroy;\r
end;\r
\r
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