我在我的并行语言中使用了帕斯卡。(我不喜欢它,但是强制。)所以
合并排序与 fork & join 并行不起作用,有人可以告诉我为什么吗?
这是我的代码:
program parrallelmergesort;
architecture shared(100);
const
n=100;(*big array*)
size=10;
var
t,globalCounter:integer;
unsorted:array[1..n] of integer;
procedure CallMerge(var lower,mid,high:integer);
var
i,j,k,count:integer;
S:array[1..n] of integer;
BEGIN
i:=lower;
j:=mid+1;
k:=lower;
count:=high-lower+1;
while (i<=mid) and (j<=high) do
begin
if unsorted[i]<unsorted[j] then
begin
S[k] :=unsorted[i];
i :=i+1;
end
else
begin
S[k] :=unsorted[j];
j :=j+1;
end;
k:=k+1;
end;
if i>mid then
begin
while j<=high do
begin
S[k] :=unsorted[j];
j :=j+1;
k :=k+1;
end;
end
else if j>high then
begin
while i<=mid do
begin
S[k] :=unsorted[i];
i :=i+1;
k :=k+1;
end;
end;
for t:=lower to high do
unsorted[t] :=S[t];
end;
procedure CallMergeSort(bottom,up:integer);
var middle,nextOfMiddle:integer;
begin
if up>bottom then
begin
middle := (up+bottom) div 2;
nextofMiddle :=middle+1;
fork CallMergeSort(bottom,middle);
fork CallMergeSort(nextOfMiddle,up);
join;join;
CallMerge(bottom,middle,up);
end;
end;
begin
unsorted[1] :=4; unsorted[2] :=3; unsorted[3] :=10; unsorted[4] :=5; unsorted[5] :=0;
unsorted[6] :=1; unsorted[7] :=8; unsorted[8] :=6; unsorted[9] :=11; unsorted[10] :=12;
CallMergeSort(1,size);
for globalCounter:=1 to size do
writeln(unsorted[globalCounter]);
readln;
end.
我应该什么时候使用 fork ?在 CallMergeSort(递归)之前?
最后几行是帕斯卡的主要功能。