infogulch wrote:
I think you forgot the first part btw:
I had forgotten VarSetCapacity ignores RequestedCapacity when filling the variable.
VarSetCapacity(buf, 128), VarSetCapacity(buf, 0) helps because it prevents buf from being allocated persistent memory, instead forcing the allocations to be the requested size. However, it only has an effect on the first call, then it becomes unnecessary overhead. (Edit: It should also be noted that this is undocumented behaviour and as such should not be relied upon.) Here is an alternative approach:
Code:
FillChar(char=" ", cnt=100) {
if A_IsUnicode
VarSetCapacity(buf, cnt*2, 1), NumPut(0, buf, cnt*2, "short")
, DllCall("msvcrt\_wcsset", "str", buf, "int", Asc(char), "Cdecl")
else
VarSetCapacity(buf, cnt, 1), NumPut(0, buf, cnt, "char")
, DllCall("msvcrt\_strset", "str", buf, "int", Asc(char), "Cdecl")
return buf
}
This explicitly null-terminates the variable at the correct position. It appears to add about
9% to the benchmark time (with default parameters), whereas the redundant VarSetCapacity method adds about
60%.
I also tried a variant using:
Code:
VarSetCapacity(buf, cnt*2, 1) != cnt*2 ? NumPut(0, buf, cnt*2, "short") : 0
...but it turns out that the code to avoid the unnecessary NumPut takes about as long as the NumPut itself.
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