On Wednesday, 11 January 2017 at 17:32:35 UTC, Era Scarecrow
wrote:
Still I think I'll impliment my own version and then if it's
faster I'll submit it.
Decided I'd give my hand at writing a 'ScaledInt' which is
intended to basically allow any larger unsigned type. Coming
across some assembly confusion.
Using mixin with assembly here's the 'result' of the mixin (as a
final result)
alias UCent = ScaledInt!(uint, 4);
struct ScaledInt(I, int Size)
if (isUnsigned!(I) && Size > 1) {
I[Size] val;
ScaledInt opBinary(string op)(const ScaledInt rhs) const
if (op == "+") {
ScaledInt t;
asm pure nothrow { //mixin generated from another
function, for simplicity
mov EBX, this;
clc;
mov EAX, rhs[EBP+0];
adc EAX, val[EBX+0];
mov t[EBP+0], EAX;
mov EAX, rhs[EBP+4];
adc EAX, val[EBX+4];
mov t[EBP+4], EAX;
mov EAX, rhs[EBP+8];
adc EAX, val[EBX+8];
mov t[EBP+8], EAX;
mov EAX, rhs[EBP+12];
adc EAX, val[EBX+12];
mov t[EBP+12], EAX;
}
return t;
}
}
Raw disassembly for my asm code shows this:
mov EBX,-4[EBP]
clc
mov EAX,0Ch[EBP]
adc EAX,[EBX]
mov -014h[EBP],EAX
mov EAX,010h[EBP]
adc EAX,4[EBX]
mov -010h[EBP],EAX
mov EAX,014h[EBP]
adc EAX,8[EBX]
mov -0Ch[EBP],EAX
mov EAX,018h[EBP]
adc EAX,0Ch[EBX]
mov -8[EBP],EAX
From what I'm seeing, it should be 8, 0ch, 10h, then 14h, all
positive. I'm really scratching my head why I'm having this
issue... Doing an add of t[0] = val[0] + rhs[0]; i get this
disassembly:
mov EDX,-4[EBP] //mov EDX, this;
mov EBX,[EDX] //val[0]
add EBX,0Ch[EBP]//+ rhs.val[0]
mov ECX,8[EBP] //mov ECX, ???[???]
mov [ECX],EBX //t.val[0] =
If i do "mov ECX,t[EBP]", i get "mov ECX,-014h[EBP]". If i try to
reference the exact variable val within t, it complains it
doesn't know it at compiler-time (although it's a fixed location).
What am i missing here?
