Inline assembly issue

[Aik_T]

Assuming targeting X86_64 and using the systemV ABI then the parameters are passed in XMM0 and XMM1. You can then just do an SSE division and leave (result is in XMM0). If you really do want to use the FPU then you must copy the parameters to locals. And the rest is just like in the previous answer.
On windows that might be different.

Thank you! I found such a variant in Daniel Kusswurm's book, but I was wondering how it works in a more classic version. Anyway, that's helpful, thanks

[Aik_T]

Thanks everyone!
The only thing is that you can't pass numbers directly to the function:

Code: Pascal  [Select][+][-]

1. Division(10, 2);

You need to pass variables

Code: Pascal  [Select][+][-]

1. Division(A, B);

Thanks everyone for helping

[srvaldez]

Aik_T
the following works on Windows x86 and x64

Code: Pascal  [Select][+][-]

1.     program Project1;
2.     {$asmmode intel}
3.     {$MODE OBJFPC}{$H+}
4.  
5.     function Division( a, b:Single): Single; assembler;
6.     {$ifdef CPU64}
7.     var
8.         x, y: Single;
9.     {$endif}
10.     asm
11.         {$ifdef CPU32}
12.             fld   dword ptr [a]
13.             Fdiv  dword ptr [b]
14.             Fstp  dword ptr [Result]
15.         {$else}
16.             movss x, xmm0
17.             movss y, xmm1
18.             fld   dword ptr [x]
19.             fdiv  dword ptr [y]
20.             Fstp  dword ptr [Result]
21.         {$endif}
22.     end;
23.  
24.     var
25.         x, y:Single;
26.     begin
27.         x:=10;
28.         y:=5;
29.         writeln(Division(x, y));
30.         writeln(Division(25, 5));
31.         write('Press Return ');ReadLn;
32.     end.
33.  

[srvaldez]

integer cube root code borrowed from Mparith

Code: Pascal  [Select][+][-]

1.     program Project1;
2.     {$asmmode intel}
3.     {$MODE OBJFPC}{$H+}
4.  
5. // code borrowed from Mparith https://forum.lazarus.freepascal.org/index.php/topic,68447.msg528998.html#msg528998
6. // file mp_base.bas, lines 1754 .. 1808
7. // conditional compilation added by srvaldez
8.  
9.     {For VPC, D2/D3; cardinal is only 31 bit}
10.     {---------------------------------------------------------------------------}
11.     function icbrt32(a: longint): longint;
12.     {-Return the integer cube root sign(a)*floor(|a|^(1/3))}
13.     var
14.     x: longint;
15.     begin
16.     {Ref: http://www.hackersdelight.org/hdcodetxt/icbrt.c.txt}
17.  
18.     {Note: There will be RTEs for large a if Range!? checking (not obverflow)}
19.     {is done, e.g. in debug mode. Here a 32-bit BASM port of the Pascal code:}
20.     x := abs(a);
21.     if x>7 then begin
22.       {y=ebx, y2=esi, s=cx, b=edi, x=eax}
23.       asm
24.         {$if defined(Win32)}
25.             push edi
26.             push esi
27.             push ebx
28.         {$elseif defined(Win64)}
29.             push rdi
30.             push rsi
31.             push rbx
32.         {$endif}
33.             mov  eax,[x]
34.             xor  ebx,ebx       {y  := 0}
35.             xor  esi,esi       {y2 := 0}
36.             mov  cx,30         {s  := 30}
37.       @@1:  shl  esi,2         {y2 := y2 shl 2}
38.             add  ebx,ebx
39.             mov  edx,ebx
40.             add  edx,esi       {edx:= y2+y}
41.             mov  edi,edx
42.             add  edi,edi
43.             add  edi,edx       {edi:= 3*(y2+y)}
44.             inc  edi
45.             shl  edi,cl        {b  := 3*(y2 + y) + 1) shl s}
46.             cmp  edi,eax
47.             ja   @@2
48.             sub  eax,edi       {x  := x - b}
49.             add  esi,ebx
50.             inc  ebx           {y  := y + 1}
51.             add  esi,ebx       {y2 := y2 + y + (y+1)}
52.       @@2:  sub  cx,3
53.             jnl  @@1
54.             mov  [x],ebx
55.         {$if defined(Win32)}
56.             pop  ebx
57.             pop  esi
58.             pop  edi
59.         {$elseif defined(Win64)}
60.             pop  rbx
61.             pop  rsi
62.             pop  rdi
63.         {$endif}
64.       end;
65.       if a<0 then icbrt32 := -x
66.       else icbrt32 := x;
67.     end
68.     else begin
69.       { -7 <= a <= 7, ie icbrt = -1,0,1}
70.       if a>0 then icbrt32 := 1
71.       else if a<0 then icbrt32 := -1
72.       else icbrt32 := 0;
73.     end;
74.     end;
75.  
76. // test the integer cube root function
77.     var
78.         n, r:longint;
79.     begin
80.         n:=27;
81.         r:=icbrt32(n);
82.         writeln('the cube root of ', n, ' = ', r);
83.         writeln('the cube root of 8 = ', icbrt32(8));
84.     end.
85.  

[Aik_T]

Aik_T
the following works on Windows x86 and x64

Code: Pascal  [Select][+][-]

1.     program Project1;
2.     {$asmmode intel}
3.     {$MODE OBJFPC}{$H+}
4.  
5.     function Division( a, b:Single): Single; assembler;
6.     {$ifdef CPU64}
7.     var
8.         x, y: Single;
9.     {$endif}
10.     asm
11.         {$ifdef CPU32}
12.             fld   dword ptr [a]
13.             Fdiv  dword ptr [b]
14.             Fstp  dword ptr [Result]
15.         {$else}
16.             movss x, xmm0
17.             movss y, xmm1
18.             fld   dword ptr [x]
19.             fdiv  dword ptr [y]
20.             Fstp  dword ptr [Result]
21.         {$endif}
22.     end;
23.  
24.     var
25.         x, y:Single;
26.     begin
27.         x:=10;
28.         y:=5;
29.         writeln(Division(x, y));
30.         writeln(Division(25, 5));
31.         write('Press Return ');ReadLn;
32.     end.
33.  

It works! Thanks!