bitRAKE's SWITCH MACRO

[jj2007]

Code Select Expand

include \masm32\MasmBasic\MasmBasic.inc
  Init
  mov ecx, 3
  Switch_ ecx
  Case_ 0
PrintLine "0"
  Case_ 3
PrintLine "3"
  Default_
PrintLine "default"
  Endsw_
EndOfCode

Code Select Expand

0088107C             ³.  B9 03000000        mov ecx, 3
00881081             ³.  3B0D D0108800      cmp ecx, [8810D0]
00881087             ³.  8B15 CC108800      mov edx, [MbSw1L]
0088108D             ³. 7F 2B              jg short MbSw1D
0088108F             ³.  03D1               add edx, ecx
00881091             ³. 7C 27              jl short MbSw1D
00881093             À.  FF2495 D4108800    jmp near [edx*4+8810D4]
MbSw10               Ú>  68 50908800        push offset ra_lbl2
0088109F             ³.  6A 01              push 1
008810A1             ³.  6A 02              push 2
008810A3             ³.  E8 BE130000        call MbPrint
008810A8             À. EB 3A              jmp short MbSw1
MbSw11               Ú>  68 54908800        push offset ra_lbl3
008810AF             ³.  6A 01              push 1
008810B1             ³.  6A 02              push 2
008810B3             ³.  E8 AE130000        call MbPrint
008810B8             À. EB 2A              jmp short MbSw1
MbSw1D               Ú>  68 58908800        push offset ra_lbl4        ; ASCII "default"
008810BF             ³.  6A 01              push 1
008810C1             ³.  6A 02              push 2
008810C3             ³.  E8 9E130000        call MbPrint
008810C8             ³. EB 1A              jmp short MbSw1
008810CA             ³   8BFF               mov edi, edi
MbSw1L               ³.  00000000           dd 00000000
008810D0             ³.  03000000           dd 00000003
008810D4             ³.  9A108800           dd MbSw10
008810D8             ³.  BA108800           dd MbSw1D
008810DC             ³.  BA108800           dd MbSw1D
008810E0             ³.  AA108800           dd MbSw11
MbSw1                ³>  6A 00              push 0

[habran]

OK, jj2007, I will test it and report to you ;)

[habran]

Are you kidding me :icon_eek:
What I was expecting is that you routine will not need to test for each occurrence and jump, but do something like this:
for 64 bit:
lea rax, @Jumptable
jmp [rax+rcx*8]

or for 32 bit:
jmp  @Jumptable[ecx*4]

not :
           cmp ecx,3
           jg @L1
           jmp  Case2
@L1:   cmp ecx,4
           jg @L2
           jmp  Case2
@L2:    cmp ecx,5
            jg @L3
           ---------

[jj2007]

jmp  @Jumptable[ecx*4]

see disassembly:
jmp near [edx*4+8810D4]

P.S.: In case you meant the two jumps, attached a special high performance version for use with plain Masm32. It saves 4 bytes (i.e. the two jumps), and should be significantly faster, too. All you have to do is to specify "unsafe" as the second argument.

Code Select Expand

include \masm32\include\masm32rt.inc
include SwitchUnsafe.mac
.code
start:
  m2m ecx, 1
  Switch_ ecx, unsafe
  Case_ 0
print "0"
  Case_ 3
print "3"
  Default_
print "default"
  Endsw_
  inkey chr$(13, 10, "bye")
  exit
end start

[habran]

jj2007 :t
It really works, I will test it more and come back to you

[habran]

jj2007, this macro is a peace of art
There is only need to fix an overflow. If the number is greater than the greatest case than it jumps in a wilderness.
Can you make it to work in 64 bit?

[jj2007]

There is only need to fix an overflow. If the number is greater than the greatest case than it jumps in a wilderness.

I don't understand. Can you post an example please?

[habran]

include \masm32\include\masm32rt.inc
include SwitchUnsafe.mac
.code
start:
  mov ecx, 18                    ;this will produce that jump
  Switch_ ecx, unsafe
  Case_ 0
   print "0"
  Case_ 3
   print "3"
  Default_
   print "default"
  Endsw_
  inkey chr$(13, 10, "bye")
  exit
end start

[jj2007]

Just delete the "unsafe", and it will be safe (but 4 bytes longer) :P

  m2m ecx, 18
  Switch_ ecx

[habran]

Thank you, jj2007 :t
Now, what about 64 bit? Are you CANDO CAN'TDO? ;)

[jj2007]

Here it is - test yourself 8)

[habran]

there is something wrong it throws this error:
1>simple.asm(251): error A2048: Operands must be the same size: 4 - 8

[habran]

mistake is somewhere here:

Code Select Expand

  @CatStr(<cmp >, tmp$, <, MbSw>, %MbSct, <L[4]>) ; max
  @CatStr(<mov rdx, MbSw>, %MbSct, <L>) ; min
  ifdifi <smode>, <unsafe>
@CatStr(<jg @MbSw>, %MbSct, <D>)
  endif
  @CatStr(<add rdx, >, tmp$)
  ifdifi <smode>, <unsafe>
@CatStr(<jl @MbSw>, %MbSct, <D>)
  endif
  @CatStr(<jmp MbSw>, %MbSct, <L[4*rdx+8]>)


[jj2007]

mistake is somewhere here:

Code Select Expand

  @CatStr(<cmp >, tmp$, <, MbSw>, %MbSct, <L[4]>) ; max


Yes, it probably needs some adjustments, e.g. [8] instead of [4] etc

[TWell]

Code Select Expand

include SwitchUnsafe64.mac
extern ExitProcess :proc

.data
s1 db "0",0
s3 db "3",0
sd db "default",0

.code
start:
  sub rsp, 40
  mov rcx, 18         ;this will produce that jump
  Switch_ ecx;, unsafe
  Case_ 0
   mov rcx, offset s1
  Case_ 3
   mov rcx, offset s3
  Default_
   mov rcx, offset sd
  Endsw_
  xor ecx, ecx
  call ExitProcess
end ;start

Code Select Expand

ml64 -c SwitchUnsafe64.asm
Microsoft (R) Macro Assembler (x64) Version 14.00.23506.0
Copyright (C) Microsoft Corporation.  All rights reserved.

Assembling: SwitchUnsafe64.asm
SwitchUnsafe64.asm(13) : error A2022:instruction operands must be the same size
Switch_(11): Macro Called From
  SwitchUnsafe64.asm(13): Main Line Code
SwitchUnsafe64.asm(13) : error A2022:instruction operands must be the same size
Switch_(15): Macro Called From
  SwitchUnsafe64.asm(13): Main Line Code
SwitchUnsafe64.asm(13) : error A2024:invalid operand size for instruction
Switch_(19): Macro Called From
  SwitchUnsafe64.asm(13): Main Line Code