How to modify x86 swi instruction/statement to include other register value +

[Wall-AF]

In 16-/32-bit x86 processors lots of interrupts are shown in the decompiled result as x = (code *)swi(0xNN);. Where is this generated? I'd like to at least add a few parameters to this, eventually replacing it with proper descriptive function calls!

[GhidorahRex]

These interrupts are in ia.sinc under the :INT constructors. Mostly :INT imm8.

If you wanted to do a custom one you would overload the constructor like this:

define pcodeop doTheThing;
:INT imm8       is vexMode=0 & byte=0xcd; imm8                      { tmp:1 = imm8; intloc:$(SIZE) = swi(tmp); call [intloc]; }
:INT imm8       is vexMode=0 & byte=0xcd; imm8=0xff           { doTheThing(); }

[Wall-AF]

@GhidorahRex sorry for being thick, but:

1. how/where do I then define doTheThing; and
2. how do I add other registers to limit/define that call?

E.g., how would this

INT 21,57 - Get/Set File Date and Time Using Handle

	AH = 57h
	AL = 00  get date and time
	   = 01  set date and time
	   = 02  ??? (DOS 4.0+ undocumented)
	   = 03  ??? (DOS 4.0+ undocumented) 
	   = 04  ??? (DOS 4.0+ undocumented)
	BX = file handle
	CX = time to set (if setting)
	DX = date to set (if setting)
	ES:DI = pointer to buffer to contain results

	on return:
	AX = error code if CF set  (see  [DOS ERROR CODES](https://stanislavs.org/helppc/dos_error_codes.html))
	CX = file time (if reading, see below)
	DX = file date (if reading, see below)

	Time encoding:

	|F|E|D|C|B|A|9|8|7|6|5|4|3|2|1|0|  Time in CX
	 | | | | | | | | | | | `------------  two second incr (0-29)
	 | | | | | `-----------------------  minutes 0-59)
	 `--------------------------------  hours (0-29)

	Date Encoding

	|F|E|D|C|B|A|9|8|7|6|5|4|3|2|1|0|  Date in DX
	 | | | | | | | | | | | `------------  day (1-31)
	 | | | | | | | `-------------------  month (1-12)
	 `--------------------------------  year - 1980

become say
SetFileDate(time,date) or {time, date} GetFileDate()
Obviously {time, date} would become a struct, but as it returns using CX&DX that complicates things somewhat! (I assume it'd need its own calling convention, is that correct?

[GhidorahRex]

You would probably just want to define it as a pcodeop. This one is tricky because it's doing a get/set depending on the value of AL, but maybe something like this:

define pcodeop GetFileDate;
:INT imm8       is vexMode=0 & byte=0xcd; imm8=0x21           {
  local datetime:4 = GetSetFileDate(AL, BX, CX, DX);
  CX = (zext(AL == 0) * datetime[0,16]) + (zext(AL == 1) * CX);
  DX =  (zext(AL == 0) * datetime[16,16]) + (zext(AL == 1) * DX);
}

This also completely ignores the whole result buffer and the AX error codes. Just trying to give a simple example.

[Wall-AF]

Are you suggesting replacing
:INT imm8 is vexMode=0 & byte=0xcd; imm8 { tmp:1 = imm8; intloc:$(SIZE) = swi(tmp); call [intloc]; }
or adding?
How does this affect other int21 calls? Can(/how do) you add the likes of AL (or another reg) into the mix to distinguish different calls, or is this unavailable currently?
(I don't want to break anything!!!)

[Wall-AF]

The sleigh compiler didn't like adding:

define pcodeop GetFileDate;
:INT imm8       is vexMode=0 & byte=0xcd; imm8=0x21           {
  local datetime:4 = GetSetFileDate(AL, BX, CX, DX);
  CX = (zext(AL == 0) * datetime[0,16]) + (zext(AL == 1) * CX);
  DX =  (zext(AL == 0) * datetime[16,16]) + (zext(AL == 1) * DX);
}

[GhidorahRex]

Sorry, there's two issues - one the pcodeop needs to match the name defined. Two, you can't put a constraint on a bitpattern and use it as an operand. An easy fix here is:

define pcodeop GetSetFileDate;
:INT imm8       is vexMode=0 & byte=0xcd; imm8 & simm8=0x21           {
  local datetime:4 = GetSetFileDate(AL, BX, CX, DX);
  CX = (zext(AL == 0) * datetime[0,16]) + (zext(AL == 1) * CX);
  DX =  (zext(AL == 0) * datetime[16,16]) + (zext(AL == 1) * DX);
}

[Wall-AF]

@GhidorahRex trying your fix from above (with or without removing the original :INT imm8) the sleigh compiler errored with this:

> Task :x86:sleighCompile FAILED
Compiling .\data\languages\x86-64.slaspec:
ia.sinc:3191: Constraining currently undefined operand: imm8
Unrecoverable error(s), halting compilation
ghidra.sleigh.grammar.BailoutException: Pattern equation parsing returned null
        at ghidra.sleigh.grammar.SleighCompiler.pequation(SleighCompiler.java:4372)
        at ghidra.sleigh.grammar.SleighCompiler.pequation(SleighCompiler.java:4174)
        at ghidra.sleigh.grammar.SleighCompiler.bitpattern(SleighCompiler.java:3617)
        at ghidra.sleigh.grammar.SleighCompiler.constructor(SleighCompiler.java:3469)
        at ghidra.sleigh.grammar.SleighCompiler.constructorlike(SleighCompiler.java:3028)
        at ghidra.sleigh.grammar.SleighCompiler.constructorlikelist(SleighCompiler.java:3421)

        at ghidra.sleigh.grammar.SleighCompiler.withblock(SleighCompiler.java:3239)
        at ghidra.sleigh.grammar.SleighCompiler.constructorlike(SleighCompiler.java:3018)
        at ghidra.sleigh.grammar.SleighCompiler.root(SleighCompiler.java:482)
        at ghidra.pcodeCPort.slgh_compile.SleighCompile.run_compilation(SleighCompile.java:1835)
        at ghidra.pcodeCPort.slgh_compile.SleighCompileLauncher.runMain(SleighCompileLauncher.java:217)
        at ghidra.pcodeCPort.slgh_compile.SleighCompile.main(SleighCompile.java:1891)
Compiling .\data\languages\x86.slaspec:
ia.sinc:3191: Constraining currently undefined operand: imm8
Unrecoverable error(s), halting compilation
ghidra.sleigh.grammar.BailoutException: Pattern equation parsing returned null
        at ghidra.sleigh.grammar.SleighCompiler.pequation(SleighCompiler.java:4372)
        at ghidra.sleigh.grammar.SleighCompiler.pequation(SleighCompiler.java:4174)
        at ghidra.sleigh.grammar.SleighCompiler.bitpattern(SleighCompiler.java:3617)

        at ghidra.sleigh.grammar.SleighCompiler.constructor(SleighCompiler.java:3469)
        at ghidra.sleigh.grammar.SleighCompiler.constructorlike(SleighCompiler.java:3028)
        at ghidra.sleigh.grammar.SleighCompiler.constructorlikelist(SleighCompiler.java:3421)
        at ghidra.sleigh.grammar.SleighCompiler.withblock(SleighCompiler.java:3239)
        at ghidra.sleigh.grammar.SleighCompiler.constructorlike(SleighCompiler.java:3018)
        at ghidra.sleigh.grammar.SleighCompiler.root(SleighCompiler.java:482)
        at ghidra.pcodeCPort.slgh_compile.SleighCompile.run_compilation(SleighCompile.java:1835)
        at ghidra.pcodeCPort.slgh_compile.SleighCompileLauncher.runMain(SleighCompileLauncher.java:217)
        at ghidra.pcodeCPort.slgh_compile.SleighCompile.main(SleighCompile.java:1891)
0 languages successfully compiled

I don't understand SLEIGH enough to even investigate errors of any kind! What do I need to do to make it work?