🚀 go-pugleaf

beaurega@ireq.hydro.qc.ca (Denis Beauregard) writes:
>In the category : HLL with Assembly
>  Ross Ridge
>  64 bytes for a TSR counter
>
>Note : I have no Borland compiler on hand.  But, statements like
>#define get_strategy() (_AX=0x5800, INT21(), _AX)
>looks like inline functions.  What is doing _AX=0x5800 ?  Compiling
>this into "mov ax,$5800" ?  If true, this is inline!

No it's not.  _AX=0x5800 isn't assembler, it doesn't even look
like assembler.  But it was only used for convience, these functions
could easily have been written (more portability) like this:

	int
	get_strategy(void) {
		union REGS regs;

		regs.x.ax = 0x5800;
		intdos(&regs, &regs);
		return regs.x.ax;
	}

The only use of register pseudovariables that's required is at the
start of the isr funtion:

	_DS = _CS;

Again this isn't assembler, you can't even do that in assembler, as
"mov ds,cs" is illegal.  The compiler is has to take the statement,
expressed in C, of "assign the code segment register to the data 
segment register" and translate it into assembler.  It even has
a view choices of how to do this:

	push cs
	pop ds
or...
	mov ax,cs
	mov ds,ax

In the latter case it could use bx, cx, or dx instead of ax.  Maybe
si and di too, I dunno, I don't care.  I'm no 8086 assembler wiz,
in fact when I first used a statement like "_ES = _DS;" I didn't
even realize that it couldn't be translated into assembly as
one statement.

>My own entry : doing the key swapper in HLL + Inline.
>Let's presume I use the same loader as Ross' program.
>The result would give 48 bytes.  Compare with 160 bytes without assembly.
 
My loader can't create an TSR less than 64 bytes including the MCB because
parts of the new PSP are modified by MS-DOS while setting it up.

							Ross Ridge

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