gnupic: Re: [gnupic] gpsim/gpasm assertions
Subject:
Re: [gnupic] gpsim/gpasm assertions
From:
Craig Franklin ####@####.####
Date:
22 May 2005 04:44:47 +0100
Message-Id: <42900084.1000802@users.sourceforge.net>
Scott Dattalo wrote:
>I've just added preliminary support for simulation assertions.
>(allow a few hours for the public CVS cache to be updated).
>
>The syntax in gpasm is:
>
> .direct "A" "expression"
>
>
>
I created some macros last year to simplify using .direct. They are
located in coff.inc.
Here are the relevant sections:
; Assertion
.assert macro x
.direct "a", x
endm
; Simulator Command
.sim macro x
.direct "e", x
endm
; Printf Command
.print macro x
.direct "f", x
endm
; Log Command
.log macro x
.direct "l", x
endm
The first one is what Scott implemented in gpsim. So you can:
.assert "var1==5"
>Where the quoted expression can be any legal gpsim expression. The quotes
>are required.
>
>This directive associates an expression with a program memory address.
>When gpsim simulates the instruction at the address, the expression will
>be evaluated. If the expression evaluates to true, then gpsim will halt.
>Note that gpasm will not parse the expression. So if there's a syntax
>error, you won't know until you start the simulation.
>
>The expression must be a boolean expression and the syntax is identical to
>C's. By boolean I mean that when evaluated, the expression must return
>true or false. Here's are a few examples that can be found in
>regression/assertions/assertions.asm:
>
>
> clrf var1
> clrf var2
> clrf var3
>
> ; var1 and var2 have just been cleared, so the following two
> ; assertions should fail
>
> .direct "A", "var1==5"
> nop
> .direct "A", "var2==6"
> nop
>
> ; compound expression
> .direct "A", "var2!=0 || var1!=0"
> nop
>
>Note, currently you cannot write:
>
> .direct "A", "var2" ; break if var2 is non zero
> nop
>
>Instead, explicitly check for non-zero
>
> .direct "A", "var2!=0" ; break if var2 is non zero
> nop
>
>
>One exception is a null expression. If you write:
>
> .direct "A", ""
> nop
>
>This assertion will always be true. This is identical to a break point.
>
>----
>
>This is the first real pass at simulation assertions - I'd appreciate any
>feed back. Also, I expect to make some changes/improvements.
>
>
>
Here was the gputils announcement:
http://www.linuxhacker.org/cgi-bin/ezmlm-cgi?1:mss:3396:200410:lifmjfnhofnjoddpaopp
gpasm puts the .direct into its output COFF files. gplink then writes
the symbols to its output COD file. So you can only use this feature in
relocatable mode. I did nothing to preclude using absolute mode, just
didn't take the time to add the feature.
>Scott
>
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