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Groups > comp.arch.embedded > #26849
| From | anton@mips.complang.tuwien.ac.at (Anton Ertl) |
|---|---|
| Newsgroups | comp.arch.embedded, comp.lang.forth |
| Subject | Re: MCU mimicking a SPI flash slave |
| Date | 2017-06-19 14:44 +0000 |
| Organization | Institut fuer Computersprachen, Technische Universitaet Wien |
| Message-ID | <2017Jun19.164441@mips.complang.tuwien.ac.at> (permalink) |
| References | (7 earlier) <oi0eo5$2fr$1@dont-email.me> <oi17eh$pgf$1@dont-email.me> <oi78d7$grp$1@dont-email.me> <oi7l7u$hgl$1@dont-email.me> <oi81sg$n55$1@dont-email.me> |
Cross-posted to 2 groups.
David Brown <david.brown@hesbynett.no> writes:
>I gave a list somewhere in another post. But my key "missing features"
>from Forth are good static checking, typing, methods of working with
>data of different sizes, safe ways to define and use structures, and
>ways to modularise the program.
>
>For example, take the "FLOOR5" function from the Wikipedia page:
>
>: FLOOR5 ( n -- n' ) DUP 6 < IF DROP 5 ELSE 1 - THEN ;
>
>
>The C version is:
>
>int floor5(int v) {
> return (v < 6) ? 5 : (v - 1);
>}
>
>
>Suppose the Forth programmer accidentally writes:
>
>: FLOOR5 ( n -- n' ) 6 < IF DROP 5 ELSE 1 - THEN ;
>
>It's an easy mistake to miss, and you've made a perfectly valid Forth
>word definition that will be accepted by the system. But now the
>comment does not match the usage. It would be entirely possible for the
>language to provide a formalised and standardised way of specifying
>input and output parameters in a way that most cases could be
>automatically checked by the tools. Conventionalised comments are /way/
>out of date as an aid to automated correctness checking.
As a proper programmer, you also write tests for your programs:
t{ 3 floor5 -> 5 }t
t{ 5 floor5 -> 5 }t
t{ 6 floor5 -> 5 }t
t{ 9 floor5 -> 8 }t
When you run this through "gforth test/ttester.fs", you get right
away:
:2: Stack underflow
t{ 3 >>>floor5<<< -> 5 }t
Backtrace:
$7F062B481EF0 lit
The backtrace points to one of the literals (6, 5, or 1, and actually
5 in this case), which is misleading; Gforth notices stack underflows
when the stack memory is accessed, and DROP does not access that
memory. But anyway, once you get that error message, it's pretty easy
to find the error.
Even if you run it on a system that does not catch all stack
underflows (e.g., gforth-fast test/ttester.fs), you get
WRONG NUMBER OF RESULTS: t{ 3 floor5 -> 5 }t
WRONG NUMBER OF RESULTS: t{ 5 floor5 -> 5 }t
WRONG NUMBER OF RESULTS: t{ 6 floor5 -> 5 }t
WRONG NUMBER OF RESULTS: t{ 9 floor5 -> 8 }t
A static checker might say that the DROP and the - access a value that
is not present in the stack effect, so they would be a little more
precise at pinpointing the problem, but stack depth issues are easy
enough that nobody found it worthwhile to write such a checker yet.
BTW, I wrould write this function as:
: floor5 ( n1 -- n2 ) 1- 5 max ;
>And then suppose you want this function to work with 32-bit values -
>regardless of the width of a cell on the target machine. Or 64-bit
>values on a 16-bit cell system.
No! I have had lots of portability problems for C code when porting
between 32-bit and 64-bit systems, thanks to the integer type zoo of
C. In Forth I have had very few such problems, thanks to the fact
that we only have cells and occasionally double-cells (and when you
get a double-cell program right on 32-bit systems, it also works on
64-bit systems). If you want a FLOOR5 variant that works for integers
that don't fit in a cell, you write DFLOOR5. And if it does not fit
in double cells (but would fit in 64 bits), you probably have the
wrong machine for what you are trying to do. C did not acquire 64-bit
integer types until 32-bit machines were mainstream.
- anton
--
M. Anton Ertl http://www.complang.tuwien.ac.at/anton/home.html
comp.lang.forth FAQs: http://www.complang.tuwien.ac.at/forth/faq/toc.html
New standard: http://www.forth200x.org/forth200x.html
EuroForth 2017: http://www.euroforth.org/ef17/
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MCU mimicking a SPI flash slave John Speth <johnspeth@yahoo.com> - 2017-06-14 10:44 -0700
Re: MCU mimicking a SPI flash slave Don Y <blockedofcourse@foo.invalid> - 2017-06-14 16:30 -0700
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-14 21:54 -0400
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-15 08:01 +0100
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-15 12:13 -0400
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-15 18:01 +0100
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-15 16:52 -0400
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-15 23:37 +0200
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-15 18:15 -0400
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-16 09:25 +0200
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-16 13:52 -0400
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-18 22:56 +0200
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-19 00:21 -0400
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-19 09:02 +0200
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-19 08:36 -0400
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-19 14:47 +0200
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-19 09:23 -0400
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-19 15:34 +0200
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-20 00:16 -0400
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-20 09:49 +0200
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-20 22:44 -0400
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-21 12:10 +0200
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-21 12:40 -0400
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-21 18:19 +0100
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-21 14:34 -0400
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-21 21:41 +0100
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-21 17:14 -0400
Re: MCU mimicking a SPI flash slave edward.ming.lee@gmail.com - 2017-06-21 13:54 -0700
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-15 23:33 +0100
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-15 23:12 -0400
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-16 07:05 +0100
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-16 02:27 -0400
Re: MCU mimicking a SPI flash slave Tim Wescott <seemywebsite@myfooter.really> - 2017-06-14 23:17 -0500
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-15 08:03 +0100
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-15 09:14 +0200
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-15 08:25 +0100
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-15 10:02 +0200
Re: MCU mimicking a SPI flash slave Reinhardt Behm <rbehm@hushmail.com> - 2017-06-15 16:25 +0800
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-15 10:32 +0200
Re: MCU mimicking a SPI flash slave Reinhardt Behm <rbehm@hushmail.com> - 2017-06-15 21:48 +0800
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-15 10:09 +0100
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-15 09:41 +0100
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-15 13:04 +0200
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-15 12:31 +0100
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-15 14:20 +0200
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-15 17:46 -0400
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-16 13:21 +0200
Re: MCU mimicking a SPI flash slave stephen@mpeforth.com (Stephen Pelc) - 2017-06-16 13:55 +0000
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-16 16:34 +0200
Re: MCU mimicking a SPI flash slave stephen@mpeforth.com (Stephen Pelc) - 2017-06-16 15:40 +0000
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-19 00:47 +0200
Re: MCU mimicking a SPI flash slave stephen@mpeforth.com (Stephen Pelc) - 2017-06-21 15:47 +0000
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-21 19:15 +0200
Re: MCU mimicking a SPI flash slave stephen@mpeforth.com (Stephen Pelc) - 2017-06-21 15:50 +0000
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-21 19:16 +0200
Re: MCU mimicking a SPI flash slave stephen@mpeforth.com (Stephen Pelc) - 2017-06-21 18:00 +0000
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-22 11:24 +0200
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-22 12:12 -0400
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-16 14:22 -0400
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-19 03:15 +0200
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-19 00:54 -0400
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-19 10:30 +0200
Re: MCU mimicking a SPI flash slave albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2017-06-19 12:54 +0200
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-19 13:49 +0200
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-19 09:28 -0400
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-19 09:19 -0400
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-19 16:23 +0200
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-19 23:57 -0400
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-20 12:36 +0200
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-20 08:20 -0400
Re: MCU mimicking a SPI flash slave anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-19 14:44 +0000
Re: MCU mimicking a SPI flash slave albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2017-06-19 21:39 +0200
Re: MCU mimicking a SPI flash slave Cecil Bayona <cbayona@cbayona.com> - 2017-06-19 14:59 -0500
Re: MCU mimicking a SPI flash slave albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2017-06-20 09:25 +0200
Re: MCU mimicking a SPI flash slave Cecil Bayona <cbayona@cbayona.com> - 2017-06-20 11:50 -0500
Re: MCU mimicking a SPI flash slave anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-20 12:37 +0000
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-19 22:59 +0200
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-20 00:12 -0400
Re: MCU mimicking a SPI flash slave Dimiter_Popoff <dp@tgi-sci.com> - 2017-06-20 10:25 +0300
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-20 10:44 +0200
Re: MCU mimicking a SPI flash slave dp <dp@tgi-sci.com> - 2017-06-20 02:36 -0700
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-20 11:25 +0100
Re: MCU mimicking a SPI flash slave Dimiter_Popoff <dp@tgi-sci.com> - 2017-06-20 13:49 +0300
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-20 12:54 +0100
Re: MCU mimicking a SPI flash slave Dimiter_Popoff <dp@tgi-sci.com> - 2017-06-20 16:09 +0300
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-20 15:24 +0100
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-20 17:46 +0100
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-20 22:28 +0200
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-21 00:58 +0100
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-21 13:08 +0200
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-20 16:28 +0200
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-20 12:58 +0200
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-20 12:57 +0200
Re: MCU mimicking a SPI flash slave Dimiter_Popoff <dp@tgi-sci.com> - 2017-06-20 14:19 +0300
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-20 16:19 +0200
Re: MCU mimicking a SPI flash slave anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-20 12:12 +0000
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-20 16:48 +0200
Re: MCU mimicking a SPI flash slave Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2017-06-20 21:16 +0100
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-20 23:15 +0200
Re: MCU mimicking a SPI flash slave Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2017-06-21 07:30 +0100
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-21 12:54 -0400
Re: MCU mimicking a SPI flash slave David Brown <david.brown@hesbynett.no> - 2017-06-21 19:29 +0200
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-21 15:05 -0400
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-21 21:34 +0100
Re: MCU mimicking a SPI flash slave "Elizabeth D. Rather" <erather@forth.com> - 2017-06-21 18:04 -1000
Re: MCU mimicking a SPI flash slave albert@cherry.spenarnc.xs4all.nl (Albert van der Horst) - 2017-06-22 10:26 +0200
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-22 11:56 -0400
Re: MCU mimicking a SPI flash slave stephen@mpeforth.com (Stephen Pelc) - 2017-06-22 09:20 +0000
Re: MCU mimicking a SPI flash slave Wasell <from_usenet@wasell.eu> - 2017-06-22 14:02 +0200
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-22 11:59 -0400
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-22 11:58 -0400
Re: MCU mimicking a SPI flash slave anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-22 08:19 +0000
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-19 09:53 +0100
Re: MCU mimicking a SPI flash slave Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-15 10:16 +0100
Re: MCU mimicking a SPI flash slave John Speth <johnspeth@yahoo.com> - 2017-06-15 13:56 -0700
Re: MCU mimicking a SPI flash slave Don Y <blockedofcourse@foo.invalid> - 2017-06-15 14:41 -0700
Re: MCU mimicking a SPI flash slave John Speth <johnspeth@yahoo.com> - 2017-06-15 15:08 -0700
Re: MCU mimicking a SPI flash slave Don Y <blockedofcourse@foo.invalid> - 2017-06-16 11:34 -0700
Re: MCU mimicking a SPI flash slave rickman <gnuarm@gmail.com> - 2017-06-15 18:20 -0400
Re: MCU mimicking a SPI flash slave edward.ming.lee@gmail.com - 2017-06-21 07:58 -0700
Re: MCU mimicking a SPI flash slave Walter Banks <walter@bytecraft.com> - 2017-06-19 12:23 -0400
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