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Groups > comp.lang.forth > #42084
| From | anton@mips.complang.tuwien.ac.at (Anton Ertl) |
|---|---|
| Newsgroups | comp.lang.forth |
| Subject | Re: old `leave` renamed to `exhaust` |
| Date | 2015-09-19 10:48 +0000 |
| Organization | Institut fuer Computersprachen, Technische Universitaet Wien |
| Message-ID | <2015Sep19.124814@mips.complang.tuwien.ac.at> (permalink) |
| References | (3 earlier) <2015Sep14.103356@mips.complang.tuwien.ac.at> <mt8f9i$qm3$1@speranza.aioe.org> <y7pior0acvxj.ch2dlom72stl$.dlg@40tude.net> <2015Sep15.171318@mips.complang.tuwien.ac.at> <mtieeo$h7v$1@speranza.aioe.org> |
"HAA" <someone@microsoft.com> writes:
>Anton Ertl wrote:
>>
>> The current looping constructs for negative stride in Gforth still
>> have one weakness, though:
>>
>> When walking backwards over an array addr u of cells, we would like to
>> start with addr u 1- cells + and end with addr, but that's relatively
>> cumbersome to express, e.g.:
>>
>> addr 1 cells - addr u 1- cells + ?do ... i ... 1 cells -loop
>>
>> or (less run-time efficiency)
>>
>> addr addr u cells + ?do ... i 1 cells - ... 1 cells -loop
>>
>> - anton
>
>Typically addr u will be constants and u > 1 which your program can exploit:
>
> 0 u 1- do ... i cells addr + ... -1 +loop
You need to replace 0 with -1 in order to be equivalent to the
variants above. Depending on the implementation and CPU, this may be
slower at run-time than the variants above.
- 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
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old `leave` renamed to `exhaust` Marcos Cruz <null_email_so_use_my_contact_page@programandala.net> - 2015-09-07 20:29 +0000
Re: old `leave` renamed to `exhaust` "HAA" <someone@microsoft.com> - 2015-09-08 14:52 +1000
Re: old `leave` renamed to `exhaust` Mark Wills <markwills1970@gmail.com> - 2015-09-08 00:57 -0700
Re: old `leave` renamed to `exhaust` Bernd Paysan <bernd.paysan@gmx.de> - 2015-09-08 15:19 +0200
Re: old `leave` renamed to `exhaust` Marcos Cruz <null_email_so_use_my_contact_page@programandala.net> - 2015-09-08 16:25 +0000
Re: old `leave` renamed to `exhaust` "HAA" <someone@microsoft.com> - 2015-09-09 11:39 +1000
Re: old `leave` renamed to `exhaust` Marcos Cruz <null_email_so_use_my_contact_page@programandala.net> - 2015-09-09 10:42 +0000
Re: old `leave` renamed to `exhaust` "HAA" <someone@microsoft.com> - 2015-09-10 14:05 +1000
Re: old `leave` renamed to `exhaust` Marcos Cruz <null_email_so_use_my_contact_page@programandala.net> - 2015-09-10 13:33 +0000
Re: old `leave` renamed to `exhaust` Coos Haak <chforth@hccnet.nl> - 2015-09-10 22:04 +0200
Re: old `leave` renamed to `exhaust` Coos Haak <chforth@hccnet.nl> - 2015-09-10 22:13 +0200
Re: old `leave` renamed to `exhaust` "HAA" <someone@microsoft.com> - 2015-09-11 13:14 +1000
Re: old `leave` renamed to `exhaust` Coos Haak <chforth@hccnet.nl> - 2015-09-11 12:30 +0200
Re: old `leave` renamed to `exhaust` "HAA" <someone@microsoft.com> - 2015-09-11 21:47 +1000
Re: old `leave` renamed to `exhaust` Bernd Paysan <bernd.paysan@gmx.de> - 2015-09-11 14:09 +0200
Re: old `leave` renamed to `exhaust` "HAA" <someone@microsoft.com> - 2015-09-12 11:29 +1000
Re: old `leave` renamed to `exhaust` "Elizabeth D. Rather" <erather@forth.com> - 2015-09-11 16:05 -1000
Re: old `leave` renamed to `exhaust` "HAA" <someone@microsoft.com> - 2015-09-14 12:25 +1000
Re: old `leave` renamed to `exhaust` "Elizabeth D. Rather" <erather@forth.com> - 2015-09-13 17:53 -1000
Re: old `leave` renamed to `exhaust` anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-09-14 08:33 +0000
Re: old `leave` renamed to `exhaust` "HAA" <someone@microsoft.com> - 2015-09-15 16:55 +1000
Re: old `leave` renamed to `exhaust` hughaguilar96@gmail.com - 2015-09-15 01:46 -0700
Re: old `leave` renamed to `exhaust` Coos Haak <chforth@hccnet.nl> - 2015-09-15 15:14 +0200
Re: old `leave` renamed to `exhaust` anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-09-15 15:13 +0000
Re: old `leave` renamed to `exhaust` hughaguilar96@gmail.com - 2015-09-15 16:13 -0700
Re: old `leave` renamed to `exhaust` jim.brakefield@ieee.org - 2015-09-15 17:05 -0700
Re: old `leave` renamed to `exhaust` hughaguilar96@gmail.com - 2015-09-15 18:35 -0700
Re: old `leave` renamed to `exhaust` "HAA" <someone@microsoft.com> - 2015-09-19 11:42 +1000
Re: old `leave` renamed to `exhaust` anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-09-19 10:48 +0000
Re: old `leave` renamed to `exhaust` "HAA" <someone@microsoft.com> - 2015-09-20 00:01 +1000
Re: old `leave` renamed to `exhaust` anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-09-19 15:02 +0000
Re: old `leave` renamed to `exhaust` "HAA" <someone@microsoft.com> - 2015-09-21 15:51 +1000
Re: old `leave` renamed to `exhaust` "Elizabeth D. Rather" <erather@forth.com> - 2015-09-15 08:45 -1000
Re: old `leave` renamed to `exhaust` "HAA" <someone@microsoft.com> - 2015-09-16 11:18 +1000
Re: old `leave` renamed to `exhaust` anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-09-16 06:10 +0000
Re: old `leave` renamed to `exhaust` "HAA" <someone@microsoft.com> - 2015-09-17 15:15 +1000
Re: old `leave` renamed to `exhaust` anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-09-17 06:04 +0000
Re: old `leave` renamed to `exhaust` Coos Haak <chforth@hccnet.nl> - 2015-09-11 14:16 +0200
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