On Wed, 17 Oct 2018 13:27:09 +0100 Tristan Williams <h...@tjnw.co.uk> wrote:
> On 17Oct18 10:25, Martin Nicholas via Amforth-devel wrote: > > Hi, > > > > I think that @ ! +! 2@ 2! d+! should disable interrupts on the AVR. > > Although it's possible to code around a variable being changed by an > > interrupt (using C@ C! for example), the 16-bit counter registers > > can't be dealt with in a similar way. Section 17.3 of the datasheet > > "Accessing 16-bit Registers" deals with all this. @ and ! do do the > > byte accesses in the right order, but an interrupt using the 16-bit > > registers associated with a particular counter will overwrite the > > "TEMP (8-bit)" register (see Figure 17-4). > > > > Cheers! > > > > > > Hello Martin, > > This page http://amforth.sourceforge.net/TG/AVR8.html sets out how > AmForth handles interrupts and I think it is relevant to your post. > > Earlier this year I wrote some forth[1] that used the word 1ms and it > was not running as I expected. I had not realised that the execution > of AmForth words written in assembler would not be interrupted. @ ! +! > are assembler words and so will not be interrupted. > > Tristan > > [1] > https://sourceforge.net/p/amforth/mailman/amforth-devel/?viewmonth=201806 > No, thie problem with 1ms is specific to 1ms. I suspect the tight inner loop is uninterruptable. It is: > sbiw Z, 1 > brne pc-1 Interrupts are enabled at all times (by APPLTURNKEY) unless you specifically disable them. Looking at the vanilla build at: amforth-6.7/appl/template/template.lst These words enable interrupts: +INT APPLTURNKEY. These disable: -INT. These temporarily disable interrupts: RP! !E @E (!I-NRWW). They are re-enabled before exit. That's it. Search for "cli" and "sei". When I have time I'll test my theory about 1ms. Atmel documentation is no help on this, although there are dark hints in the documentation for BRNE. Confirm interrupt status with: "hex 5f c@ ." Cheers! -- Regards, Martin Nicholas. E-mail: m...@mgn.org.uk. _______________________________________________ Amforth-devel mailing list for http://amforth.sf.net/ Amforth-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/amforth-devel
