Erich Waelde <ew.fo...@nassur.net> writes: > Hi Enoch, > > since you asked for comments ...
I certainly do! > On 02/13/2013 05:38 AM, Enoch wrote: >> Hello Matthias and all, >> >> I'd like to see this forum also offering code snippets, so here's my >> first humble attempt of harnessing the atomic bit manipulation >> instructions. >> >> : port:hi ( portadr bitno -- ) \ SBI >> swap $20 - 3 lshift or $9A00 or code , end-code >> ; >> >> : port:lo ( portadr bitno -- ) \ CBI >> swap $20 - 3 lshift or $9800 or code , end-code >> ; >> >> example: >> >> PORTB 7 port:hi green.hi >> PORTB 7 port:lo green.lo >> > > So you want to set or clear a bit in some register. > > What is wrong with the words found in bitnames.frt? > > include lib/bitnames.frt > PORTB 7 portpin: green > > and later > > green pin_output > green high > \ do something here > green low SBI/CBI can change bits in the 0..31 I/O range without needing a -int / +int protection. avr-gcc, for example, would use SBI when compiling PORTA |= _BV(0); > Sure, bitnames is doing read+modify+write on the memory mapped > location of the register, while your solution uses sbi/cbi which > does not work on the memory mapped location (hence $20 - ). > But what exactly is better with using sbi/cbi? That sbi/cbi > cannot be interrupted once the instruction is executing? But > all the instructions leading up to the sbi/cbi can be > interrupted, can't they? Do I miss the entire motivation of > the code snippet? Would you dare to enlighten me?? Well, let's try the following indirect argument: Atmel thought these instructions to be important enough to "spend" 2^10 opcodes out of their precious 2^16 RISC range. Don't we need to respect that engineering decision by suitable Amforth words? > As Matthias pointed out elsewhere: your snippet is intersting, > because assembly instructions are coded in at compile time > without loading the full assembler. That I can see. Yes, that DIY assembly approach can do things which lib/assembler.frt may find difficult to follow :-) Regards, Enoch. > > Cheers, > Erich > > ------------------------------------------------------------------------------ > Everyone hates slow websites. So do we. > Make your web apps faster with AppDynamics > Download AppDynamics Lite for free today: > http://p.sf.net/sfu/appdyn_d2d_feb ------------------------------------------------------------------------------ Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_d2d_feb _______________________________________________ Amforth-devel mailing list for http://amforth.sf.net/ Amforth-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/amforth-devel
