>body address of a created word

[Micke]

I am experimenting with FlashForth on the Atmega 328P and find it both fun and easy to use. One of the things I am doing is to convert an old Finite State Machine implementation to FlashForth. However, I am having trouble with this, getting an unexpected behavour. After some troubleshooting I have located the problem to an unexpected behaviour with the words CREATE and >BODY.

Basically, if I create a word like this:
create test-word 1 , 2 , 3 ,

and then execute:
test-word u.
' test-word >body u.

I would have expected to get the same address in both cases and be able to access the comma-ed values through that address. In both Gforth and SwiftForth the address is the same. In FlashForth, however, I get two very different addresses instead (736 and 32780, respectively, after an empty warm). Doing a memory dump, it seems that the first address is correct and that the one given by ' test-word >body is wrong. Therefore, it is difficult to access the comma-ed numbers later.

I am only using ram at the moment (but will need to create the FSM in eeprom or flash later), but still suspect that this has something to do with the different memory types supported by FlashForth and that I am doing something wrong. Can anyone explain why ' test-word >body gives the wrong address in this case and how I should do to access the correct one instead?

The FlashForth version that I am using is FlashForth 5 Atmega 328 13.01.2019.

Thanks!

Mikael

[Mikael Nordman]

Hej,
Gforth works like traditional ram based forths usually do.

The behaviour is caused by the virtualizing of the memory types.
The value in the body of the created word is a pointer to the actual data area.
This is necessary to store the address of the data area permanently in flash.

Executing a created word actually performs (in optimized machine code)

' created-word >body @

create puppu  ok<$,ram> 
puppu  ok<$,ram> 338 
' puppu >body  ok<$,ram> 338 8e9a 
@  ok<$,ram> 338 338 

flash create foobar  ok<$,flash> 
foobar  ok<$,flash> 8eac 
' foobar >body  ok<$,flash> 8eac 8eaa 
@  ok<$,flash> 8eac 8eac 

eeprom create barfoo  ok<$,eeprom>
barfoo  ok<$,eeprom> 90c 
' barfoo >body  ok<$,eeprom> 90c 8eba 
@  ok<$,eeprom> 90c 90c 

[Mikael Nordman]

I have updated >BODY to return the data field address.
So now >BODY returns the same address as a created word.