[HP48] Memory Management

[Bruno]

Thanks for your very accurate answers

David: Yes, 'builtin ROM routines' mean SysRPL/ASM entry points, not User RPL.
Thank to explained the 3 ways to handle objects, this is much clear for me now !

Claudio: Wow, this is very interesting, indeed this is the 'easiest' way to expand an object in UOA, but as you say, also risky.
I want to measure the trade off, so I've studied a little bit the RRP structure this weekend, and if I'm right,
I can summarize your method in these few steps:

1. Move destination object 'A' at the end (in memory) of the current directory.
2. Create EXTRA variable of size: (object to insert in 'A') - (2.5 bytes of 'A' offset field) - ('EXTRA' Name Length) - (2*1 bytes of EXTRA name length fields)
   • Q -> Why the HP48 need the name length field to be present before AND after the name field ???
   • This is also true for Backup and Library objects. Curious...
     
3. (3 or 4?)- Now 'EXTRA' is after 'A' in memory, and is the last variable of the current directory.
   • So, we need to update the last RRP's offset field (after 'EXTRA' variable) to skip 'EXTRA' and point directly to 'A'
   • Thus, 'A' became again the last variable of the current directory. 'EXTRA' becoming a ghost variable.
     
4. (4 or 3?)- Expand 'A' to "engluf" 'EXTRA' and insert the new object in 'A'
   

That's All ?

Bruno