[Question] Question about the rule of VP and SP address spacing ?

jhpark

Hi, I got lots of helps and thanks for all !

I am in the process of setting up the Variable Pointer (VP) and the Screen Pointer (SP) addresses.
While I understand the general principles behind their usage,
I am seeking clarification on why specific address spacing is required between the VP and SP addresses.

I've noticed that in many examples and tutorials,
a certain amount of address spacing is deliberately maintained between VP and SP addresses.
Could you please explain the technical reasons behind this requirement ?

DWIN_LZ

SP records the various properties set by the display control and also occupies the variable address. Therefore, after setting the SP address, attention should be paid to the interval, usually 0x10 addresses, when setting VP or SP for new controls in the future

Serena

The VP address and SP address share the same address range, which is distinguished to avoid conflicts caused by pointer address confusion, resulting in characters not being displayed, incorrect position display, and abnormal data display etc.

jhpark

Thanks for your answers, DWIN_LZ and  Serena !

I see that I should provide some more range between the VP address,
and it's depend on my data size of VP at Control.

For example, if I'm using <Text Display> and set the length to 32
I should skip 32 x 2 bytes for finding the next VP address.

But, how I can guess about SP address ?
Is there any length (or else) on it ?

DWIN-ARK

jhpark 发表于 2023-7-13 17:53
Thanks for your answers, DWIN_LZ and  Serena !

I see that I should provide some more range between ...

dear，
SP address needs to be calculated according to the address length describing the control property. In order to be compatible with a maximum control property, different controls can be separated by 0x10 (16) addresses, such as 0x8000 for the first control and 0x8010 for the next one.

jhpark

DWIN-ARK 发表于 2023-7-13 21:25
dear，
SP address needs to be calculated according to the address length describing the control pro ...

Thanks DWIN-ARK, and I see !!