ppage register & far pointer

Claudione — Tue, 16 Nov 2010 07:59:22 GMT

Hi.

In my project I have several files in C & assembler language .

I'm using a banked memory model and in an assembler file I wrote my assembler font tables.

Initially I din't have any problem because the fonts were in the fixed flash page.

But now (code increased) they are in the 31 page.

I need to get the right font pointer with this assembler funtion:

GetFontPtr:

ldx #Fnt_00 ;ix* = font 0

ldy 1,sp ;iy* = font code to use

cpy #0 ;is font type N° 0 ?

beq GetFontPtr01

ldx #Fnt_01 ;ix* = font 1

GetFontPtr01:

subd #32 ;subd space

lsld ;16 bit entry

leax d,x ;load effective addres from d

ldx 0, x ;low address

ldab PPAGE ;high address (PPAGE)

rtc

I modified the return convention and everything it's ok especially if and only if the GetFontPtr is in the same page of fonts.

But I want to keep my assembler function in page 30 and the font in page 31.

In this condition the instruction ldx 0,x get the right address, because the Fnt_00 and Fnt_01 tables are seen from linker and the address it's ok...but no PPAGE register !

Infact it is 30.The value where is the function and not the fonts.Clearly I don'thave the rigt pointer.

Simple example: if the table font has this address 318000 from ldx 0,x I get 8000 but the ppage reg is 30 not 31 !

I need to know to export the ppage value from my assembler file.

Is it possible in your opinion ? Or I have to write the functions in the same font file ?

I would not to do this.

Thanks a lot

Claudio

Re: ppage register & far pointer

CrasyCat — Tue, 16 Nov 2010 18:45:22 GMT

Hello

Only solution you have here is to go through a function which is allocated in non-banked flash to actually access the paged data (the font pointer in your case).

You cannot access a paged pointer from banked code.

Check how this is done in et run time libraries in module datapage.c.

CrasyCat

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ppage register & far pointer

Re: ppage register & far pointer