Memorry allication

NZ_Design — Thu, 08 May 2008 09:09:09 GMT

Is there a reason for not being able to declear my memory allocation like this

BATTERY_RAM       INTO NO_INIT     0x200000'G TO 0x2FFFFF'G;   // CS1 BatteryRAM;

If I declear it as such GPage never changes an thus the 0xFFFF blocks of memory get corrupted as the data exceeds 0xFFFF.

But if I declear it like this.

BATTERY_RAM          INTO NO_INIT     0x200000'G TO 0x20FFFF'G;   // CS1 BatteryRAM;
BED_RAM                   INTO NO_INIT 0x210000'G TO 0x21FFFF'G;   // CS1 BatteryRAM;
EXTERNAL_RAM      INTO NO_INIT 0x220000'G TO 0x22FFFF'G;   // CS1 BatteryRAM;

It is fine.

If the first one should work if I have an array the covers 2 GPages does code warrior cope I am I safer to declear it the secound way.

Using a HCS12XDP512MAG processor

Code worrior IDE 5.7 and HCS(X)12 v4.5

Thanks

Re: Memorry allication

CompilerGuru — Thu, 08 May 2008 12:01:28 GMT

The S12X instruction set performs all address calculations on 16 bit only, it does not propagate overflows into the page.

LDX #FFFE
MOVB #0x0F, __GPAGE_ADR
GSTX 2,X

will write to 0xF0000'G, so the 2,X addition overflows and wraprs around.

Daniel

topic Memorry allication in Classic/Legacy CodeWarrior

Memorry allication

Re: Memorry allication