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[avr-chat] Forcing C++ object instances to certain memory locations
From: |
Rick Mann |
Subject: |
[avr-chat] Forcing C++ object instances to certain memory locations |
Date: |
Sat, 5 Feb 2011 03:14:16 -0800 |
As part of an experiment I'm conducting in creating a C++ wrapper around AVR
hardware, I'd like to get C++ objects I've instantiated to live in certain
parts of the address space.
I have an AVRPort object that looks something like this (simplified):
class
AVRPort
{
public:
AVRRegisterT mPin;
AVRRegisterT mDirection;
AVRRegisterT mPort;
typedef volatile uint8_t AVRRegisterT;
// methods...
};
The PIN, DDR, and PORT registers for port A live at 0x0000, 0x0001, and 0x0002.
Now, I can access port A successfully via my class by defining this:
#define gPortA ((AVRPort*) 0x00)
#define gPortB ((AVRPort*) 0x03)
But I'd much rather define it like this:
extern AVRPort PortA;
extern AVRPort PortB;
...
AVRPort PortA;
AVRPort PortB;
and have it end up in the right place in memory. It seems like it should be
possible, using a linker script, to put it in the right section.
Is this possible? My current Makefile doesn't seem to use an explicit linker
script, and it's working fairly well, so I'm hesitant to jump in there and
break everything by trying to craft one. I'm using a Makefile that came with
the ChibiOS AVR port.
Suggestions much appreciated. Thanks!
--
Rick
- [avr-chat] Forcing C++ object instances to certain memory locations,
Rick Mann <=