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[avr-gcc-list] Accessing structures defined in ROM ?

From: Vincent Trouilliez
Subject: [avr-gcc-list] Accessing structures defined in ROM ?
Date: Mon, 26 Sep 2005 16:57:56 +0200

Hi list,

I defined a structure in ROM, and am having difficulties accessing it
using a pointer. Structure contains an integer and an array of strings.
Accessing the array works, but when I try to read the integer number
using the pointer, I don't get the correct value.... what am I doing
wrong ?

Compiler doesn't complain of anything, no errors no warning, but it
doesn't retrieve the expected value... :-/

I put a sample code below... any idea ?? I must be doing something wrong
again ! ;-)



Using: gcc 3.4.3 and libc 1.2.3


struct menu {
        uint8_t nb;
        char    desc[][20];


//definition for the main menu
const struct menu __ATTR_PROGMEM__ menu_main = {
        3,      //there are 3 entries in this menu
        "Error Codes",
        "Display Parameters",
        "Data Logging"

int main (void){

        uint8_t         i;
        const struct menu * p;

        p = &menu_main;

        i = pgm_read_byte( p->nb ); //should return 3, but doesn't...
        lcd_print_str( p->desc[2] ); //works fine


void lcd_print_str(const char * addr)
        char c;

        while( (c = pgm_read_byte(addr++)) )


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