Linked List From Flash memory transitioning into Ram - c

Question

Alright so I am new here so please be easy on me :)
I am currently developing on a uC in C and using linked lists to create structures every time the user wants to create one. Example:
typedef struct {
char* dataitem;
struct listelement *link;
int16_t wordSize;
int16_t (*libWord)[Q];
char gpioValue;
}listelement;
listelement * AddItem (listelement * listpointer, char* name, int16_t size, int16_t wordLength, int16_t (*words)[L][Q]) {
// returns listPointer at the beginning of list
listelement * lp = listpointer;
listelement * listPointerTemp;
char ErrorHandler = NULL;
// are we at the end of the list?
if (listpointer != NULL) {
// move down to the end of the list
while (listpointer -> link != NULL)
listpointer = listpointer -> link;
listPointerTemp = listpointer;
listpointer -> link = (struct listelement *) malloc (sizeof (listelement));
// on fail end links becomes NULL already above
if(listpointer -> link != NULL){
listpointer = listpointer -> link;
listpointer -> link = NULL;
listpointer -> wordSize = wordLength;
listpointer -> dataitem = (char*) malloc ((size + 1)*sizeof(char));
if(listpointer -> dataitem != NULL){
for(int i=0; i<size ; i++){
listpointer -> dataitem[i] = name[i];
}
listpointer -> dataitem[size] = NULL;
listpointer -> libWord = (int16_t(*)[Q])malloc(wordLength*Q*sizeof(int16_t));
if(listpointer -> libWord != NULL){
for (int16_t row=0 ; row < wordLength ; row++){
for (int col=0 ; col < Q ; col++){
listpointer -> libWord[row][col] = words[0][row][col];
}
}
ErrorHandler = 1;
}else{
free(listpointer->dataitem);
free(listpointer);
listPointerTemp -> link = NULL;
}
}else{
free(listpointer);
listPointerTemp -> link = NULL;
}
}
if(ErrorHandler == NULL){
//failure
usart_write_line(&AVR32_USART0,"\r\n--------------------------------------------\r\n");
usart_write_line(&AVR32_USART0,"Ran out of Memory! Word not created.\r\n");
usart_write_line(&AVR32_USART0,"\r\n--------------------------------------------\r\n");
}
return lp;
}
else {
listpointer = (struct listelement *) malloc (sizeof (listelement));
if(listpointer != NULL){
listpointer -> link = NULL;
listpointer -> wordSize = wordLength;
listpointer -> dataitem = (char*) malloc (sizeof(name));
if(listpointer -> dataitem != NULL){
for(int16_t i=0; i<size ; i++){
listpointer -> dataitem[i] = name[i];
}
listpointer -> libWord = (int16_t(*)[Q])malloc(wordLength*Q*sizeof(int16_t));
if(listpointer -> libWord != NULL){
for (int16_t row=0 ; row < wordLength ; row++){
for (int col=0 ; col < Q ; col++){
listpointer -> libWord[row][col] = words[0][row][col];
}
}
ErrorHandler = 1;
}else{
free(listpointer->dataitem);
free(listpointer);
listPointerTemp -> link = NULL;
}
}else{
free(listpointer);
listPointerTemp -> link = NULL;
}
}
if(ErrorHandler == NULL){
//failure
usart_write_line(&AVR32_USART0,"\r\n--------------------------------------------\r\n");
usart_write_line(&AVR32_USART0,"Ran out of Memory! Word not created.\r\n");
usart_write_line(&AVR32_USART0,"\r\n--------------------------------------------\r\n");
}
return listpointer;
}
}
So now I want to add structures already stored in memory using const as such:
// start to include words, then merge into structures for user_interactive to link lists with
//////////////////////////////////////////////////////////////////////////////////////////////////
// TRON
//////////////////////////////////////////////////////////////////////////////////////////////////
const int16_t libWord1[10][Q] = { {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15},
{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15},
{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15},
{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15},
{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15},
{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15},
{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15},
{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15},
{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15},
{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15}, };
const char dataitem1[4] = {'T','r','o','n'};
const int16_t wordSize1 = 10, nameSize = 4;
//////////////////////////////////////////////////////////////////////////////////////////////////
// eventually change NULL to next link in link list
const listelement Tron = { dataitem1, NULL, wordSize1, libWord1, 0x00 };
Alright so even if you skip reading all of that, I was just wondering what a good way of somehow create constant structs (do I have to create a new structure format just for const types?) and then link the beginning of the RAM linked lists when user creates first one to the Flash portion of linked lists created on startup?
Let me know if more information is needed. I tried not to put too much code on here.
Thanks!
So here is the change and the effects:
// start to include words, then merge into structures for user_interactive to link lists with
//////////////////////////////////////////////////////////////////////////////////////////////////
// TRON
//////////////////////////////////////////////////////////////////////////////////////////////////
const int16_t libWord1[10][Q] = { {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15},
{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15},
{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15},
{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15},
{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15},
{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15},
{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15},
{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15},
{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15},
{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15}, };
//////////////////////////////////////////////////////////////////////////////////////////////////
// ON
//////////////////////////////////////////////////////////////////////////////////////////////////
const int16_t libWord2[10][Q] = { {15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1},
{15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1},
{15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1},
{15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1},
{15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1},
{15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1},
{15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1},
{15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1},
{15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1},
{15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1}, };
//////////////////////////////////////////////////////////////////////////////////////////////////
// eventually change NULL to next link in link list
const listelement* Tron = { "Tron", NULL, 10, libWord1, 0x00 };
// next element links to Tron . . .
const listelement* On = { "On", Tron, 10, libWord2, 0x01 };
// next element links to On . . . and so on . . .
listelement* constLinkInit(void){
return On;
}
I know I didn't do your global array of structs but ignoring that and passing the last struct to this guy in a nother file using a function.
listelement *listpointer;
// initially listpointer is initialized to NULL but now set to end of link list of FLASH
listpointer = constLinkInit();
And the going to print links like I had been doing for user defined structs dynamically (which had worked) fails when pointing to the next link even though the address passed to listpointer (On) is correct.
void PrintQueue (listelement * listpointer) {
usart_write_line(&AVR32_USART0,"\r\n--------------------------------------------\r\n");
if (listpointer == NULL){
usart_write_line(&AVR32_USART0,"queue is empty!\r\n");
}else{
//usart_write_line(&AVR32_USART0," Word List \r\n");
//usart_write_line(&AVR32_USART0,"--------------------------------------------\r\n");
while (listpointer != NULL) {
//usart_write_line(&AVR32_USART0, listpointer -> dataitem);
//usart_write_line(&AVR32_USART0,"\r\n");
//writeCOM_int_array(listpointer -> libWord , listpointer -> wordSize);
listpointer = listpointer -> link; // <---- FAILS HERE
}
}
usart_write_line(&AVR32_USART0,"\r\n--------------------------------------------\r\n");
}
When pointing to the next link it goes to the wrong address . . .
Thanks for the help!

Answer 1

Something like this should work:
#include <stdlib.h>
#include <stdint.h>
#define Q 5
typedef struct {
char *dataitem;
struct listelement *link;
int16_t wordSize;
int16_t (*libWord)[Q];
char gpioValue;
} listelement;
int16_t zzz[Q] = { 11, 22,33,44,55};
listelement global_array[] =
{{ "Sron", global_array+1, 2, zzz , 0 }
,{ "Tron", global_array+2, 2, zzz , 0 }
,{ "Uron", global_array+3, 2, zzz , 0 }
,{ "Vron", NULL , 2, zzz , 0 }
};