How to import C variable in an assembly code in a .s file

I'm new of arm processor and I'd like to import a variable in a .s file the variable is definited in a c file:

#define INIT_VAR 1


extern uint32_t save_mem = INIT_VAR;

or better I need to write inside a memory address of that variable.

PS: I'm working witrh ARM cOrtex M0+ processor.

Also, It is possible to write with ldr instruction in a specified address a integer value?