Doubt regarding the volatile keyword

What i understood about volatile keyword

(1)volatile unsigned char * ADC_address;
ADC_address is a pointer which stores a volatile unsigned character .

(2)volatile unsigned int ADC_voltage = 0;
ADC_voltage is volatile unsigned integer variable ,

(3)volatile unsigned char * ADC_REAL_ADDRESS;
ADC_REAL_ADDRESS = (volatile unsigned char *)STA_MEMORY_BASE;
Typecasting STA_MEMORY_BASE to volatile unsigned char pointer and assigned to ADC_REAL_ADDRESS.

If I wrong means please correct me.


(4)Can anyone explain the below statements
#define PINSEL_BASE_ADDR 0xE002C000
#define PINSEL0 (*(volatile unsigned long *)(PINSEL_BASE_ADDR + 0x00))

what I understood is (volatile unsigned long *)(PINSEL_BASE_ADDR + 0x00) in this statement (PINSEL_BASE_ADDR + 0x00) is type casted to volatile unsigned long pointer. But (*(volatile unsigned long *)(PINSEL_BASE_ADDR + 0x00)) , what is for the starting star(dereferencing operator) after first bracket.

The definition:

Takes the base address and dereferences it. Allowing you to write code such as:


The +0x00 offset has no effect of course but is presumably used to be consistent with the definitions of other registers (PINSEL1 perhaps?).