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- Dictionaryvolatile/ˈvɒlətʌɪl/
adjective
- 1. (of a substance) easily evaporated at normal temperatures: "volatile solvents such as petroleum ether, hexane, and benzene" Similar
- 2. liable to change rapidly and unpredictably, especially for the worse: "the political situation was becoming more volatile" Similar Opposite
noun
- 1. a volatile substance.
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Oct 29, 2008 · Volatile provides very few guarantees about the behavior of the variable. It should be considered non-portable for any situation outside its very narrow scope. Volatile variable access should be encapsulated inside helper functions and volatile function parameters or returns should be avoided. The situations where volatile should be used are:
Jun 19, 2023 · The volatile keyword in C++ was inherited it from C, where it was intended as a general catch-all to indicate places where a compiler should allow for the possibility that reading or writing an object might have side-effects it doesn't know about. Because the kinds of side-effects that could be induced would vary among different platforms, the Standard leaves the question of what allowances to ...
typedef struct{ volatile uint8_t bar; } foo_t; foo_t foo_inst; I recognize that declaring a pointer-typed variable as volatile (e.g. volatile uint8_t * foo) merely informs the compiler that the address pointed-to by foo may change, while making no statement about the values pointed to by foo.
Sep 13, 2013 · It casts x as a volatile unsigned int pointer, and then dereferences that pointer to get the value of what x "points" to. Note that x doesn't actually need to be declared as a pointer, it could as well be a literal integer that is then treated as an address to somewhere in memory.
Jan 13, 2016 · Analyzing (*((volatile uint32_t *)0x40000000)) 0x40000000 is the address of register in your micro memory map; the register is 32 bits wide, that means must be uint32_t * volatile is added to tell compile to avoid to optimize that variable because of could change, for example, in an interrupt routine.
Nov 29, 2013 · @shodanex taking the address of a volatile variable will return a pointer to volatile, but if you intent to save that address in another variable then it also needs to carry volatile. &UART1 has type volatile UART *, but UART * hw = &UART1 will invoke a typecast into a pointer to non-volatile - here you need to write volatile UART * hw = &UART1.
Sep 16, 2008 · A volatile write is like an output operation (like printf or a use of cout): the value seems to be communicated outside of the program, so if the value depends on a computation, it needs to be finished before. So a pair of volatile read/write can be used to tame benchmarks and make time measurement meaningful.
So volatile char * x means 'x' is a pointer to a volatile char. while char volatile * x means that 'x' is a volatile pointer to a char. The difference in pactice is that when accessing x[0], in the first case, the value at x[n] needs to be read on each appearance in the source code (e.g. twice in a = x[n]*x[n])
Jun 11, 2009 · Just a warning on the C/C++ volatile keyword. Unless you know what you are doing you should never use it. C/C++ volatile != java/C# volatile volatile does not help in threaded code unless you really know what you are doing, you need to use C++0x atomic template (or something similar).
Oct 10, 2013 · Mapping a struct with bit-field members to hardware really seems to be a bad approach. So, to eliminate that I'll use one of the following instead as a pointer to the volatile memory address, #define PeripheralBase ((uint32_t volatile *)BASE) or . uint32_t volatile *const peripheral_base = (uint32_t *) BASE;
