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#ifndef HANDY_H
#define HANDY_H
#include <stddef.h>
#include <stdint.h>
#include <string.h>
/*
* Handy CPP defines and C inline functions.
*/
/* Evaluates to the number of items in array-type variable arr. */
#define ARRAYCOUNT(arr) (sizeof arr / sizeof arr[0])
#ifndef MIN
# define MIN(x, y) ((x) < (y) ? (x) : (y))
#endif
/** Stringify its argument. */
#define STRINGIFY(x) STRINGIFY_(x)
#define STRINGIFY_(x) #x
/* Error handling macros.
*
* These expect a zero = success, non-zero = error convention.
*/
/** Error: return.
*
* If the expression fails, return the error from this function. */
#define ER(expr) do { typeof (expr) err_ = (expr); if (err_) return err_; } while (0)
/** Error: goto.
*
* If the expression fails, goto x_err. Assumes defn of label
* x_err and 'error_type err'. */
#define EG(expr) do { err = (expr); if (err) goto x_err; } while (0)
/** Like memset(ptr, 0, len), but not allowed to be removed by
* compilers. */
static inline void mem_clean(volatile void *v, size_t len)
{
if (len)
{
memset((void *) v, 0, len);
(void) *((volatile uint8_t *) v);
}
}
/** Returns 1 if len bytes at va equal len bytes at vb, 0 if they do not.
* Does not leak length of common prefix through timing. */
static inline unsigned mem_eq(const void *va, const void *vb, size_t len)
{
const volatile uint8_t *a = va;
const volatile uint8_t *b = vb;
uint8_t diff = 0;
while (len--)
{
diff |= *a++ ^ *b++;
}
return !diff;
}
#endif
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