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