delay.h

来自「linux 内核源代码」· C头文件 代码 · 共 21 行

#ifndef __UM_DELAY_H
#define __UM_DELAY_H

#define MILLION 1000000

/* Undefined on purpose */
extern void __bad_udelay(void);

extern void __udelay(unsigned long usecs);
extern void __delay(unsigned long loops);

#define udelay(n) ((__builtin_constant_p(n) && (n) > 20000) ? \
	__bad_udelay() : __udelay(n))

/* It appears that ndelay is not used at all for UML, and has never been
 * implemented. */
extern void __unimplemented_ndelay(void);
#define ndelay(n) __unimplemented_ndelay()

#endif