?? delay.h
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#ifndef _LINUX_DELAY_H#define _LINUX_DELAY_H/* * Copyright (C) 1993 Linus Torvalds * * Delay routines, using a pre-computed "loops_per_second" value. */extern unsigned long loops_per_sec;extern __inline__ void __delay(int loops){ __asm__(".align 2,0x90\n1:\tdecl %0\n\tjns 1b": :"a" (loops):"ax");}/* * division by multiplication: you don't have to worry about * loss of precision. * * Use only for very small delays ( < 1 msec). Should probably use a * lookup table, really, as the multiplications take much too long with * short delays. This is a "reasonable" implementation, though (and the * first constant multiplications gets optimized away if the delay is * a constant) */extern __inline__ void udelay(unsigned long usecs){ usecs *= 0x000010c6; /* 2**32 / 1000000 */ __asm__("mull %0" :"=d" (usecs) :"a" (usecs),"0" (loops_per_sec) :"ax"); __delay(usecs);}#endif
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