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/* * Precise Delay Loops for i386 * * Copyright (C) 1993 Linus Torvalds * Copyright (C) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz> * * The __delay function must _NOT_ be inlined as its execution time * depends wildly on alignment on many x86 processors. The additional * jump magic is needed to get the timing stable on all the CPU's * we have to worry about. */ #include <linux/sched.h> #include <linux/delay.h> #ifdef __SMP__ #include <asm/smp.h> #endif void __delay(unsigned long loops) { __asm__ __volatile__( "\tjmp 1f\n" ".align 16\n" "1:\tjmp 2f\n" ".align 16\n" "2:\tdecl %0\n\tjns 2b" :/* no outputs */ :"a" (loops) :"ax"); } inline void __const_udelay(unsigned long xloops) { __asm__("mull %0" :"=d" (xloops) :"a" (xloops),"0" (current_cpu_data.loops_per_sec) :"ax"); __delay(xloops); } void __udelay(unsigned long usecs) { __const_udelay(usecs * 0x000010c6); /* 2**32 / 1000000 */ } |