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Diffstat (limited to 'include/asm-i386/delay.h')
-rw-r--r-- | include/asm-i386/delay.h | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/include/asm-i386/delay.h b/include/asm-i386/delay.h new file mode 100644 index 000000000..7ff5f769c --- /dev/null +++ b/include/asm-i386/delay.h @@ -0,0 +1,35 @@ +#ifndef _I386_DELAY_H +#define _I386_DELAY_H + +/* + * Copyright (C) 1993 Linus Torvalds + * + * Delay routines, using a pre-computed "loops_per_second" value. + */ + +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 /* defined(_I386_DELAY_H) */ |