c33a4405f7
file for GPL restrictions. This code was ported to the BSD platform by Godmar Back <gback@facility.cs.utah.edu> and specifically to FreeBSD by John Dyson. This code is still green and should be used with caution. Additional changes to UFS necessary to make this code work will be commited seperately. Submitted by: Godmar Back <gback@facility.cs.utah.edu> Obtained from: Lites/Mach4
160 lines
3.1 KiB
C
160 lines
3.1 KiB
C
/*
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* this is mixture of i386/bitops.h and asm/string.h
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* taken from the Linux source tree
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*
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* XXX replace with Mach routines or reprogram in C
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*/
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#ifndef _I386_BITOPS_H
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#define _I386_BITOPS_H
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/*
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* Copyright 1992, Linus Torvalds.
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*/
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/*
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* These have to be done with inline assembly: that way the bit-setting
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* is guaranteed to be atomic. All bit operations return 0 if the bit
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* was cleared before the operation and != 0 if it was not.
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*
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* bit 0 is the LSB of addr; bit 32 is the LSB of (addr+1).
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*/
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/*
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* Some hacks to defeat gcc over-optimizations..
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*/
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struct __dummy { unsigned long a[100]; };
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#define ADDR (*(struct __dummy *) addr)
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extern __inline__ int set_bit(int nr, void * addr)
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{
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int oldbit;
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__asm__ __volatile__("btsl %2,%1\n\tsbbl %0,%0"
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:"=r" (oldbit),"=m" (ADDR)
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:"ir" (nr));
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return oldbit;
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}
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extern __inline__ int clear_bit(int nr, void * addr)
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{
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int oldbit;
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__asm__ __volatile__("btrl %2,%1\n\tsbbl %0,%0"
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:"=r" (oldbit),"=m" (ADDR)
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:"ir" (nr));
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return oldbit;
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}
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extern __inline__ int change_bit(int nr, void * addr)
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{
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int oldbit;
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__asm__ __volatile__("btcl %2,%1\n\tsbbl %0,%0"
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:"=r" (oldbit),"=m" (ADDR)
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:"ir" (nr));
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return oldbit;
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}
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/*
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* This routine doesn't need to be atomic, but it's faster to code it
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* this way.
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*/
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extern __inline__ int test_bit(int nr, void * addr)
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{
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int oldbit;
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__asm__ __volatile__("btl %2,%1\n\tsbbl %0,%0"
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:"=r" (oldbit)
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:"m" (ADDR),"ir" (nr));
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return oldbit;
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}
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/*
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* Find-bit routines..
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*/
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extern inline int find_first_zero_bit(void * addr, unsigned size)
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{
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int res;
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if (!size)
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return 0;
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__asm__("
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cld
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movl $-1,%%eax
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xorl %%edx,%%edx
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repe; scasl
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je 1f
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xorl -4(%%edi),%%eax
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subl $4,%%edi
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bsfl %%eax,%%edx
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1: subl %%ebx,%%edi
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shll $3,%%edi
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addl %%edi,%%edx"
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:"=d" (res)
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:"c" ((size + 31) >> 5), "D" (addr), "b" (addr)
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:"ax", "cx", "di");
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return res;
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}
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extern inline int find_next_zero_bit (void * addr, int size, int offset)
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{
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unsigned long * p = ((unsigned long *) addr) + (offset >> 5);
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int set = 0, bit = offset & 31, res;
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if (bit) {
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/*
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* Look for zero in first byte
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*/
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__asm__("
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bsfl %1,%0
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jne 1f
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movl $32, %0
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1: "
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: "=r" (set)
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: "r" (~(*p >> bit)));
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if (set < (32 - bit))
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return set + offset;
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set = 32 - bit;
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p++;
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}
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/*
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* No zero yet, search remaining full bytes for a zero
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*/
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res = find_first_zero_bit (p, size - 32 * (p - (unsigned long *) addr));
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return (offset + set + res);
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}
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/*
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* ffz = Find First Zero in word. Undefined if no zero exists,
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* so code should check against ~0UL first..
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*/
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extern inline unsigned long ffz(unsigned long word)
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{
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__asm__("bsfl %1,%0"
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:"=r" (word)
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:"r" (~word));
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return word;
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}
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/*
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* memscan() taken from linux asm/string.h
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*/
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/*
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* find the first occurrence of byte 'c', or 1 past the area if none
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*/
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extern inline char * memscan(void * addr, unsigned char c, int size)
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{
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if (!size)
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return addr;
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__asm__("cld
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repnz; scasb
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jnz 1f
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dec %%edi
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1: "
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: "=D" (addr), "=c" (size)
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: "0" (addr), "1" (size), "a" (c));
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return addr;
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}
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#endif /* _I386_BITOPS_H */
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