435286fb59
contaminated with the GPL code. While this information was present in the COPYRIGHT.INFO file, it is FreeBSD's standard practice to, where possible, include explicit license information in files. Approved by: release engineer (scottl)
176 lines
4.1 KiB
C
176 lines
4.1 KiB
C
/* $FreeBSD$ */
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/*
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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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/*-
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* Copyright 1992, Linus Torvalds.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*
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*/
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#ifndef _SYS_GNU_EXT2FS_I386_BITOPS_H_
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#define _SYS_GNU_EXT2FS_I386_BITOPS_H_
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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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static __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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static __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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static __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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static __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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static __inline__ int find_first_zero_bit(void * addr, unsigned size)
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{
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int res;
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int _count = (size + 31) >> 5;
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if (!size)
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return 0;
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__asm__(" \n\
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cld \n\
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movl $-1,%%eax \n\
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xorl %%edx,%%edx \n\
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repe; scasl \n\
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je 1f \n\
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xorl -4(%%edi),%%eax \n\
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subl $4,%%edi \n\
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bsfl %%eax,%%edx \n\
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1: subl %%ebx,%%edi \n\
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shll $3,%%edi \n\
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addl %%edi,%%edx"
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: "=c" (_count), "=D" (addr), "=d" (res)
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: "0" (_count), "1" (addr), "b" (addr)
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: "ax");
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return res;
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}
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static __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__(" \n\
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bsfl %1,%0 \n\
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jne 1f \n\
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movl $32, %0 \n\
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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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static __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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static __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__(" \n\
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cld \n\
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repnz; scasb \n\
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jnz 1f \n\
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dec %%edi \n\
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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 /* !_SYS_GNU_EXT2FS_I386_BITOPS_H_ */
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