256 lines
6.2 KiB
C
256 lines
6.2 KiB
C
/* $FreeBSD$ */
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#ifndef _ALPHA_BITOPS_H
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#define _ALPHA_BITOPS_H
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/*
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* Copyright 1994, 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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* To get proper branch prediction for the main line, we must branch
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* forward to code at the end of this object's .text section, then
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* branch back to restart the operation.
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*
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* bit 0 is the LSB of addr; bit 64 is the LSB of (addr+1).
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*/
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static __inline unsigned int set_bit(unsigned long, volatile void *);
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static __inline unsigned int clear_bit(unsigned long, volatile void *);
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static __inline unsigned int change_bit(unsigned long, volatile void *);
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static __inline unsigned int test_bit(int, volatile void *);
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static __inline unsigned long ffz_b(unsigned long x);
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static __inline unsigned long ffz(unsigned long);
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/* static __inline int ffs(int); */
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static __inline void * memscan(void *, int, size_t);
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#ifdef __alpha_cix__
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static __inline unsigned long hweight64(unsigned long);
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#endif
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static __inline unsigned long
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find_next_zero_bit(void *, unsigned long, unsigned long);
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static __inline unsigned int set_bit(unsigned long nr, volatile void * addr)
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{
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unsigned long oldbit;
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unsigned long temp;
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volatile unsigned int *m = ((volatile unsigned int *) addr) + (nr >> 5);
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__asm__ __volatile__(
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"1: ldl_l %0,%1\n"
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" and %0,%3,%2\n"
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" bne %2,2f\n"
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" xor %0,%3,%0\n"
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" stl_c %0,%1\n"
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" beq %0,3f\n"
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"2:\n"
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".section .text2,\"ax\"\n"
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"3: br 1b\n"
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".previous"
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:"=&r" (temp), "=m" (*m), "=&r" (oldbit)
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:"Ir" (1UL << (nr & 31)), "m" (*m));
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return oldbit;
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}
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static __inline unsigned int clear_bit(unsigned long nr, volatile void * addr)
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{
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unsigned long oldbit;
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unsigned long temp;
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volatile unsigned int *m = ((volatile unsigned int *) addr) + (nr >> 5);
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__asm__ __volatile__(
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"1: ldl_l %0,%1\n"
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" and %0,%3,%2\n"
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" beq %2,2f\n"
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" xor %0,%3,%0\n"
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" stl_c %0,%1\n"
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" beq %0,3f\n"
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"2:\n"
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".section .text2,\"ax\"\n"
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"3: br 1b\n"
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".previous"
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:"=&r" (temp), "=m" (*m), "=&r" (oldbit)
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:"Ir" (1UL << (nr & 31)), "m" (*m));
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return oldbit;
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}
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static __inline unsigned int change_bit(unsigned long nr, volatile void * addr)
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{
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unsigned long oldbit;
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unsigned long temp;
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volatile unsigned int *m = ((volatile unsigned int *) addr) + (nr >> 5);
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__asm__ __volatile__(
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"1: ldl_l %0,%1\n"
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" xor %0,%2,%0\n"
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" stl_c %0,%1\n"
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" beq %0,3f\n"
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".section .text2,\"ax\"\n"
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"3: br 1b\n"
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".previous"
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:"=&r" (temp), "=m" (*m), "=&r" (oldbit)
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:"Ir" (1UL << (nr & 31)), "m" (*m));
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return oldbit;
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}
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static __inline unsigned int test_bit(int nr, volatile void * addr)
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{
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return 1UL & (((volatile int *) addr)[nr >> 5] >> (nr & 31));
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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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* Do a binary search on the bits. Due to the nature of large
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* constants on the alpha, it is worthwhile to split the search.
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*/
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static __inline unsigned long ffz_b(unsigned long x)
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{
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unsigned long sum = 0;
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x = ~x & -~x; /* set first 0 bit, clear others */
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if (x & 0xF0) sum += 4;
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if (x & 0xCC) sum += 2;
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if (x & 0xAA) sum += 1;
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return sum;
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}
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static __inline unsigned long ffz(unsigned long word)
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{
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#ifdef __alpha_cix__
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/* Whee. EV6 can calculate it directly. */
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unsigned long result;
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__asm__("ctlz %1,%0" : "=r"(result) : "r"(~word));
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return result;
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#else
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unsigned long bits, qofs, bofs;
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__asm__("cmpbge %1,%2,%0" : "=r"(bits) : "r"(word), "r"(~0UL));
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qofs = ffz_b(bits);
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__asm__("extbl %1,%2,%0" : "=r"(bits) : "r"(word), "r"(qofs));
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bofs = ffz_b(bits);
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return qofs*8 + bofs;
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#endif
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}
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#ifdef __KERNEL__
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#if 0
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/*
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* ffs: find first bit set. This is defined the same way as
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* the libc and compiler builtin ffs routines, therefore
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* differs in spirit from the above ffz (man ffs).
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*/
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static __inline int ffs(int word)
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{
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int result = ffz(~word);
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return word ? result+1 : 0;
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}
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#endif
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/*
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* hweightN: returns the hamming weight (i.e. the number
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* of bits set) of a N-bit word
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*/
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#ifdef __alpha_cix__
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/* Whee. EV6 can calculate it directly. */
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static __inline unsigned long hweight64(unsigned long w)
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{
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unsigned long result;
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__asm__("ctpop %1,%0" : "=r"(result) : "r"(w));
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return result;
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}
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#define hweight32(x) hweight64((x) & 0xfffffffful)
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#define hweight16(x) hweight64((x) & 0xfffful)
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#define hweight8(x) hweight64((x) & 0xfful)
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#else
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#define hweight32(x) generic_hweight32(x)
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#define hweight16(x) generic_hweight16(x)
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#define hweight8(x) generic_hweight8(x)
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#endif
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#endif /* __alpha_cix__ */
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/* from lib/string.c */
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static __inline void * memscan(void * addr, int c, size_t size)
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{
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unsigned char * p = (unsigned char *) addr;
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while (size) {
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if (*p == c)
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return (void *) p;
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p++;
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size--;
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}
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return (void *) p;
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}
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/*
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* Find next zero bit in a bitmap reasonably efficiently..
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*/
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static __inline unsigned long find_next_zero_bit(void * addr, unsigned long size, unsigned long offset)
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{
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unsigned long * p = ((unsigned long *) addr) + (offset >> 6);
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unsigned long result = offset & ~63UL;
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unsigned long tmp;
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if (offset >= size)
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return size;
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size -= result;
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offset &= 63UL;
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if (offset) {
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tmp = *(p++);
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tmp |= ~0UL >> (64-offset);
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if (size < 64)
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goto found_first;
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if (~tmp)
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goto found_middle;
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size -= 64;
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result += 64;
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}
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while (size & ~63UL) {
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if (~(tmp = *(p++)))
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goto found_middle;
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result += 64;
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size -= 64;
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}
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if (!size)
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return result;
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tmp = *p;
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found_first:
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tmp |= ~0UL << size;
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found_middle:
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return result + ffz(tmp);
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}
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/*
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* The optimizer actually does good code for this case..
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*/
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#define find_first_zero_bit(addr, size) \
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find_next_zero_bit((addr), (size), 0)
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#ifdef __KERNEL__
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#define ext2_set_bit test_and_set_bit
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#define ext2_clear_bit test_and_clear_bit
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#define ext2_test_bit test_bit
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#define ext2_find_first_zero_bit find_first_zero_bit
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#define ext2_find_next_zero_bit find_next_zero_bit
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/* Bitmap functions for the minix filesystem. */
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#define minix_set_bit(nr,addr) test_and_set_bit(nr,addr)
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#define minix_clear_bit(nr,addr) test_and_clear_bit(nr,addr)
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#define minix_test_bit(nr,addr) test_bit(nr,addr)
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#define minix_find_first_zero_bit(addr,size) find_first_zero_bit(addr,size)
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#endif /* __KERNEL__ */
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#endif /* _ALPHA_BITOPS_H */
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