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[/] [or1k/] [trunk/] [uclinux/] [uClinux-2.0.x/] [include/] [asm-alpha/] [bitops.h] - Blame information for rev 1765

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1 199 simons
#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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 * bit 0 is the LSB of addr; bit 64 is the LSB of (addr+1).
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 */
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extern __inline__ unsigned long set_bit(unsigned long nr, void * addr)
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{
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        unsigned long oldbit;
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        unsigned long temp;
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        unsigned int * m = ((unsigned int *) addr) + (nr >> 5);
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        __asm__ __volatile__(
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                "\n1:\t"
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                "ldl_l %0,%1\n\t"
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                "and %0,%3,%2\n\t"
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                "bne %2,2f\n\t"
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                "xor %0,%3,%0\n\t"
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                "stl_c %0,%1\n\t"
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                "beq %0,1b\n"
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                "2:"
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                :"=&r" (temp),
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                 "=m" (*m),
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                 "=&r" (oldbit)
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                :"Ir" (1UL << (nr & 31)),
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                 "m" (*m));
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        return oldbit != 0;
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}
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extern __inline__ unsigned long clear_bit(unsigned long nr, void * addr)
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{
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        unsigned long oldbit;
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        unsigned long temp;
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        unsigned int * m = ((unsigned int *) addr) + (nr >> 5);
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        __asm__ __volatile__(
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                "\n1:\t"
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                "ldl_l %0,%1\n\t"
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                "and %0,%3,%2\n\t"
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                "beq %2,2f\n\t"
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                "xor %0,%3,%0\n\t"
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                "stl_c %0,%1\n\t"
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                "beq %0,1b\n"
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                "2:"
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                :"=&r" (temp),
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                 "=m" (*m),
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                 "=&r" (oldbit)
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                :"Ir" (1UL << (nr & 31)),
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                 "m" (*m));
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        return oldbit != 0;
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}
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extern __inline__ unsigned long change_bit(unsigned long nr, void * addr)
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{
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        unsigned long oldbit;
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        unsigned long temp;
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        unsigned int * m = ((unsigned int *) addr) + (nr >> 5);
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        __asm__ __volatile__(
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                "\n1:\t"
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                "ldl_l %0,%1\n\t"
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                "and %0,%3,%2\n\t"
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                "xor %0,%3,%0\n\t"
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                "stl_c %0,%1\n\t"
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                "beq %0,1b\n"
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                :"=&r" (temp),
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                 "=m" (*m),
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                 "=&r" (oldbit)
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                :"Ir" (1UL << (nr & 31)),
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                 "m" (*m));
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        return oldbit != 0;
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}
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extern __inline__ unsigned long test_bit(int nr, const void * addr)
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{
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        return 1UL & (((const 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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extern 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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extern inline unsigned long ffz(unsigned long word)
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{
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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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}
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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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extern 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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#endif /* _ALPHA_BITOPS_H */

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