1da177e4c3
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
142 lines
3.4 KiB
C
142 lines
3.4 KiB
C
#include <linux/bitops.h>
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#undef find_first_zero_bit
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#undef find_next_zero_bit
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#undef find_first_bit
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#undef find_next_bit
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/**
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* find_first_zero_bit - find the first zero bit in a memory region
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* @addr: The address to start the search at
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* @size: The maximum size to search
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*
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* Returns the bit-number of the first zero bit, not the number of the byte
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* containing a bit.
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*/
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inline long find_first_zero_bit(const unsigned long * addr, unsigned long size)
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{
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long d0, d1, d2;
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long res;
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if (!size)
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return 0;
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asm volatile(
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" repe; scasq\n"
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" je 1f\n"
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" xorq -8(%%rdi),%%rax\n"
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" subq $8,%%rdi\n"
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" bsfq %%rax,%%rdx\n"
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"1: subq %[addr],%%rdi\n"
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" shlq $3,%%rdi\n"
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" addq %%rdi,%%rdx"
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:"=d" (res), "=&c" (d0), "=&D" (d1), "=&a" (d2)
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:"0" (0ULL), "1" ((size + 63) >> 6), "2" (addr), "3" (-1ULL),
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[addr] "r" (addr) : "memory");
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return res;
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}
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/**
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* find_next_zero_bit - find the first zero bit in a memory region
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* @addr: The address to base the search on
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* @offset: The bitnumber to start searching at
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* @size: The maximum size to search
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*/
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long find_next_zero_bit (const unsigned long * addr, long size, long offset)
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{
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unsigned long * p = ((unsigned long *) addr) + (offset >> 6);
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unsigned long set = 0;
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unsigned long res, bit = offset&63;
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if (bit) {
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/*
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* Look for zero in first word
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*/
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asm("bsfq %1,%0\n\t"
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"cmoveq %2,%0"
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: "=r" (set)
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: "r" (~(*p >> bit)), "r"(64L));
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if (set < (64 - bit))
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return set + offset;
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set = 64 - bit;
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p++;
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}
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/*
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* No zero yet, search remaining full words for a zero
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*/
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res = find_first_zero_bit ((const unsigned long *)p,
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size - 64 * (p - (unsigned long *) addr));
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return (offset + set + res);
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}
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static inline long
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__find_first_bit(const unsigned long * addr, unsigned long size)
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{
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long d0, d1;
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long res;
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asm volatile(
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" repe; scasq\n"
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" jz 1f\n"
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" subq $8,%%rdi\n"
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" bsfq (%%rdi),%%rax\n"
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"1: subq %[addr],%%rdi\n"
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" shlq $3,%%rdi\n"
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" addq %%rdi,%%rax"
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:"=a" (res), "=&c" (d0), "=&D" (d1)
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:"0" (0ULL),
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"1" ((size + 63) >> 6), "2" (addr),
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[addr] "r" (addr) : "memory");
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return res;
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}
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/**
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* find_first_bit - find the first set bit in a memory region
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* @addr: The address to start the search at
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* @size: The maximum size to search
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*
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* Returns the bit-number of the first set bit, not the number of the byte
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* containing a bit.
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*/
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long find_first_bit(const unsigned long * addr, unsigned long size)
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{
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return __find_first_bit(addr,size);
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}
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/**
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* find_next_bit - find the first set bit in a memory region
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* @addr: The address to base the search on
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* @offset: The bitnumber to start searching at
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* @size: The maximum size to search
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*/
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long find_next_bit(const unsigned long * addr, long size, long offset)
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{
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const unsigned long * p = addr + (offset >> 6);
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unsigned long set = 0, bit = offset & 63, res;
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if (bit) {
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/*
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* Look for nonzero in the first 64 bits:
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*/
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asm("bsfq %1,%0\n\t"
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"cmoveq %2,%0\n\t"
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: "=r" (set)
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: "r" (*p >> bit), "r" (64L));
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if (set < (64 - bit))
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return set + offset;
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set = 64 - bit;
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p++;
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}
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/*
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* No set bit yet, search remaining full words for a bit
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*/
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res = __find_first_bit (p, size - 64 * (p - addr));
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return (offset + set + res);
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}
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#include <linux/module.h>
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EXPORT_SYMBOL(find_next_bit);
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EXPORT_SYMBOL(find_first_bit);
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EXPORT_SYMBOL(find_first_zero_bit);
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EXPORT_SYMBOL(find_next_zero_bit);
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