91 lines
2.5 KiB
C
91 lines
2.5 KiB
C
#define JEMALLOC_BITMAP_C_
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#include "jemalloc/internal/jemalloc_internal.h"
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/******************************************************************************/
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/* Function prototypes for non-inline static functions. */
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static size_t bits2groups(size_t nbits);
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/******************************************************************************/
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static size_t
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bits2groups(size_t nbits)
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{
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return ((nbits >> LG_BITMAP_GROUP_NBITS) +
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!!(nbits & BITMAP_GROUP_NBITS_MASK));
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}
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void
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bitmap_info_init(bitmap_info_t *binfo, size_t nbits)
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{
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unsigned i;
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size_t group_count;
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assert(nbits > 0);
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assert(nbits <= (ZU(1) << LG_BITMAP_MAXBITS));
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/*
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* Compute the number of groups necessary to store nbits bits, and
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* progressively work upward through the levels until reaching a level
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* that requires only one group.
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*/
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binfo->levels[0].group_offset = 0;
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group_count = bits2groups(nbits);
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for (i = 1; group_count > 1; i++) {
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assert(i < BITMAP_MAX_LEVELS);
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binfo->levels[i].group_offset = binfo->levels[i-1].group_offset
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+ group_count;
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group_count = bits2groups(group_count);
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}
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binfo->levels[i].group_offset = binfo->levels[i-1].group_offset
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+ group_count;
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binfo->nlevels = i;
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binfo->nbits = nbits;
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}
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size_t
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bitmap_info_ngroups(const bitmap_info_t *binfo)
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{
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return (binfo->levels[binfo->nlevels].group_offset << LG_SIZEOF_BITMAP);
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}
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size_t
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bitmap_size(size_t nbits)
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{
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bitmap_info_t binfo;
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bitmap_info_init(&binfo, nbits);
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return (bitmap_info_ngroups(&binfo));
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}
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void
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bitmap_init(bitmap_t *bitmap, const bitmap_info_t *binfo)
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{
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size_t extra;
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unsigned i;
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/*
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* Bits are actually inverted with regard to the external bitmap
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* interface, so the bitmap starts out with all 1 bits, except for
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* trailing unused bits (if any). Note that each group uses bit 0 to
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* correspond to the first logical bit in the group, so extra bits
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* are the most significant bits of the last group.
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*/
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memset(bitmap, 0xffU, binfo->levels[binfo->nlevels].group_offset <<
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LG_SIZEOF_BITMAP);
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extra = (BITMAP_GROUP_NBITS - (binfo->nbits & BITMAP_GROUP_NBITS_MASK))
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& BITMAP_GROUP_NBITS_MASK;
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if (extra != 0)
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bitmap[binfo->levels[1].group_offset - 1] >>= extra;
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for (i = 1; i < binfo->nlevels; i++) {
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size_t group_count = binfo->levels[i].group_offset -
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binfo->levels[i-1].group_offset;
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extra = (BITMAP_GROUP_NBITS - (group_count &
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BITMAP_GROUP_NBITS_MASK)) & BITMAP_GROUP_NBITS_MASK;
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if (extra != 0)
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bitmap[binfo->levels[i+1].group_offset - 1] >>= extra;
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}
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}
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