bitmap.c revision 234370
1234370Sjasone#define JEMALLOC_BITMAP_C_ 2234370Sjasone#include "jemalloc/internal/jemalloc_internal.h" 3234370Sjasone 4234370Sjasone/******************************************************************************/ 5234370Sjasone/* Function prototypes for non-inline static functions. */ 6234370Sjasone 7234370Sjasonestatic size_t bits2groups(size_t nbits); 8234370Sjasone 9234370Sjasone/******************************************************************************/ 10234370Sjasone 11234370Sjasonestatic size_t 12234370Sjasonebits2groups(size_t nbits) 13234370Sjasone{ 14234370Sjasone 15234370Sjasone return ((nbits >> LG_BITMAP_GROUP_NBITS) + 16234370Sjasone !!(nbits & BITMAP_GROUP_NBITS_MASK)); 17234370Sjasone} 18234370Sjasone 19234370Sjasonevoid 20234370Sjasonebitmap_info_init(bitmap_info_t *binfo, size_t nbits) 21234370Sjasone{ 22234370Sjasone unsigned i; 23234370Sjasone size_t group_count; 24234370Sjasone 25234370Sjasone assert(nbits > 0); 26234370Sjasone assert(nbits <= (ZU(1) << LG_BITMAP_MAXBITS)); 27234370Sjasone 28234370Sjasone /* 29234370Sjasone * Compute the number of groups necessary to store nbits bits, and 30234370Sjasone * progressively work upward through the levels until reaching a level 31234370Sjasone * that requires only one group. 32234370Sjasone */ 33234370Sjasone binfo->levels[0].group_offset = 0; 34234370Sjasone group_count = bits2groups(nbits); 35234370Sjasone for (i = 1; group_count > 1; i++) { 36234370Sjasone assert(i < BITMAP_MAX_LEVELS); 37234370Sjasone binfo->levels[i].group_offset = binfo->levels[i-1].group_offset 38234370Sjasone + group_count; 39234370Sjasone group_count = bits2groups(group_count); 40234370Sjasone } 41234370Sjasone binfo->levels[i].group_offset = binfo->levels[i-1].group_offset 42234370Sjasone + group_count; 43234370Sjasone binfo->nlevels = i; 44234370Sjasone binfo->nbits = nbits; 45234370Sjasone} 46234370Sjasone 47234370Sjasonesize_t 48234370Sjasonebitmap_info_ngroups(const bitmap_info_t *binfo) 49234370Sjasone{ 50234370Sjasone 51234370Sjasone return (binfo->levels[binfo->nlevels].group_offset << LG_SIZEOF_BITMAP); 52234370Sjasone} 53234370Sjasone 54234370Sjasonesize_t 55234370Sjasonebitmap_size(size_t nbits) 56234370Sjasone{ 57234370Sjasone bitmap_info_t binfo; 58234370Sjasone 59234370Sjasone bitmap_info_init(&binfo, nbits); 60234370Sjasone return (bitmap_info_ngroups(&binfo)); 61234370Sjasone} 62234370Sjasone 63234370Sjasonevoid 64234370Sjasonebitmap_init(bitmap_t *bitmap, const bitmap_info_t *binfo) 65234370Sjasone{ 66234370Sjasone size_t extra; 67234370Sjasone unsigned i; 68234370Sjasone 69234370Sjasone /* 70234370Sjasone * Bits are actually inverted with regard to the external bitmap 71234370Sjasone * interface, so the bitmap starts out with all 1 bits, except for 72234370Sjasone * trailing unused bits (if any). Note that each group uses bit 0 to 73234370Sjasone * correspond to the first logical bit in the group, so extra bits 74234370Sjasone * are the most significant bits of the last group. 75234370Sjasone */ 76234370Sjasone memset(bitmap, 0xffU, binfo->levels[binfo->nlevels].group_offset << 77234370Sjasone LG_SIZEOF_BITMAP); 78234370Sjasone extra = (BITMAP_GROUP_NBITS - (binfo->nbits & BITMAP_GROUP_NBITS_MASK)) 79234370Sjasone & BITMAP_GROUP_NBITS_MASK; 80234370Sjasone if (extra != 0) 81234370Sjasone bitmap[binfo->levels[1].group_offset - 1] >>= extra; 82234370Sjasone for (i = 1; i < binfo->nlevels; i++) { 83234370Sjasone size_t group_count = binfo->levels[i].group_offset - 84234370Sjasone binfo->levels[i-1].group_offset; 85234370Sjasone extra = (BITMAP_GROUP_NBITS - (group_count & 86234370Sjasone BITMAP_GROUP_NBITS_MASK)) & BITMAP_GROUP_NBITS_MASK; 87234370Sjasone if (extra != 0) 88234370Sjasone bitmap[binfo->levels[i+1].group_offset - 1] >>= extra; 89234370Sjasone } 90234370Sjasone} 91