diff options
Diffstat (limited to 'elf/dl-hwcaps.h')
| -rw-r--r-- | elf/dl-hwcaps.h | 105 |
1 files changed, 105 insertions, 0 deletions
diff --git a/elf/dl-hwcaps.h b/elf/dl-hwcaps.h index b66da59..ab39d8a 100644 --- a/elf/dl-hwcaps.h +++ b/elf/dl-hwcaps.h @@ -16,6 +16,11 @@ License along with the GNU C Library; if not, see <https://www.gnu.org/licenses/>. */ +#ifndef _DL_HWCAPS_H +#define _DL_HWCAPS_H + +#include <stdint.h> + #include <elf/dl-tunables.h> #if HAVE_TUNABLES @@ -28,3 +33,103 @@ # define GET_HWCAP_MASK() (0) # endif #endif + +#define GLIBC_HWCAPS_SUBDIRECTORY "glibc-hwcaps" +#define GLIBC_HWCAPS_PREFIX GLIBC_HWCAPS_SUBDIRECTORY "/" + +/* Used by _dl_hwcaps_split below, to split strings at ':' + separators. */ +struct dl_hwcaps_split +{ + const char *segment; /* Start of the current segment. */ + size_t length; /* Number of bytes until ':' or NUL. */ +}; + +/* Prepare *S to parse SUBJECT, for future _dl_hwcaps_split calls. If + SUBJECT is NULL, it is treated as the empty string. */ +static inline void +_dl_hwcaps_split_init (struct dl_hwcaps_split *s, const char *subject) +{ + s->segment = subject; + /* The initial call to _dl_hwcaps_split will not skip anything. */ + s->length = 0; +} + +/* Extract the next non-empty string segment, up to ':' or the null + terminator. Return true if one more segment was found, or false if + the end of the string was reached. On success, S->segment is the + start of the segment found, and S->length is its length. + (Typically, S->segment[S->length] is not null.) */ +_Bool _dl_hwcaps_split (struct dl_hwcaps_split *s) attribute_hidden; + +/* Similar to dl_hwcaps_split, but with bit-based and name-based + masking. */ +struct dl_hwcaps_split_masked +{ + struct dl_hwcaps_split split; + + /* For used by the iterator implementation. */ + const char *mask; + uint32_t bitmask; +}; + +/* Prepare *S for iteration with _dl_hwcaps_split_masked. Only HWCAP + names in SUBJECT whose bit is set in BITMASK and whose name is in + MASK will be returned. SUBJECT must not contain empty HWCAP names. + If MASK is NULL, no name-based masking is applied. Likewise for + BITMASK if BITMASK is -1 (infinite number of bits). */ +static inline void +_dl_hwcaps_split_masked_init (struct dl_hwcaps_split_masked *s, + const char *subject, + uint32_t bitmask, const char *mask) +{ + _dl_hwcaps_split_init (&s->split, subject); + s->bitmask = bitmask; + s->mask = mask; +} + +/* Like _dl_hwcaps_split, but apply masking. */ +_Bool _dl_hwcaps_split_masked (struct dl_hwcaps_split_masked *s) + attribute_hidden; + +/* Returns true if the colon-separated HWCAP list HWCAPS contains the + capability NAME (with length NAME_LENGTH). If HWCAPS is NULL, the + function returns true. */ +_Bool _dl_hwcaps_contains (const char *hwcaps, const char *name, + size_t name_length) attribute_hidden; + +/* Colon-separated string of glibc-hwcaps subdirectories, without the + "glibc-hwcaps/" prefix. The most preferred subdirectory needs to + be listed first. Up to 32 subdirectories are supported, limited by + the width of the uint32_t mask. */ +extern const char _dl_hwcaps_subdirs[] attribute_hidden; + +/* Returns a bitmap of active subdirectories in _dl_hwcaps_subdirs. + Bit 0 (the LSB) corresponds to the first substring in + _dl_hwcaps_subdirs, bit 1 to the second substring, and so on. + There is no direct correspondence between HWCAP bitmasks and this + bitmask. */ +uint32_t _dl_hwcaps_subdirs_active (void) attribute_hidden; + +/* Returns a bitmask that marks the last ACTIVE subdirectories in a + _dl_hwcaps_subdirs_active string (containing SUBDIRS directories in + total) as active. Intended for use in _dl_hwcaps_subdirs_active + implementations (if a contiguous tail of the list in + _dl_hwcaps_subdirs is selected). */ +static inline uint32_t +_dl_hwcaps_subdirs_build_bitmask (int subdirs, int active) +{ + /* Leading subdirectories that are not active. */ + int inactive = subdirs - active; + if (inactive == 32) + return 0; + + uint32_t mask; + if (subdirs != 32) + mask = (1U << subdirs) - 1; + else + mask = -1; + return mask ^ ((1U << inactive) - 1); +} + +#endif /* _DL_HWCAPS_H */ |