diff options
Diffstat (limited to 'zahl.h')
| -rw-r--r-- | zahl.h | 65 |
1 files changed, 63 insertions, 2 deletions
@@ -98,8 +98,6 @@ void zrsh(z_t, z_t, size_t); /* a := b >> c */ void ztrunc(z_t, z_t, size_t); /* a := b & ((1 << c) - 1) */ int zbtest(z_t, size_t); /* (a >> b) & 1 */ void zsplit(z_t, z_t, z_t, size_t); /* a := c >> d, b := c - (a << d) */ -size_t zbits(z_t); /* ⌊log₂ |a|⌋ + 1, 1 if a = 0 */ -size_t zlsb(z_t); /* Index of first set bit, SIZE_MAX if none are set. */ /* If d > 0: a := b | (1 << c), f d = 0: a := b & ~(1 << c), if d < 0: a := b ^ (1 << c) */ void zbset(z_t, z_t, size_t, int); @@ -147,3 +145,66 @@ static inline int zzero(z_t a) { return !a->sign; } static inline int zsignum(z_t a) { return a->sign; } /* a/|a|, 0 if a is zero. */ static inline void zabs(z_t a, z_t b) { if (a != b) zset(a, b); a->sign = !!a->sign; } /* a := |b| */ static inline void zneg(z_t a, z_t b) { if (a != b) zset(a, b); a->sign = -a->sign; } /* a := -b */ + + +/* Bitwise inline functions. */ + + +/* Index of first set bit, SIZE_MAX if none are set. */ +#if defined(__GNUC__) || defined(__clang__) +static inline size_t +zlsb(z_t a) +{ + size_t i = 0; + if (__builtin_expect(zzero(a), 0)) + return SIZE_MAX; + for (; !a->chars[i]; i++); + i *= 8 * sizeof(zahl_char_t); + i += __builtin_ctzll(a->chars[i]); + return i; +} +#else +static inline size_t +zlsb(z_t a) +{ + size_t i = 0; + zahl_char_t x; + if (zzero(a)) + return SIZE_MAX; + for (; !a->chars[i]; i++); + i *= 8 * sizeof(zahl_char_t); + x = ~(a->chars[i]); + for (; x & 1; x >>= 1, i++); + return i; +} +#endif + + +/* ⌊log₂ |a|⌋ + 1, 1 if a = 0 */ +#if defined(__GNUC__) || defined(__clang__) +static inline size_t +zbits(z_t a) +{ + size_t rc; + if (__builtin_expect(zzero(a), 0)) + return 1; + while (!a->chars[a->used - 1]) a->used--; /* TODO should not be necessary */ + rc = a->used * 8 * sizeof(zahl_char_t); + rc -= __builtin_clzll(a->chars[a->used - 1]); + return rc; +} +#else +static inline size_t +zbits(z_t a) +{ + size_t rc; + zahl_char_t x; + if (zzero(a)) + return 1; + while (!a->chars[a->used - 1]) a->used--; /* TODO should not be necessary */ + x = a->chars[a->used - 1]; + rc = (a->used - 1) * 8 * sizeof(zahl_char_t); + for (; x; x >>= 1, rc++); + return rc; +} +#endif |