diff options
| -rw-r--r-- | sysdeps/generic/string-fza.h | 98 | ||||
| -rw-r--r-- | sysdeps/generic/string-fzb.h | 49 | ||||
| -rw-r--r-- | sysdeps/generic/string-fzc.h | 87 | ||||
| -rw-r--r-- | sysdeps/generic/string-fzi.h | 71 | ||||
| -rw-r--r-- | sysdeps/generic/string-misc.h | 45 | ||||
| -rw-r--r-- | sysdeps/generic/string-shift.h | 52 |
6 files changed, 402 insertions, 0 deletions
diff --git a/sysdeps/generic/string-fza.h b/sysdeps/generic/string-fza.h new file mode 100644 index 0000000..69ee04d --- /dev/null +++ b/sysdeps/generic/string-fza.h @@ -0,0 +1,98 @@ +/* Basic zero byte detection. Generic C version. + Copyright (C) 2023 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <http://www.gnu.org/licenses/>. */ + +#ifndef _STRING_FZA_H +#define _STRING_FZA_H 1 + +#include <string-misc.h> +#include <string-optype.h> + +/* The function return a byte mask. */ +typedef op_t find_t; + +/* This function returns non-zero if any byte in X is zero. + More specifically, at least one bit set within the least significant + byte that was zero; other bytes within the word are indeterminate. */ +static __always_inline find_t +find_zero_low (op_t x) +{ + /* This expression comes from + https://graphics.stanford.edu/~seander/bithacks.html#ZeroInWord + Subtracting 1 sets 0x80 in a byte that was 0; anding ~x clears + 0x80 in a byte that was >= 128; anding 0x80 isolates that test bit. */ + op_t lsb = repeat_bytes (0x01); + op_t msb = repeat_bytes (0x80); + return (x - lsb) & ~x & msb; +} + +/* This function returns at least one bit set within every byte of X that + is zero. The result is exact in that, unlike find_zero_low, all bytes + are determinate. This is usually used for finding the index of the + most significant byte that was zero. */ +static __always_inline find_t +find_zero_all (op_t x) +{ + /* For each byte, find not-zero by + (0) And 0x7f so that we cannot carry between bytes, + (1) Add 0x7f so that non-zero carries into 0x80, + (2) Or in the original byte (which might have had 0x80 set). + Then invert and mask such that 0x80 is set iff that byte was zero. */ + op_t m = repeat_bytes (0x7f); + return ~(((x & m) + m) | x | m); +} + +/* With similar caveats, identify bytes that are equal between X1 and X2. */ +static __always_inline find_t +find_eq_low (op_t x1, op_t x2) +{ + return find_zero_low (x1 ^ x2); +} + +static __always_inline find_t +find_eq_all (op_t x1, op_t x2) +{ + return find_zero_all (x1 ^ x2); +} + +/* With similar caveats, identify zero bytes in X1 and bytes that are + equal between in X1 and X2. */ +static __always_inline find_t +find_zero_eq_low (op_t x1, op_t x2) +{ + return find_zero_low (x1) | find_zero_low (x1 ^ x2); +} + +static __always_inline find_t +find_zero_eq_all (op_t x1, op_t x2) +{ + return find_zero_all (x1) | find_zero_all (x1 ^ x2); +} + +/* With similar caveats, identify zero bytes in X1 and bytes that are + not equal between in X1 and X2. */ +static __always_inline find_t +find_zero_ne_all (op_t x1, op_t x2) +{ + op_t m = repeat_bytes (0x7f); + op_t eq = x1 ^ x2; + op_t nz1 = ((x1 & m) + m) | x1; + op_t ne2 = ((eq & m) + m) | eq; + return (ne2 | ~nz1) & ~m; +} + +#endif /* _STRING_FZA_H */ diff --git a/sysdeps/generic/string-fzb.h b/sysdeps/generic/string-fzb.h new file mode 100644 index 0000000..42de500 --- /dev/null +++ b/sysdeps/generic/string-fzb.h @@ -0,0 +1,49 @@ +/* Zero byte detection, boolean. Generic C version. + Copyright (C) 2023 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <http://www.gnu.org/licenses/>. */ + +#ifndef _STRING_FZB_H +#define _STRING_FZB_H 1 + +#include <endian.h> +#include <string-fza.h> + +/* Determine if any byte within X is zero. This is a pure boolean test. */ + +static __always_inline _Bool +has_zero (op_t x) +{ + return find_zero_low (x) != 0; +} + +/* Likewise, but for byte equality between X1 and X2. */ + +static __always_inline _Bool +has_eq (op_t x1, op_t x2) +{ + return find_eq_low (x1, x2) != 0; +} + +/* Likewise, but for zeros in X1 and equal bytes between X1 and X2. */ + +static __always_inline _Bool +has_zero_eq (op_t x1, op_t x2) +{ + return find_zero_eq_low (x1, x2); +} + +#endif /* _STRING_FZB_H */ diff --git a/sysdeps/generic/string-fzc.h b/sysdeps/generic/string-fzc.h new file mode 100644 index 0000000..ae2f964 --- /dev/null +++ b/sysdeps/generic/string-fzc.h @@ -0,0 +1,87 @@ +/* Zero byte detection; indexes. Generic C version. + Copyright (C) 2023 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <http://www.gnu.org/licenses/>. */ + +#ifndef _STRING_FZC_H +#define _STRING_FZC_H 1 + +#include <endian.h> +#include <string-fza.h> +#include <string-fzi.h> + + +/* Given a word X that is known to contain a zero byte, return the index of + the first such within the word in memory order. */ +static __always_inline unsigned int +index_first_zero (op_t x) +{ + if (__BYTE_ORDER == __LITTLE_ENDIAN) + x = find_zero_low (x); + else + x = find_zero_all (x); + return index_first (x); +} + +/* Similarly, but perform the search for byte equality between X1 and X2. */ +static __always_inline unsigned int +index_first_eq (op_t x1, op_t x2) +{ + if (__BYTE_ORDER == __LITTLE_ENDIAN) + x1 = find_eq_low (x1, x2); + else + x1 = find_eq_all (x1, x2); + return index_first (x1); +} + +/* Similarly, but perform the search for zero within X1 or equality between + X1 and X2. */ +static __always_inline unsigned int +index_first_zero_eq (op_t x1, op_t x2) +{ + if (__BYTE_ORDER == __LITTLE_ENDIAN) + x1 = find_zero_eq_low (x1, x2); + else + x1 = find_zero_eq_all (x1, x2); + return index_first (x1); +} + +/* Similarly, but perform the search for zero within X1 or inequality between + X1 and X2. */ +static __always_inline unsigned int +index_first_zero_ne (op_t x1, op_t x2) +{ + return index_first (find_zero_ne_all (x1, x2)); +} + +/* Similarly, but search for the last zero within X. */ +static __always_inline unsigned int +index_last_zero (op_t x) +{ + if (__BYTE_ORDER == __LITTLE_ENDIAN) + x = find_zero_all (x); + else + x = find_zero_low (x); + return index_last (x); +} + +static __always_inline unsigned int +index_last_eq (op_t x1, op_t x2) +{ + return index_last_zero (x1 ^ x2); +} + +#endif /* STRING_FZC_H */ diff --git a/sysdeps/generic/string-fzi.h b/sysdeps/generic/string-fzi.h new file mode 100644 index 0000000..2deecef --- /dev/null +++ b/sysdeps/generic/string-fzi.h @@ -0,0 +1,71 @@ +/* Zero byte detection; indexes. Generic C version. + Copyright (C) 2023 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <http://www.gnu.org/licenses/>. */ + +#ifndef _STRING_FZI_H +#define _STRING_FZI_H 1 + +#include <limits.h> +#include <endian.h> +#include <string-fza.h> + +static __always_inline int +clz (find_t c) +{ + if (sizeof (find_t) == sizeof (unsigned long)) + return __builtin_clzl (c); + else + return __builtin_clzll (c); +} + +static __always_inline int +ctz (find_t c) +{ + if (sizeof (find_t) == sizeof (unsigned long)) + return __builtin_ctzl (c); + else + return __builtin_ctzll (c); +} + +/* A subroutine for the index_zero functions. Given a test word C, return + the (memory order) index of the first byte (in memory order) that is + non-zero. */ +static __always_inline unsigned int +index_first (find_t c) +{ + int r; + if (__BYTE_ORDER == __LITTLE_ENDIAN) + r = ctz (c); + else + r = clz (c); + return r / CHAR_BIT; +} + +/* Similarly, but return the (memory order) index of the last byte that is + non-zero. */ +static __always_inline unsigned int +index_last (find_t c) +{ + int r; + if (__BYTE_ORDER == __LITTLE_ENDIAN) + r = clz (c); + else + r = ctz (c); + return sizeof (find_t) - 1 - (r / CHAR_BIT); +} + +#endif /* STRING_FZI_H */ diff --git a/sysdeps/generic/string-misc.h b/sysdeps/generic/string-misc.h new file mode 100644 index 0000000..a119646 --- /dev/null +++ b/sysdeps/generic/string-misc.h @@ -0,0 +1,45 @@ +/* Miscellaneous functions used in string implementations. Generic C version. + Copyright (C) 2023 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <http://www.gnu.org/licenses/>. */ + +#ifndef _STRING_MISC_H +#define _STRING_MISC_H 1 + +#include <limits.h> +#include <endian.h> +#include <string-optype.h> + +/* Extract the byte at index IDX from word X, with index 0 being the + least significant byte. */ +static __always_inline unsigned char +extractbyte (op_t x, unsigned int idx) +{ + if (__BYTE_ORDER == __LITTLE_ENDIAN) + return x >> (idx * CHAR_BIT); + else + return x >> (sizeof (x) - 1 - idx) * CHAR_BIT; +} + +/* Setup an word with each byte being c_in. For instance, on a 64 bits + machine with input as 0xce the functions returns 0xcececececececece. */ +static __always_inline op_t +repeat_bytes (unsigned char c_in) +{ + return ((op_t)-1 / 0xff) * c_in; +} + +#endif /* _STRING_MISC_H */ diff --git a/sysdeps/generic/string-shift.h b/sysdeps/generic/string-shift.h new file mode 100644 index 0000000..9491e8b --- /dev/null +++ b/sysdeps/generic/string-shift.h @@ -0,0 +1,52 @@ +/* Shift unaligned word read Generic C version. + Copyright (C) 2023 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <http://www.gnu.org/licenses/>. */ + +#ifndef _STRING_SHIFT_H +#define _STRING_SHIFT_H 1 + +#include <endian.h> +#include <limits.h> +#include <stdint.h> +#include <string-fza.h> + +/* Return the mask WORD shifted based on S_INT address value, to ignore + values not presented in the aligned word read. */ +static __always_inline find_t +shift_find (find_t word, uintptr_t s) +{ + if (__BYTE_ORDER == __LITTLE_ENDIAN) + return word >> (CHAR_BIT * (s % sizeof (op_t))); + else + return word << (CHAR_BIT * (s % sizeof (op_t))); +} + +/* Mask off the bits defined for the S alignment value, or return WORD if + S is 0. */ +static __always_inline find_t +shift_find_last (find_t word, uintptr_t s) +{ + s = s % sizeof (op_t); + if (s == 0) + return word; + if (__BYTE_ORDER == __LITTLE_ENDIAN) + return word & ~(((op_t)-1) << (s * CHAR_BIT)); + else + return word & ~(((op_t)-1) >> (s * CHAR_BIT)); +} + +#endif /* _STRING_SHIFT_H */ |