diff --git a/sysdeps/generic/string-extbyte.h b/sysdeps/generic/string-extbyte.h
new file mode 100644
index 0000000000..38b4674dca
--- /dev/null
+++ b/sysdeps/generic/string-extbyte.h
@@ -0,0 +1,37 @@
+/* Extract by from memory word. 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
+ . */
+
+#ifndef _STRING_EXTBYTE_H
+#define _STRING_EXTBYTE_H 1
+
+#include
+#include
+#include
+
+/* 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;
+}
+
+#endif /* _STRING_EXTBYTE_H */
diff --git a/sysdeps/generic/string-fza.h b/sysdeps/generic/string-fza.h
new file mode 100644
index 0000000000..32bb9f06c2
--- /dev/null
+++ b/sysdeps/generic/string-fza.h
@@ -0,0 +1,116 @@
+/* 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
+ . */
+
+#ifndef _STRING_FZA_H
+#define _STRING_FZA_H 1
+
+#include
+#include
+#include
+
+/* The function return a byte mask. */
+typedef unsigned long int find_t;
+
+/* 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)));
+}
+
+/* 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_low (op_t x1, op_t x2)
+{
+ return (~find_zero_eq_low (x1, x2)) + 1;
+}
+
+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 0000000000..42de500d67
--- /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
+ . */
+
+#ifndef _STRING_FZB_H
+#define _STRING_FZB_H 1
+
+#include
+#include
+
+/* 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-fzi.h b/sysdeps/generic/string-fzi.h
new file mode 100644
index 0000000000..b1fd4d34b3
--- /dev/null
+++ b/sysdeps/generic/string-fzi.h
@@ -0,0 +1,135 @@
+/* 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
+ . */
+
+#ifndef _STRING_FZI_H
+#define _STRING_FZI_H 1
+
+#include
+#include
+#include
+
+static __always_inline int
+clz (op_t c)
+{
+ if (sizeof (op_t) == sizeof (unsigned long))
+ return __builtin_clzl (c);
+ else
+ return __builtin_clzll (c);
+}
+
+static __always_inline int
+ctz (op_t c)
+{
+ if (sizeof (op_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 (op_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 (op_t c)
+{
+ int r;
+ if (__BYTE_ORDER == __LITTLE_ENDIAN)
+ r = clz (c);
+ else
+ r = ctz (c);
+ return sizeof (op_t) - 1 - (r / CHAR_BIT);
+}
+
+/* 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)
+{
+ if (__BYTE_ORDER == __LITTLE_ENDIAN)
+ x1 = find_zero_ne_low (x1, x2);
+ else
+ x1 = find_zero_ne_all (x1, x2);
+ return index_first (x1);
+}
+
+/* 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_FZI_H */