[glibc/azanella/generic-strings] powerpc: Add string-fza.h

[Adhemerval Zanella <azanella@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=a86c47f74ee2bbb1f2943ba1086a183aa29e59b0

commit a86c47f74ee2bbb1f2943ba1086a183aa29e59b0
Author: Richard Henderson <richard.henderson@linaro.org>
Date:   Tue Jan 10 18:01:05 2023 -0300

    powerpc: Add string-fza.h
    
    While ppc has the more important string functions in assembly,
    there are still a few generic routines used.
    
    Use the Power 6 CMPB insn for testing of zeros.
    
    Checked on powerpc64le-linux-gnu.

Diff:
---
 sysdeps/powerpc/string-fza.h | 95 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 95 insertions(+)

diff --git a/sysdeps/powerpc/string-fza.h b/sysdeps/powerpc/string-fza.h
new file mode 100644
index 0000000000..13de16a004
--- /dev/null
+++ b/sysdeps/powerpc/string-fza.h
@@ -0,0 +1,95 @@
+/* Zero byte detection; basics.  PowerPC 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 _POWERPC_STRING_FZA_H
+#define _POWERPC_STRING_FZA_H 1
+
+/* PowerISA 2.05 (POWER6) provides cmpb instruction.  */
+#ifdef _ARCH_PWR6
+# include <limits.h>
+# include <endian.h>
+# include <stdint.h>
+# include <string-maskoff.h>
+# include <string-optype.h>
+
+/* The functions return a byte mask.  */
+typedef op_t 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)));
+}
+
+/* Mask off the bits defined the the S alignment value.  */
+static __always_inline find_t
+shift_find_last (find_t word, uintptr_t s)
+{
+   return word & create_mask (s);
+}
+
+/* This function returns 0xff for each byte that is
+   equal between X1 and X2.  */
+
+static __always_inline find_t
+find_eq_all (op_t x1, op_t x2)
+{
+  op_t ret;
+  asm ("cmpb %0,%1,%2" : "=r"(ret) : "r"(x1), "r"(x2));
+  return ret;
+}
+
+/* This function returns 0xff for each byte that is zero in X.  */
+
+static __always_inline find_t
+find_zero_all (op_t x)
+{
+  return find_eq_all (x, 0);
+}
+
+/* Identify zero bytes in X1 or equality between X1 and X2.  */
+
+static __always_inline find_t
+find_zero_eq_all (op_t x1, op_t x2)
+{
+  return find_zero_all (x1) | find_eq_all (x1, x2);
+}
+
+/* Identify zero bytes in X1 or inequality between X1 and X2.  */
+
+static __always_inline find_t
+find_zero_ne_all (op_t x1, op_t x2)
+{
+  return find_zero_all (x1) | ~find_eq_all (x1, x2);
+}
+
+/* Define the "inexact" versions in terms of the exact versions.  */
+# define find_zero_low		find_zero_all
+# define find_eq_low		find_eq_all
+# define find_zero_eq_low	find_zero_eq_all
+# define find_zero_ne_low	find_zero_ne_all
+#else
+# include <sysdeps/generic/string-fza.h>
+#endif /* _ARCH_PWR6  */
+
+#endif /* _POWERPC_STRING_FZA_H  */