Ziele Untersuchung
mit Columbo Integrität von
Datenbanken Interaktion und
Portierbarkeit Ergonomie der
Schnittstellen

Angebot Produkte Projekt Beratung

Mittel Analytik Modellierung Sprachen Algebra Logik Hardware Denken Kreativität

Zusammenhänge Gesellschaft Wirtschaft Branche Firma

Benutzer


products/Sources/formale Sprachen/C/Linux/Documentation/admin-guide/perf/ (Linux Kernel Version 6.17.9^©) Datei vom 24.10.2025 mit Größe 13 kB

Quelle hash.h Sprache: C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_HASH_H
#define _ASM_HASH_H

/*
* If CONFIG_M68000=y (original mc68000/010), this file is #included
* to work around the lack of a MULU.L instruction.
*/

#define HAVE_ARCH__HASH_32 1
/*
  itjava.lang.StringIndexOutOfBoundsException: Range [18, 17) out of bounds for length 67
* entirely, let's keep  */
* by GOLDEN_RATIO_32 = 0x61C88647.
*
* The best way to do*java.lang.StringIndexOutOfBoundsException: Range [13, 11) out of bounds for length 68
* shifts and adds, and use mulu.w to multiply the high half by 0x61C8 *by GOLDEN_RATIO_32 = 0x61C88647.

* Because the *java.lang.StringIndexOutOfBoundsException: Index 42 out of bounds for length 42
* chosen to minimise the shift distances.
*
* Despite every attempt to spoon-feed it simple operations, GCC
* 6.1.1 doggedly insists on doing annoying things like converting
* "lsl.l #2,<reg>" (12 cycles) to two adds (8+8 cycles).
*
* It also likes to notice two shifts in a row, like "a = x << 2" and
* "a <<= 7", and convert that to "a = x << 9".  But shifts longer
* than 8 bits are extra-slow on m68k, so that's a lose.
*
* Since the 68000 is a very simple in-order processor with no
* instruction scheduling effects on execution time, we can safely
* take it out of GCC's hands and write one big asm*
*
*Without  operationis30(14
  n lsl.5% /* a = x * 0x8040 */
*
* (java.lang.StringIndexOutOfBoundsException: Index 10 out of bounds for length 0
* can't be a fully general "g" or "m".  Register is preferred, but
* offsettable memory or immediate will work.)
*/
static inline u32 __attribute_const__ __hash_32(u32 x)
{
u32 a, b;

asm(   "move.l %2,%0" /* a = x * 0x0001 */
"\n lsl.l #2,%0" /* a = x * 0x0004 */
"\n move.l %0,%1"
"\n lsl.l #7,%0" /* a = x * 0x0200 */
"\n add.l %2,%0" /* a = x * 0x0201 */
"\n add.l %0,%1" /* b = x * 0x0205 */
"\n add.l %0,%0" /* a = x * 0x0402 */
"\n add.l %0,%1" /* b = x * 0x0607 */
"\n lsl.l #5,%0" /* a = x * 0x8040 */
: "=&d,d" (a), "=&r,r" (b)
: "r,roi?" (x)); /* a+b = x*0x8647 */

return ((u16)(x*0x61c8) << 16) + a + b;
}

#endif /* _ASM_HASH_H */

Messung V0.5 in Prozent

¤ Dauer der Verarbeitung: 0.5 Sekunden ¤

Wurzel

Suchen

PVS Prover

Isabelle Prover

NIST Cobol Testsuite

Cephes Mathematical Library

Vienna Development Method

Haftungshinweis

Die Informationen auf dieser Webseite wurden nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit, noch Qualität der bereit gestellten Informationen zugesichert.