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/usr/src/linux-headers-5.15.0-181/arch/microblaze/include/asm/

/usr/src/linux-headers-5.15.0-181/arch/microblaze/include/asm

Name	Size	Mode	Actions
asm-compat.h	518	0644	edit dl rm
asm-offsets.h	35	0644	edit dl rm
barrier.h	313	0644	edit dl rm
cache.h	510	0644	edit dl rm
cacheflush.h	3209	0644	edit dl rm
checksum.h	806	0644	edit dl rm
cpuinfo.h	2043	0644	edit dl rm
current.h	714	0644	edit dl rm
delay.h	2138	0644	edit dl rm
dma.h	432	0644	edit dl rm
elf.h	602	0644	edit dl rm
entry.h	1018	0644	edit dl rm
exceptions.h	1928	0644	edit dl rm
fixmap.h	1874	0644	edit dl rm
flat.h	1982	0644	edit dl rm
ftrace.h	642	0644	edit dl rm
futex.h	2179	0644	edit dl rm
hash.h	2429	0644	edit dl rm
highmem.h	1800	0644	edit dl rm
io.h	1691	0644	edit dl rm
irq.h	376	0644	edit dl rm
irqflags.h	2529	0644	edit dl rm
Kbuild	250	0644	edit dl rm
kgdb.h	739	0644	edit dl rm
mmu.h	4050	0644	edit dl rm
mmu_context.h	72	0644	edit dl rm
mmu_context_mm.h	3893	0644	edit dl rm
module.h	704	0644	edit dl rm
page.h	4076	0644	edit dl rm
pci-bridge.h	4473	0644	edit dl rm
pci.h	1986	0644	edit dl rm
pgalloc.h	1042	0644	edit dl rm
pgtable.h	14526	0644	edit dl rm
processor.h	2693	0644	edit dl rm
ptrace.h	591	0644	edit dl rm
pvr.h	8791	0644	edit dl rm
registers.h	1508	0644	edit dl rm
seccomp.h	256	0644	edit dl rm
sections.h	501	0644	edit dl rm
setup.h	823	0644	edit dl rm
string.h	494	0644	edit dl rm
switch_to.h	493	0644	edit dl rm
syscall.h	2346	0644	edit dl rm
thread_info.h	3979	0644	edit dl rm
timex.h	266	0644	edit dl rm
tlbflush.h	1579	0644	edit dl rm
uaccess.h	8121	0644	edit dl rm
unistd.h	1051	0644	edit dl rm
unwind.h	611	0644	edit dl rm
vmalloc.h	108	0644	edit dl rm

Edit: /usr/src/linux-headers-5.15.0-181/arch/microblaze/include/asm/hash.h (2429B)

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

/*
 * Fortunately, most people who want to run Linux on Microblaze enable
 * both multiplier and barrel shifter, but omitting them is technically
 * a supported configuration.
 *
 * With just a barrel shifter, we can implement an efficient constant
 * multiply using shifts and adds.  GCC can find a 9-step solution, but
 * this 6-step solution was found by Yevgen Voronenko's implementation
 * of the Hcub algorithm at http://spiral.ece.cmu.edu/mcm/gen.html.
 *
 * That software is really not designed for a single multiplier this large,
 * but if you run it enough times with different seeds, it'll find several
 * 6-shift, 6-add sequences for computing x * 0x61C88647.  They are all
 *	c = (x << 19) + x;
 *	a = (x <<  9) + c;
 *	b = (x << 23) + a;
 *	return (a<<11) + (b<<6) + (c<<3) - b;
 * with variations on the order of the final add.
 *
 * Without even a shifter, it's hopless; any hash function will suck.
 */

#if CONFIG_XILINX_MICROBLAZE0_USE_HW_MUL == 0

#define HAVE_ARCH__HASH_32 1

/* Multiply by GOLDEN_RATIO_32 = 0x61C88647 */
static inline u32 __attribute_const__ __hash_32(u32 a)
{
#if CONFIG_XILINX_MICROBLAZE0_USE_BARREL
	unsigned int b, c;

/* Phase 1: Compute three intermediate values */
	b =  a << 23;
	c = (a << 19) + a;
	a = (a <<  9) + c;
	b += a;

/* Phase 2: Compute (a << 11) + (b << 6) + (c << 3) - b */
	a <<= 5;
	a += b;		/* (a << 5) + b */
	a <<= 3;
	a += c;		/* (a << 8) + (b << 3) + c */
	a <<= 3;
	return a - b;	/* (a << 11) + (b << 6) + (c << 3) - b */
#else
	/*
	 * "This is really going to hurt."
	 *
	 * Without a barrel shifter, left shifts are implemented as
	 * repeated additions, and the best we can do is an optimal
	 * addition-subtraction chain.  This one is not known to be
	 * optimal, but at 37 steps, it's decent for a 31-bit multiplier.
	 *
	 * Question: given its size (37*4 = 148 bytes per instance),
	 * and slowness, is this worth having inline?
	 */
	unsigned int b, c, d;

b = a << 4;	/* 4    */
	c = b << 1;	/* 1  5 */
	b += a;		/* 1  6 */
	c += b;		/* 1  7 */
	c <<= 3;	/* 3 10 */
	c -= a;		/* 1 11 */
	d = c << 7;	/* 7 18 */
	d += b;		/* 1 19 */
	d <<= 8;	/* 8 27 */
	d += a;		/* 1 28 */
	d <<= 1;	/* 1 29 */
	d += b;		/* 1 30 */
	d <<= 6;	/* 6 36 */
	return d + c;	/* 1 37 total instructions*/
#endif
}

#endif /* !CONFIG_XILINX_MICROBLAZE0_USE_HW_MUL */
#endif /* _ASM_HASH_H */

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