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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/arch/sparc/lib/checksum_64.S
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/* SPDX-License-Identifier: GPL-2.0 */

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/* checksum.S: Sparc V9 optimized checksum code.

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 *

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 *  Copyright(C) 1995 Linus Torvalds

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 *  Copyright(C) 1995 Miguel de Icaza

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 *  Copyright(C) 1996, 2000 David S. Miller

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 *  Copyright(C) 1997 Jakub Jelinek

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 *

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 * derived from:

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 *	Linux/Alpha checksum c-code

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 *      Linux/ix86 inline checksum assembly

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 *      RFC1071 Computing the Internet Checksum (esp. Jacobsons m68k code)

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 *	David Mosberger-Tang for optimized reference c-code

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 *	BSD4.4 portable checksum routine

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 */

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#include <linux/export.h>

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	.text

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csum_partial_fix_alignment:

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	/* We checked for zero length already, so there must be

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	 * at least one byte.

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	 */

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	be,pt		%icc, 1f

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	 nop

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	ldub		[%o0 + 0x00], %o4

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	add		%o0, 1, %o0

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	sub		%o1, 1, %o1

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1:	andcc		%o0, 0x2, %g0

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	be,pn		%icc, csum_partial_post_align

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	 cmp		%o1, 2

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	blu,pn		%icc, csum_partial_end_cruft

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	 nop

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	lduh		[%o0 + 0x00], %o5

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	add		%o0, 2, %o0

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	sub		%o1, 2, %o1

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	ba,pt		%xcc, csum_partial_post_align

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	 add		%o5, %o4, %o4

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	.align		32

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	.globl		csum_partial

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	.type		csum_partial,#function

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	EXPORT_SYMBOL(csum_partial)

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csum_partial:		/* %o0=buff, %o1=len, %o2=sum */

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	prefetch	[%o0 + 0x000], #n_reads

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	clr		%o4

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	prefetch	[%o0 + 0x040], #n_reads

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	brz,pn		%o1, csum_partial_finish

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	 andcc		%o0, 0x3, %g0

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	/* We "remember" whether the lowest bit in the address

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	 * was set in %g7.  Because if it is, we have to swap

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	 * upper and lower 8 bit fields of the sum we calculate.

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	*/

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	bne,pn		%icc, csum_partial_fix_alignment

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	 andcc		%o0, 0x1, %g7

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csum_partial_post_align:

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	prefetch	[%o0 + 0x080], #n_reads

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	andncc		%o1, 0x3f, %o3

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	prefetch	[%o0 + 0x0c0], #n_reads

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	sub		%o1, %o3, %o1

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	brz,pn		%o3, 2f

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	 prefetch	[%o0 + 0x100], #n_reads

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	/* So that we don't need to use the non-pairing

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	 * add-with-carry instructions we accumulate 32-bit

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	 * values into a 64-bit register.  At the end of the

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	 * loop we fold it down to 32-bits and so on.

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	 */

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	prefetch	[%o0 + 0x140], #n_reads

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1:	lduw		[%o0 + 0x00], %o5

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	lduw		[%o0 + 0x04], %g1

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	lduw		[%o0 + 0x08], %g2

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	add		%o4, %o5, %o4

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	lduw		[%o0 + 0x0c], %g3

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	add		%o4, %g1, %o4

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	lduw		[%o0 + 0x10], %o5

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	add		%o4, %g2, %o4

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	lduw		[%o0 + 0x14], %g1

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	add		%o4, %g3, %o4

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	lduw		[%o0 + 0x18], %g2

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	add		%o4, %o5, %o4

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	lduw		[%o0 + 0x1c], %g3

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	add		%o4, %g1, %o4

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	lduw		[%o0 + 0x20], %o5

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	add		%o4, %g2, %o4

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	lduw		[%o0 + 0x24], %g1

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	add		%o4, %g3, %o4

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	lduw		[%o0 + 0x28], %g2

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	add		%o4, %o5, %o4

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	lduw		[%o0 + 0x2c], %g3

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	add		%o4, %g1, %o4

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	lduw		[%o0 + 0x30], %o5

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	add		%o4, %g2, %o4

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	lduw		[%o0 + 0x34], %g1

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	add		%o4, %g3, %o4

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	lduw		[%o0 + 0x38], %g2

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	add		%o4, %o5, %o4

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	lduw		[%o0 + 0x3c], %g3

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	add		%o4, %g1, %o4

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	prefetch	[%o0 + 0x180], #n_reads

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	add		%o4, %g2, %o4

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	subcc		%o3, 0x40, %o3

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	add		%o0, 0x40, %o0

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	bne,pt		%icc, 1b

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	 add		%o4, %g3, %o4

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2:	and		%o1, 0x3c, %o3

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	brz,pn		%o3, 2f

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	 sub		%o1, %o3, %o1

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1:	lduw		[%o0 + 0x00], %o5

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	subcc		%o3, 0x4, %o3

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	add		%o0, 0x4, %o0

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	bne,pt		%icc, 1b

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	 add		%o4, %o5, %o4

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2:

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	/* fold 64-->32 */

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	srlx		%o4, 32, %o5

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	srl		%o4, 0, %o4

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	add		%o4, %o5, %o4

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	srlx		%o4, 32, %o5

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	srl		%o4, 0, %o4

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	add		%o4, %o5, %o4

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	/* fold 32-->16 */

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	sethi		%hi(0xffff0000), %g1

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	srl		%o4, 16, %o5

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	andn		%o4, %g1, %g2

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	add		%o5, %g2, %o4

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	srl		%o4, 16, %o5

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	andn		%o4, %g1, %g2

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	add		%o5, %g2, %o4

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csum_partial_end_cruft:

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	/* %o4 has the 16-bit sum we have calculated so-far.  */

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	cmp		%o1, 2

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	blu,pt		%icc, 1f

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	 nop

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	lduh		[%o0 + 0x00], %o5

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	sub		%o1, 2, %o1

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	add		%o0, 2, %o0

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	add		%o4, %o5, %o4

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1:	brz,pt		%o1, 1f

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	 nop

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	ldub		[%o0 + 0x00], %o5

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	sub		%o1, 1, %o1

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	add		%o0, 1, %o0

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	sllx		%o5, 8, %o5

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	add		%o4, %o5, %o4

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1:

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	/* fold 32-->16 */

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	sethi		%hi(0xffff0000), %g1

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	srl		%o4, 16, %o5

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	andn		%o4, %g1, %g2

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	add		%o5, %g2, %o4

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	srl		%o4, 16, %o5

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	andn		%o4, %g1, %g2

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	add		%o5, %g2, %o4

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1:	brz,pt		%g7, 1f

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	 nop

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	/* We started with an odd byte, byte-swap the result.  */

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	srl		%o4, 8, %o5

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	and		%o4, 0xff, %g1

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	sll		%g1, 8, %g1

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	or		%o5, %g1, %o4

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1:	addcc		%o2, %o4, %o2

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	addc		%g0, %o2, %o2

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csum_partial_finish:

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	retl

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	 srl		%o2, 0, %o0

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