arch/alpha/lib/ev6-csum_ipv6_magic.S

Source file repositories/reference/linux-study-clean/arch/alpha/lib/ev6-csum_ipv6_magic.S

File Facts

System
Linux kernel
Corpus path
arch/alpha/lib/ev6-csum_ipv6_magic.S
Extension
.S
Size
5304 bytes
Lines
154
Domain
Architecture Layer
Bucket
arch/alpha
Inferred role
Architecture Layer: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

#include <linux/export.h>
	.globl csum_ipv6_magic
	.align 4
	.ent csum_ipv6_magic
	.frame $30,0,$26,0
csum_ipv6_magic:
	.prologue 0

	ldq_u	$0,0($16)	# L : Latency: 3
	inslh	$18,7,$4	# U : 0000000000AABBCC
	ldq_u	$1,8($16)	# L : Latency: 3
	sll	$19,8,$7	# U : U L U L : 0x00000000 00aabb00

	and	$16,7,$6	# E : src misalignment
	ldq_u	$5,15($16)	# L : Latency: 3
	zapnot	$20,15,$20	# U : zero extend incoming csum
	ldq_u	$2,0($17)	# L : U L U L : Latency: 3

	extql	$0,$6,$0	# U :
	extqh	$1,$6,$22	# U :
	ldq_u	$3,8($17)	# L : Latency: 3
	sll	$19,24,$19	# U : U U L U : 0x000000aa bb000000

	cmoveq	$6,$31,$22	# E : src aligned?
	ldq_u	$23,15($17)	# L : Latency: 3
	inswl	$18,3,$18	# U : 000000CCDD000000
	addl	$19,$7,$19	# E : U L U L : <sign bits>bbaabb00

	or	$0,$22,$0	# E : 1st src word complete
	extql	$1,$6,$1	# U :
	or	$18,$4,$18	# E : 000000CCDDAABBCC
	extqh	$5,$6,$5	# U : L U L U

	and	$17,7,$6	# E : dst misalignment
	extql	$2,$6,$2	# U :
	or	$1,$5,$1	# E : 2nd src word complete
	extqh	$3,$6,$22	# U : L U L U :

	cmoveq	$6,$31,$22	# E : dst aligned?
	extql	$3,$6,$3	# U :
	addq	$20,$0,$20	# E : begin summing the words
	extqh	$23,$6,$23	# U : L U L U :

	srl	$18,16,$4	# U : 0000000000CCDDAA
	or	$2,$22,$2	# E : 1st dst word complete
	zap	$19,0x3,$19	# U : <sign bits>bbaa0000
	or	$3,$23,$3	# E : U L U L : 2nd dst word complete

	cmpult	$20,$0,$0	# E :
	addq	$20,$1,$20	# E :
	zapnot	$18,0xa,$18	# U : 00000000DD00BB00
	zap	$4,0xa,$4	# U : U U L L : 0000000000CC00AA

	or	$18,$4,$18	# E : 00000000DDCCBBAA
	nop			# E :
	cmpult	$20,$1,$1	# E :
	addq	$20,$2,$20	# E : U L U L

	cmpult	$20,$2,$2	# E :
	addq	$20,$3,$20	# E :
	cmpult	$20,$3,$3	# E : (1 cycle stall on $20)
	addq	$20,$18,$20	# E : U L U L (1 cycle stall on $20)

	cmpult	$20,$18,$18	# E :
	addq	$20,$19,$20	# E : (1 cycle stall on $20)
	addq	$0,$1,$0	# E : merge the carries back into the csum
	addq	$2,$3,$2	# E :

	cmpult	$20,$19,$19	# E :
	addq	$18,$19,$18	# E : (1 cycle stall on $19)

Annotation

Implementation Notes