arch/sparc/lib/checksum_32.S

Source file repositories/reference/linux-study-clean/arch/sparc/lib/checksum_32.S

File Facts

System
Linux kernel
Corpus path
arch/sparc/lib/checksum_32.S
Extension
.S
Size
14350 bytes
Lines
458
Domain
Architecture Layer
Bucket
arch/sparc
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>
#include <asm/errno.h>

#define CSUM_BIGCHUNK(buf, offset, sum, t0, t1, t2, t3, t4, t5)	\
	ldd	[buf + offset + 0x00], t0;			\
	ldd	[buf + offset + 0x08], t2;			\
	addxcc	t0, sum, sum;					\
	addxcc	t1, sum, sum;					\
	ldd	[buf + offset + 0x10], t4;			\
	addxcc	t2, sum, sum;					\
	addxcc	t3, sum, sum;					\
	ldd	[buf + offset + 0x18], t0;			\
	addxcc	t4, sum, sum;					\
	addxcc	t5, sum, sum;					\
	addxcc	t0, sum, sum;					\
	addxcc	t1, sum, sum;

#define CSUM_LASTCHUNK(buf, offset, sum, t0, t1, t2, t3)	\
	ldd	[buf - offset - 0x08], t0;			\
	ldd	[buf - offset - 0x00], t2;			\
	addxcc	t0, sum, sum;					\
	addxcc	t1, sum, sum;					\
	addxcc	t2, sum, sum;					\
	addxcc	t3, sum, sum;

	/* Do end cruft out of band to get better cache patterns. */
csum_partial_end_cruft:
	be	1f				! caller asks %o1 & 0x8
	 andcc	%o1, 4, %g0			! nope, check for word remaining
	ldd	[%o0], %g2			! load two
	addcc	%g2, %o2, %o2			! add first word to sum
	addxcc	%g3, %o2, %o2			! add second word as well
	add	%o0, 8, %o0			! advance buf ptr
	addx	%g0, %o2, %o2			! add in final carry
	andcc	%o1, 4, %g0			! check again for word remaining
1:	be	1f				! nope, skip this code
	 andcc	%o1, 3, %o1			! check for trailing bytes
	ld	[%o0], %g2			! load it
	addcc	%g2, %o2, %o2			! add to sum
	add	%o0, 4, %o0			! advance buf ptr
	addx	%g0, %o2, %o2			! add in final carry
	andcc	%o1, 3, %g0			! check again for trailing bytes
1:	be	1f				! no trailing bytes, return
	 addcc	%o1, -1, %g0			! only one byte remains?
	bne	2f				! at least two bytes more
	 subcc	%o1, 2, %o1			! only two bytes more?
	b	4f				! only one byte remains
	 or	%g0, %g0, %o4			! clear fake hword value
2:	lduh	[%o0], %o4			! get hword
	be	6f				! jmp if only hword remains
	 add	%o0, 2, %o0			! advance buf ptr either way
	sll	%o4, 16, %o4			! create upper hword
4:	ldub	[%o0], %o5			! get final byte
	sll	%o5, 8, %o5			! put into place
	or	%o5, %o4, %o4			! coalese with hword (if any)
6:	addcc	%o4, %o2, %o2			! add to sum
1:	retl					! get outta here
	 addx	%g0, %o2, %o0			! add final carry into retval

	/* Also do alignment out of band to get better cache patterns. */
csum_partial_fix_alignment:
	cmp	%o1, 6
	bl	cpte - 0x4
	 andcc	%o0, 0x2, %g0
	be	1f
	 andcc	%o0, 0x4, %g0
	lduh	[%o0 + 0x00], %g2
	sub	%o1, 2, %o1
	add	%o0, 2, %o0
	sll	%g2, 16, %g2

Annotation

Implementation Notes