lib/raid/raid6/powerpc/altivec.uc

Source file repositories/reference/linux-study-clean/lib/raid/raid6/powerpc/altivec.uc

File Facts

System
Linux kernel
Corpus path
lib/raid/raid6/powerpc/altivec.uc
Extension
.uc
Size
3051 bytes
Lines
111
Domain
Kernel Services
Bucket
lib
Inferred role
Kernel Services: lib
Status
atlas-only

Why This File Exists

Shared kernel service surface used by multiple subsystems, including helpers, cryptography, virtualization support, and async I/O infrastructure.

Dependency Surface

Detected Declarations

Annotated Snippet

#include "algos.h"

#include <altivec.h>
#include <asm/cputable.h>
#include <asm/switch_to.h>

/*
 * This is the C data type to use.  We use a vector of
 * signed char so vec_cmpgt() will generate the right
 * instruction.
 */

typedef vector signed char unative_t;

#define NBYTES(x) ((vector signed char) {x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x})
#define NSIZE	sizeof(unative_t)

/*
 * The SHLBYTE() operation shifts each byte left by 1, *not*
 * rolling over into the next byte
 */
static inline __attribute_const__ unative_t SHLBYTE(unative_t v)
{
	return vec_add(v,v);
}

/*
 * The MASK() operation returns 0xFF in any byte for which the high
 * bit is 1, 0x00 for any byte for which the high bit is 0.
 */
static inline __attribute_const__ unative_t MASK(unative_t v)
{
	unative_t zv = NBYTES(0);

	/* vec_cmpgt returns a vector bool char; thus the need for the cast */
	return (unative_t)vec_cmpgt(zv, v);
}


/* This is noinline to make damned sure that gcc doesn't move any of the
   Altivec code around the enable/disable code */
static void noinline
raid6_altivec$#_gen_syndrome_real(int disks, size_t bytes, void **ptrs)
{
	u8 **dptr = (u8 **)ptrs;
	u8 *p, *q;
	int d, z, z0;

	unative_t wd$$, wq$$, wp$$, w1$$, w2$$;
	unative_t x1d = NBYTES(0x1d);

	z0 = disks - 3;		/* Highest data disk */
	p = dptr[z0+1];		/* XOR parity */
	q = dptr[z0+2];		/* RS syndrome */

	for ( d = 0 ; d < bytes ; d += NSIZE*$# ) {
		wq$$ = wp$$ = *(unative_t *)&dptr[z0][d+$$*NSIZE];
		for ( z = z0-1 ; z >= 0 ; z-- ) {
			wd$$ = *(unative_t *)&dptr[z][d+$$*NSIZE];
			wp$$ = vec_xor(wp$$, wd$$);
			w2$$ = MASK(wq$$);
			w1$$ = SHLBYTE(wq$$);
			w2$$ = vec_and(w2$$, x1d);
			w1$$ = vec_xor(w1$$, w2$$);
			wq$$ = vec_xor(w1$$, wd$$);
		}
		*(unative_t *)&p[d+NSIZE*$$] = wp$$;
		*(unative_t *)&q[d+NSIZE*$$] = wq$$;
	}
}

Annotation

Implementation Notes