// SPDX-License-Identifier: GPL-2.0
/*
 * arch/openrisc/lib/memcpy.c
 *
 * Optimized memory copy routines for openrisc.  These are mostly copied
 * from ohter sources but slightly entended based on ideas discuassed in
 * #openrisc.
 *
 * The word unroll implementation is an extension to the arm byte
 * unrolled implementation, but using word copies (if things are
 * properly aligned)
 *
 * The great arm loop unroll algorithm can be found at:
 *  arch/arm/boot/compressed/string.c
 */

#include <linux/export.h>

#include <linux/string.h>

#ifdef CONFIG_OR1K_1200
/*
 * Do memcpy with word copies and loop unrolling. This gives the
 * best performance on the OR1200 and MOR1KX archirectures
 */
void *memcpy(void *dest, __const void *src, __kernel_size_t n)
{
        int i = 0;
        unsigned char *d, *s;
        uint32_t *dest_w = (uint32_t *)dest, *src_w = (uint32_t *)src;

        /* If both source and dest are word aligned copy words */
        if (!((unsigned int)dest_w & 3) && !((unsigned int)src_w & 3)) {
                /* Copy 32 bytes per loop */
                for (i = n >> 5; i > 0; i--) {
                        *dest_w++ = *src_w++;
                        *dest_w++ = *src_w++;
                        *dest_w++ = *src_w++;
                        *dest_w++ = *src_w++;
                        *dest_w++ = *src_w++;
                        *dest_w++ = *src_w++;
                        *dest_w++ = *src_w++;
                        *dest_w++ = *src_w++;
                }

                if (n & 1 << 4) {
                        *dest_w++ = *src_w++;
                        *dest_w++ = *src_w++;
                        *dest_w++ = *src_w++;
                        *dest_w++ = *src_w++;
                }

                if (n & 1 << 3) {
                        *dest_w++ = *src_w++;
                        *dest_w++ = *src_w++;
                }

                if (n & 1 << 2)
                        *dest_w++ = *src_w++;

                d = (unsigned char *)dest_w;
                s = (unsigned char *)src_w;

        } else {
                d = (unsigned char *)dest_w;
                s = (unsigned char *)src_w;

                for (i = n >> 3; i > 0; i--) {
                        *d++ = *s++;
                        *d++ = *s++;
                        *d++ = *s++;
                        *d++ = *s++;
                        *d++ = *s++;
                        *d++ = *s++;
                        *d++ = *s++;
                        *d++ = *s++;
                }

                if (n & 1 << 2) {
                        *d++ = *s++;
                        *d++ = *s++;
                        *d++ = *s++;
                        *d++ = *s++;
                }
        }

        if (n & 1 << 1) {
                *d++ = *s++;
                *d++ = *s++;
        }

        if (n & 1)
                *d++ = *s++;

        return dest;
}
#else
/*
 * Use word copies but no loop unrolling as we cannot assume there
 * will be benefits on the archirecture
 */
void *memcpy(void *dest, __const void *src, __kernel_size_t n)
{
        unsigned char *d, *s;
        uint32_t *dest_w = (uint32_t *)dest, *src_w = (uint32_t *)src;

        /* If both source and dest are word aligned copy words */
        if (!((unsigned int)dest_w & 3) && !((unsigned int)src_w & 3)) {
                for (; n >= 4; n -= 4)
                        *dest_w++ = *src_w++;
        }

        d = (unsigned char *)dest_w;
        s = (unsigned char *)src_w;

        /* For remaining or if not aligned, copy bytes */
        for (; n >= 1; n -= 1)
                *d++ = *s++;

        return dest;

}
#endif

EXPORT_SYMBOL(memcpy);