[Skiboot] [PATCH 05/15] libc/string: Add memcpy_ci

[Stewart Smith]

Claudio Carvalho <cclaudio at linux.vnet.ibm.com> writes:
> --- /dev/null
> +++ b/libc/string/memcpy_ci.c
> @@ -0,0 +1,50 @@
> +/* Copyright 2013-2016 IBM Corp
> + *
> + * Licensed under the Apache License, Version 2.0 (the "License");
> + * you may not use this file except in compliance with the License.
> + * You may obtain a copy of the License at
> + *
> + *      http://www.apache.org/licenses/LICENSE-2.0
> + *
> + * Unless required by applicable law or agreed to in writing, software
> + * distributed under the License is distributed on an "AS IS" BASIS,
> + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
> + * implied.
> + * See the License for the specific language governing permissions and
> + * limitations under the License.
> + */
> +
> +#include <string.h>
> +#include <io.h>
> +
> +const void* memcpy_ci(const void *destpp, const void *srcpp, size_t len)
> +{
> +	size_t i;
> +	const size_t block = sizeof(uint32_t);
> +
> +	unsigned long int destp = (long int) destpp;
> +	unsigned long int srcp = (long int) srcpp;

Here you're casting away const which isn't good.

The const for destpp is incorrect as what destpp points to certainly
isn't untouched by this function.

Same with return value, shouldn't be const.

> +
> +	/* copy just a few bytes to make dst aligned */
> +	i = len % block;
> +	while (i > 0)
> +	{
> +		*((uint8_t*) destp) = in_8((uint8_t*)srcp);
> +		srcp += 1;
> +		destp += 1;
> +		i--;
> +	}
> +
> +	len -= len % block;
> +
> +	/* copy the aligned bytes */
> +	while(len > 0)
> +	{
> +		*((uint32_t*) destp) = in_be32((uint32_t*)srcp);
> +		srcp += block;
> +		destp += block;
> +		len -= block;
> +	}
> +
> +	return destpp;
> +}

I think it would be good to add a unit test for this function.

It also (currently) assumes that src is a multiple of uint32_t, although
nothing checks that and so would silently fail if called for, say 33 bytes.

-- 
Stewart Smith
OPAL Architect, IBM.