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/*
* GRUB -- GRand Unified Bootloader
* Copyright (C) 2012 Free Software Foundation, Inc.
*
* GRUB is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* GRUB is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GRUB. If not, see <http://www.gnu.org/licenses/>.
*/
#include <grub/dl.h>
#include <grub/crypto.h>
GRUB_MOD_LICENSE ("GPLv3+");
struct adler32_context
{
grub_uint16_t a, b;
grub_uint32_t c;
};
static void
adler32_init (void *context)
{
struct adler32_context *ctx = context;
ctx->a = 1;
ctx->b = 0;
}
#define MOD 65521
static grub_uint16_t
mod_add (grub_uint16_t a, grub_uint16_t b)
{
if ((grub_uint32_t) a + (grub_uint32_t) b >= MOD)
return a + b - MOD;
return a + b;
}
static void
adler32_write (void *context, const void *inbuf, grub_size_t inlen)
{
struct adler32_context *ctx = context;
const grub_uint8_t *ptr = inbuf;
while (inlen)
{
ctx->a = mod_add (ctx->a, *ptr);
ctx->b = mod_add (ctx->a, ctx->b);
inlen--;
ptr++;
}
}
static void
adler32_final (void *context __attribute__ ((unused)))
{
}
static grub_uint8_t *
adler32_read (void *context)
{
struct adler32_context *ctx = context;
if (ctx->a > MOD)
ctx->a -= MOD;
if (ctx->b > MOD)
ctx->b -= MOD;
ctx->c = grub_cpu_to_be32 (ctx->a | (ctx->b << 16));
return (grub_uint8_t *) &ctx->c;
}
static gcry_md_spec_t spec_adler32 =
{
"ADLER32", 0, 0, 0, 4,
adler32_init, adler32_write, adler32_final, adler32_read,
sizeof (struct adler32_context),
#ifdef GRUB_UTIL
.modname = "adler32",
#endif
.blocksize = 64
};
GRUB_MOD_INIT(adler32)
{
grub_md_register (&spec_adler32);
}
GRUB_MOD_FINI(adler32)
{
grub_md_unregister (&spec_adler32);
}
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