/* adler32.c - adler32 check. */
/*
* GRUB -- GRand Unified Bootloader
* Copyright (C) 2011 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/types.h>
#include <grub/dl.h>
#include <grub/crypto.h>
GRUB_MOD_LICENSE ("GPLv3+");
/* Based on adler32() from adler32.c of zlib-1.2.5 library. */
#define BASE 65521UL
#define NMAX 5552
#define DO1(buf,i) {adler += (buf)[i]; sum2 += adler;}
#define DO2(buf,i) DO1(buf,i); DO1(buf,i+1);
#define DO4(buf,i) DO2(buf,i); DO2(buf,i+2);
#define DO8(buf,i) DO4(buf,i); DO4(buf,i+4);
#define DO16(buf) DO8(buf,0); DO8(buf,8);
static grub_uint32_t
update_adler32 (grub_uint32_t adler, const grub_uint8_t *buf, grub_size_t len)
{
unsigned long sum2;
unsigned int n;
sum2 = (adler >> 16) & 0xffff;
adler &= 0xffff;
if (len == 1)
{
adler += buf[0];
if (adler >= BASE)
adler -= BASE;
sum2 += adler;
if (sum2 >= BASE)
sum2 -= BASE;
return adler | (sum2 << 16);
}
if (len < 16)
{
while (len--)
{
adler += *buf++;
sum2 += adler;
}
if (adler >= BASE)
adler -= BASE;
sum2 %= BASE;
return adler | (sum2 << 16);
}
while (len >= NMAX)
{
len -= NMAX;
n = NMAX / 16;
do
{
DO16 (buf);
buf += 16;
}
while (--n);
adler %= BASE;
sum2 %= BASE;
}
if (len)
{
while (len >= 16)
{
len -= 16;
DO16 (buf);
buf += 16;
}
while (len--)
{
adler += *buf++;
sum2 += adler;
}
adler %= BASE;
sum2 %= BASE;
}
return adler | (sum2 << 16);
}
typedef struct
{
grub_uint32_t adler;
}
adler32_context;
static void
adler32_init (void *context)
{
adler32_context *ctx = (adler32_context *) context;
ctx->adler = 1;
}
static void
adler32_write (void *context, const void *inbuf, grub_size_t inlen)
{
adler32_context *ctx = (adler32_context *) context;
if (!inbuf)
return;
ctx->adler = update_adler32 (ctx->adler, inbuf, inlen);
}
static grub_uint8_t *
adler32_read (void *context)
{
adler32_context *ctx = (adler32_context *) context;
return (grub_uint8_t *) &ctx->adler;
}
static void
adler32_final (void *context __attribute__ ((unused)))
{
}
gcry_md_spec_t _gcry_digest_spec_adler32 = {
"ADLER32",0 , 0, 0 , 4,
adler32_init, adler32_write, adler32_final, adler32_read,
sizeof (adler32_context),
.blocksize = 64
};
GRUB_MOD_INIT(adler32)
{
grub_md_register (&_gcry_digest_spec_adler32);
}
GRUB_MOD_FINI(adler32)
{
grub_md_unregister (&_gcry_digest_spec_adler32);
}