/*
 *	cook - file construction tool
 *	Copyright (C) 1994, 1999, 2003 Peter Miller;
 *	All rights reserved.
 *
 *	This program 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 2 of the License, or
 *	(at your option) any later version.
 *
 *	This program 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 this program; if not, write to the Free Software
 *	Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
 *
 * MANIFEST: functions to manipulate crc32 fingerprints
 *
 * Derived from code marked:
 *	a few improvements by DJB 930708
 *	nonreverse table included by DJB 930622
 *	interface mods by DJB 930529
 *	COPYRIGHT (C) 1986 Gary S. Brown.  You may use this program, or
 *	code or tables extracted from it, as desired without restriction.
 *	X^32+X^26+X^23+X^22+X^16+X^12+X^11+X^10+X^8+X^7+X^5+X^4+X^2+X^1+X^0
 *	polynomial $edb88320
 */

#include <ac/stdio.h>

#include <fp/crc32.h>

#define CRC32_HASH_LEN 4

typedef struct crc32_ty crc32_ty;
struct crc32_ty
{
    FINGERPRINT_BASE_CLASS
    unsigned long   c;
    unsigned char   len[8];
};


static unsigned long crc_32_tab[] =
{
    0x00000000, 0x04c11db7, 0x09823b6e, 0x0d4326d9, 0x130476dc, 0x17c56b6b,
    0x1a864db2, 0x1e475005, 0x2608edb8, 0x22c9f00f, 0x2f8ad6d6, 0x2b4bcb61,
    0x350c9b64, 0x31cd86d3, 0x3c8ea00a, 0x384fbdbd, 0x4c11db70, 0x48d0c6c7,
    0x4593e01e, 0x4152fda9, 0x5f15adac, 0x5bd4b01b, 0x569796c2, 0x52568b75,
    0x6a1936c8, 0x6ed82b7f, 0x639b0da6, 0x675a1011, 0x791d4014, 0x7ddc5da3,
    0x709f7b7a, 0x745e66cd, 0x9823b6e0, 0x9ce2ab57, 0x91a18d8e, 0x95609039,
    0x8b27c03c, 0x8fe6dd8b, 0x82a5fb52, 0x8664e6e5, 0xbe2b5b58, 0xbaea46ef,
    0xb7a96036, 0xb3687d81, 0xad2f2d84, 0xa9ee3033, 0xa4ad16ea, 0xa06c0b5d,
    0xd4326d90, 0xd0f37027, 0xddb056fe, 0xd9714b49, 0xc7361b4c, 0xc3f706fb,
    0xceb42022, 0xca753d95, 0xf23a8028, 0xf6fb9d9f, 0xfbb8bb46, 0xff79a6f1,
    0xe13ef6f4, 0xe5ffeb43, 0xe8bccd9a, 0xec7dd02d, 0x34867077, 0x30476dc0,
    0x3d044b19, 0x39c556ae, 0x278206ab, 0x23431b1c, 0x2e003dc5, 0x2ac12072,
    0x128e9dcf, 0x164f8078, 0x1b0ca6a1, 0x1fcdbb16, 0x018aeb13, 0x054bf6a4,
    0x0808d07d, 0x0cc9cdca, 0x7897ab07, 0x7c56b6b0, 0x71159069, 0x75d48dde,
    0x6b93dddb, 0x6f52c06c, 0x6211e6b5, 0x66d0fb02, 0x5e9f46bf, 0x5a5e5b08,
    0x571d7dd1, 0x53dc6066, 0x4d9b3063, 0x495a2dd4, 0x44190b0d, 0x40d816ba,
    0xaca5c697, 0xa864db20, 0xa527fdf9, 0xa1e6e04e, 0xbfa1b04b, 0xbb60adfc,
    0xb6238b25, 0xb2e29692, 0x8aad2b2f, 0x8e6c3698, 0x832f1041, 0x87ee0df6,
    0x99a95df3, 0x9d684044, 0x902b669d, 0x94ea7b2a, 0xe0b41de7, 0xe4750050,
    0xe9362689, 0xedf73b3e, 0xf3b06b3b, 0xf771768c, 0xfa325055, 0xfef34de2,
    0xc6bcf05f, 0xc27dede8, 0xcf3ecb31, 0xcbffd686, 0xd5b88683, 0xd1799b34,
    0xdc3abded, 0xd8fba05a, 0x690ce0ee, 0x6dcdfd59, 0x608edb80, 0x644fc637,
    0x7a089632, 0x7ec98b85, 0x738aad5c, 0x774bb0eb, 0x4f040d56, 0x4bc510e1,
    0x46863638, 0x42472b8f, 0x5c007b8a, 0x58c1663d, 0x558240e4, 0x51435d53,
    0x251d3b9e, 0x21dc2629, 0x2c9f00f0, 0x285e1d47, 0x36194d42, 0x32d850f5,
    0x3f9b762c, 0x3b5a6b9b, 0x0315d626, 0x07d4cb91, 0x0a97ed48, 0x0e56f0ff,
    0x1011a0fa, 0x14d0bd4d, 0x19939b94, 0x1d528623, 0xf12f560e, 0xf5ee4bb9,
    0xf8ad6d60, 0xfc6c70d7, 0xe22b20d2, 0xe6ea3d65, 0xeba91bbc, 0xef68060b,
    0xd727bbb6, 0xd3e6a601, 0xdea580d8, 0xda649d6f, 0xc423cd6a, 0xc0e2d0dd,
    0xcda1f604, 0xc960ebb3, 0xbd3e8d7e, 0xb9ff90c9, 0xb4bcb610, 0xb07daba7,
    0xae3afba2, 0xaafbe615, 0xa7b8c0cc, 0xa379dd7b, 0x9b3660c6, 0x9ff77d71,
    0x92b45ba8, 0x9675461f, 0x8832161a, 0x8cf30bad, 0x81b02d74, 0x857130c3,
    0x5d8a9099, 0x594b8d2e, 0x5408abf7, 0x50c9b640, 0x4e8ee645, 0x4a4ffbf2,
    0x470cdd2b, 0x43cdc09c, 0x7b827d21, 0x7f436096, 0x7200464f, 0x76c15bf8,
    0x68860bfd, 0x6c47164a, 0x61043093, 0x65c52d24, 0x119b4be9, 0x155a565e,
    0x18197087, 0x1cd86d30, 0x029f3d35, 0x065e2082, 0x0b1d065b, 0x0fdc1bec,
    0x3793a651, 0x3352bbe6, 0x3e119d3f, 0x3ad08088, 0x2497d08d, 0x2056cd3a,
    0x2d15ebe3, 0x29d4f654, 0xc5a92679, 0xc1683bce, 0xcc2b1d17, 0xc8ea00a0,
    0xd6ad50a5, 0xd26c4d12, 0xdf2f6bcb, 0xdbee767c, 0xe3a1cbc1, 0xe760d676,
    0xea23f0af, 0xeee2ed18, 0xf0a5bd1d, 0xf464a0aa, 0xf9278673, 0xfde69bc4,
    0x89b8fd09, 0x8d79e0be, 0x803ac667, 0x84fbdbd0, 0x9abc8bd5, 0x9e7d9662,
    0x933eb0bb, 0x97ffad0c, 0xafb010b1, 0xab710d06, 0xa6322bdf, 0xa2f33668,
    0xbcb4666d, 0xb8757bda, 0xb5365d03, 0xb1f740b4
};


static void
reset(crc32_ty *c)
{
    c->c = 0;
    c->len[0] = 0;
    c->len[1] = 0;
    c->len[2] = 0;
    c->len[3] = 0;
    c->len[4] = 0;
    c->len[5] = 0;
    c->len[6] = 0;
    c->len[7] = 0;
}


static void
crc32_constructor(fingerprint_ty *p)
{
    crc32_ty        *c;

    c = (crc32_ty *)p;
    reset(c);
}


static void
crc32_destructor(fingerprint_ty *p)
{
}


static void
crc32_addn(fingerprint_ty *p, unsigned char *s, size_t n)
{
    crc32_ty	    *c;
    unsigned long   x;
    unsigned char   newc;
    int		    i;

    c = (crc32_ty *)p;
    i = n;
    while (i >= 256)
    {
	if (!++c->len[1])
	    if (!++c->len[2])
		if (!++c->len[3])
		    if (!++c->len[4])
	       		if (!++c->len[5])
			    if (!++c->len[6])
			     	++c->len[7];
	i -= 256;
    }
    newc = i;
    if ((c->len[0] += newc) < newc)
	if (!++c->len[1])
    	    if (!++c->len[2])
       		if (!++c->len[3])
	  	    if (!++c->len[4])
	     		if (!++c->len[5])
			    if (!++c->len[6])
	    			++c->len[7];
    i = n;
    x = c->c;
    while (i--)
	x = crc_32_tab[(int)((x >> 24) ^ *s++) & 0xff] ^ (x << 8);
    c->c = x;
}


static int
crc32_hash(fingerprint_ty *p, unsigned char *h)
{
    crc32_ty	    *c;
    unsigned long   x;
    unsigned char   len[8];
    int		    i;

    c = (crc32_ty *)p;
    for (i = 0; i < 8; ++i)
	len[i] = c->len[i];
    for (i = 7; i >= 0; --i)
	if (len[i])
    	    break;
    crc32_addn(p, len, i + 1);
    x = ~c->c;
    h[0] = x & 255;
    h[1] = (x >> 8) & 255;
    h[2] = (x >> 16) & 255;
    h[3] = (x >> 24) & 255;
    reset(c);
    return CRC32_HASH_LEN;
}


static void
crc32_sum(fingerprint_ty *p, char *obuf)
{
    unsigned char   h[CRC32_HASH_LEN];

    crc32_hash(p, h);
    sprintf(obuf, "%10lu", h[0] + 256L * (h[1] + 256L * (h[2] + 256L * h[3])));
}


fingerprint_methods_ty fp_crc32 =
{
    sizeof(crc32_ty),
    "crc32",
    crc32_constructor,
    crc32_destructor,
    crc32_addn,
    crc32_hash,
    crc32_sum
};
