#include "../common.h"

#ifdef i386
#define HAVE_ROTATE
#endif

#ifdef HAVE_ROTATE
#define ROL(n,a) ((a) = (((a) << (n)) | ((a) >> 8*sizeof(a)-(n))))
#define ROR(n,a) ((a) = (((a) >> (n)) | ((a) << 8*sizeof(a)-(n))))
#else
#define ROL(n,a) ((a) = (((a) << (n)) ^ ((a) >> 8*sizeof(a)-(n))))
#define ROR(n,a) ((a) = (((a) >> (n)) ^ ((a) << 8*sizeof(a)-(n))))
#endif

static unsigned char T[] = {
    1, 87, 49, 12, 176, 178, 102, 166, 121, 193, 6, 84, 249, 230, 44, 163,
    14, 197, 213, 181, 161, 85, 218, 80, 64, 239, 24, 226, 236, 142, 38, 200,
    110, 177, 104, 103, 141, 253, 255, 50, 77, 101, 81, 18, 45, 96, 31, 222,
    25, 107, 190, 70, 86, 237, 240, 34, 72, 242, 20, 214, 244, 227, 149, 235,
    97, 234, 57, 22, 60, 250, 82, 175, 208, 5, 127, 199, 111, 62, 135, 248,
    174, 169, 211, 58, 66, 154, 106, 195, 245, 171, 17, 187, 182, 179, 0, 243,
    132, 56, 148, 75, 128, 133, 158, 100, 130, 126, 91, 13, 153, 246, 216, 219,
    119, 68, 223, 78, 83, 88, 201, 99, 122, 11, 92, 32, 136, 114, 52, 10,
    138, 30, 48, 183, 156, 35, 61, 26, 143, 74, 251, 94, 129, 162, 63, 152,
    170, 7, 115, 167, 241, 206, 3, 150, 55, 59, 151, 220, 90, 53, 23, 131, 
    125, 173, 15, 238, 79, 95, 89, 16, 105, 137, 225, 224, 217, 160, 37, 123,
    118, 73, 2, 157, 46, 116, 9, 145, 134, 228, 207, 212, 202, 215, 69, 229,
    27, 188, 67, 124, 168, 252, 42, 4, 29, 108, 21, 247, 19, 205, 39, 203,
    233, 40, 186, 147, 198, 192, 155, 33, 164, 191, 98, 204, 165, 180, 117, 76,
    140, 36, 210, 172, 41, 54, 159, 8, 185, 232, 113, 196, 231, 47, 146, 120,
    51, 65, 28, 144, 254, 221, 93, 189, 194, 139, 112, 43, 71, 109, 184, 209,
};

struct idhash_ret{ char *p; int32 hash; };

#ifdef HAVE_ROTATE

struct idhash_ret idhash(char *p) {
    unsigned char c, d;
    uint32 a;
    unsigned char lo, hi;
    struct idhash_ret ret;

    a = *p;
    c = *++p;
    goto first_test;
    do {
	p += 4;
	ROR(7,a);
	c = p[0];
	a ^= d;
      first_test:
	if (!isalunum(c))
	    goto add0;
	ROR(8,a);
	d = p[1];
	a ^= c;
	if (!isalunum(d))
	    goto add1;
	ROR(8,a);
	c = p[2];
	a ^= d;
	if (!isalunum(c))
	    goto add2;
	ROR(8,a);
	d = p[3];
	a ^= c;
    } while (isalunum(d));
    p += 1;
  add2:
    p += 1;
  add1:
    p += 1;
  add0:
    ROL(1,a);
    c = a;
    c = T[c];
    c ^= a >> 8;
    a >>= 16;
    a ^= T[c] << 8;
    c = a >> 8;
    a ^= T[c];
    ret.p = p;
    ret.hash = a;
    return ret;
}

#else /* !HAVE_ROTATE */

/* Version optimized to cut down rotate instructions, because sparc needs
 * to use two shifts & an (X)OR to do them. aphash() hash value compatibility
 * only for big endian bytesex.
 * Using more rotates, one register can be saved & costumability for little
 * endian aphash() compatibility is available.
 */
struct idhash_ret idhash(char *p) {
    unsigned char c, d;
    uint32 a, b;
    unsigned char lo, hi;
    struct idhash_ret ret;

    b = *p;
    a = 0;
    c = *++p;
    goto first_test;
    do {
	p += 4;
	b <<= 8;
	c = p[0];
	b ^= d;
	ROL(1,a);
	a ^= b;
      first_test:
	if (!isalunum(c))
	    goto add0;
	b <<= 8;
	d = p[1];
	b ^= c;
	if (!isalunum(d))
	    goto add1;
	b <<= 8;
	c = p[2];
	b ^= d;
	if (!isalunum(c))
	    goto add2;
	b <<= 8;
	d = p[3];
	b ^= c;
    } while (isalunum(d));
    p += 1;
  add2:
    p += 1;
  add1:
    p += 1;
  add0:
    ROL(1,a);
    a ^= b;
    c = a;
    c = T[c];
    c ^= a >> 8;
    a >>= 16;
    a ^= T[c] << 8;
    c = a >> 8;
    a ^= T[c];
    ret.p = p;
    ret.hash = a;
    return ret;
}

#endif