Author: Dann Corbit
Date: 13:44:26 01/22/03
Go up one level in this thread
#include <cstdio>
#include <cstring>
#include <climits>
#include <cassert>
typedef unsigned __int64 Bitboard;
static const unsigned char revchr[] = {
0, 128, 64, 192, 32, 160, 96, 224, 16, 144,
80, 208, 48, 176, 112, 240, 8, 136, 72, 200,
40, 168, 104, 232, 24, 152, 88, 216, 56, 184,
120, 248, 4, 132, 68, 196, 36, 164, 100, 228,
20, 148, 84, 212, 52, 180, 116, 244, 12, 140,
76, 204, 44, 172, 108, 236, 28, 156, 92, 220,
60, 188, 124, 252, 2, 130, 66, 194, 34, 162,
98, 226, 18, 146, 82, 210, 50, 178, 114, 242,
10, 138, 74, 202, 42, 170, 106, 234, 26, 154,
90, 218, 58, 186, 122, 250, 6, 134, 70, 198,
38, 166, 102, 230, 22, 150, 86, 214, 54, 182,
118, 246, 14, 142, 78, 206, 46, 174, 110, 238,
30, 158, 94, 222, 62, 190, 126, 254, 1, 129,
65, 193, 33, 161, 97, 225, 17, 145, 81, 209,
49, 177, 113, 241, 9, 137, 73, 201, 41, 169,
105, 233, 25, 153, 89, 217, 57, 185, 121, 249,
5, 133, 69, 197, 37, 165, 101, 229, 21, 149,
85, 213, 53, 181, 117, 245, 13, 141, 77, 205,
45, 173, 109, 237, 29, 157, 93, 221, 61, 189,
125, 253, 3, 131, 67, 195, 35, 163, 99, 227,
19, 147, 83, 211, 51, 179, 115, 243, 11, 139,
75, 203, 43, 171, 107, 235, 27, 155, 91, 219,
59, 187, 123, 251, 7, 135, 71, 199, 39, 167,
103, 231, 23, 151, 87, 215, 55, 183, 119, 247,
15, 143, 79, 207, 47, 175, 111, 239, 31, 159,
95, 223, 63, 191, 127, 255
};
unsigned char swapNibble(unsigned char test)
{
unsigned char loMask = 0x0F;
static const unsigned char rev[] = {0x0, 0x8, 0x4, 0xC, 0x2, 0xA, 0x6, 0xE,
0x1, 0x9, 0x5, 0xD, 0x3, 0xB, 0x7, 0xF};
assert(CHAR_BIT == 8);
return (rev[test & loMask] << 4) | rev[(test >> 4) & loMask];
}
unsigned char revbits_8(unsigned char n)
{
int i = 8;
unsigned char m = -1;
assert(CHAR_BIT == 8);
while (i /= 2)
m ^= m << i, n = n >> i & m | (n & m) << i;
return n;
}
/*
** Separare tasks into basic jobs to be performed.
*/
unsigned char *reverse_64_a(void *v)
{
unsigned char *s = (unsigned char *) v;
unsigned char *last;
unsigned char temp;
size_t lgh = 8;
last = s + lgh;
while (last-- > s) {
temp = revchr[*s];
*s++ = revchr[*last];
*last = temp;
}
return s;
}
/*
** Separare tasks into basic jobs to be performed.
*/
unsigned char *reverse_64_b(void *v)
{
unsigned char *s = (unsigned char *) v;
unsigned char *last;
unsigned char temp;
size_t lgh = 8;
assert(CHAR_BIT == 8);
last = s + lgh;
while (last-- > s) {
temp = swapNibble(*s);
*s++ = swapNibble(*last);
*last = temp;
}
return s;
}
/*
** Separare tasks into basic jobs to be performed.
*/
unsigned char *reverse_64_c(void *v)
{
unsigned char *s = (unsigned char *) v;
unsigned char *last;
unsigned char temp;
size_t lgh = 8;
assert(CHAR_BIT == 8);
last = s + lgh;
while (last-- > s) {
temp = revbits_8(*s);
*s++ = revbits_8(*last);
*last = temp;
}
return s;
}
/*
Some pretty patters for bit reversal of 32 bit integers:
a = ((a << 16) & 0xFFFF0000) | ((a >> 16) & 0x0000FFFF);
a = ((a << 8) & 0xFF00FF00) | ((a >> 8) & 0x00FF00FF);
a = ((a << 4) & 0xF0F0F0F0) | ((a >> 4) & 0x0F0F0F0F);
a = ((a << 2) & 0xCCCCCCCC) | ((a >> 2) & 0x33333333);
a = ((a << 1) & 0xAAAAAAAA) | ((a >> 1) & 0x55555555);
n = ((n >> 1) & 0x55555555) | ((n << 1) & 0xaaaaaaaa);
n = ((n >> 2) & 0x33333333) | ((n << 2) & 0xcccccccc);
n = ((n >> 4) & 0x0f0f0f0f) | ((n << 4) & 0xf0f0f0f0);
n = ((n >> 8) & 0x00ff00ff) | ((n << 8) & 0xff00ff00);
n = ((n >> 16) & 0x0000ffff) | ((n << 16) & 0xffff0000);
*/
Bitboard breverse0(Bitboard n)
{
Bitboard r = 0,
j = 1,
m = n;
while (r = 2 * r + m % 2, j *= 2)
m /= 2;
return r;
}
Bitboard breverse1(Bitboard n)
{
Bitboard r = 0,
j = 1;
while (r = r * 2 | n & 1, j *= 2)
n >>= 1;
return r;
}
Bitboard breverse2(Bitboard n)
{
Bitboard r = 0,
j = 1;
while (r = 2 * r | (n & j) / j, j *= 2);
return r;
}
Bitboard breverse3(Bitboard v)
{
Bitboard r = 0,
q = -1;
while (q) {
r = (r << 1) | (v & 1);
v >>= 1;
q >>= 1;
} return r;
}
Bitboard breverse4(Bitboard v)
{
Bitboard r = 0,
q = -1;
while (q) {
r = (r << 1) | (v & 1);
v >>= 1;
q >>= 1;
} return r;
}
Bitboard breverse5(Bitboard n)
{
int i = 64;
Bitboard m = -1;
while (i /= 2)
m ^= m << i, n = n >> i & m | (n & m) << i;
return n;
}
#include <cstdio>
int main(void)
{
Bitboard a,
b;
b = 0xffffffffffffffffui64;
a = breverse0(b);
if (a != b || a != 0xffffffffffffffffui64)
puts("breverse0 fails.");
a = breverse1(b);
if (a != b || a != 0xffffffffffffffffui64)
puts("breverse1 fails.");
a = breverse2(b);
if (a != b || a != 0xffffffffffffffffui64)
puts("breverse2 fails.");
a = breverse3(b);
if (a != b || a != 0xffffffffffffffffui64)
puts("breverse3 fails.");
a = breverse4(b);
if (a != b || a != 0xffffffffffffffffui64)
puts("breverse4 fails.");
a = breverse5(b);
if (a != b || a != 0xffffffffffffffffui64)
puts("breverse5 fails.");
a = breverse5(b);
if (a != b || a != 0xffffffffffffffffui64)
puts("breverse5 fails.");
reverse_64_a((void *)&b);
if (a != b || a != 0xffffffffffffffffui64)
puts("reverse_64_a fails.");
reverse_64_b((void *)&b);
if (a != b || a != 0xffffffffffffffffui64)
puts("reverse_64_b fails.");
reverse_64_c((void *)&b);
if (a != b || a != 0xffffffffffffffffui64)
puts("reverse_64_c fails.");
b = 0xfafafafafafafafaui64;
a = breverse0(b);
b = breverse0(a);
if (a != breverse0(b) || b != 0xfafafafafafafafaui64)
puts("breverse0 fails.");
b = 0xfafafafafafafafaui64;
a = breverse1(b);
b = breverse1(a);
if (a != breverse1(b) || b != 0xfafafafafafafafaui64)
puts("breverse1 fails.");
b = 0xfafafafafafafafaui64;
a = breverse2(b);
b = breverse2(a);
if (a != breverse2(b) || b != 0xfafafafafafafafaui64)
puts("breverse2 fails.");
b = 0xfafafafafafafafaui64;
a = breverse3(b);
b = breverse3(a);
if (a != breverse3(b) || b != 0xfafafafafafafafaui64)
puts("breverse3 fails.");
b = 0xfafafafafafafafaui64;
a = breverse4(b);
b = breverse4(a);
if (a != breverse4(b) || b != 0xfafafafafafafafaui64)
puts("breverse4 fails.");
a = b = 0xfafafafafafafafaui64;
reverse_64_a((void *)&b);
reverse_64_a((void *)&b);
if (a != b || b != 0xfafafafafafafafaui64)
puts("reverse_64_a fails.");
b = 0xfafafafafafafafaui64;
reverse_64_b((void *)&b);
reverse_64_b((void *)&b);
if (a != b || b != 0xfafafafafafafafaui64)
puts("reverse_64_b fails.");
b = 0xfafafafafafafafaui64;
reverse_64_c((void *)&b);
reverse_64_c((void *)&b);
if (a != b || b != 0xfafafafafafafafaui64)
puts("reverse_64_c fails.");
return 0;
}
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