ref: 46f2f47b1405c0f644e6d3dd5b8cdf458c458814
dir: /llt/bitvector.c/
/*
bit vector primitives
todo:
* reverse
* nreverse
(- rotate left/right)
* shl_to
* not
- shr_row, shl_row
These routines are the back end supporting bit matrices. Many operations
on bit matrices are slow (such as accessing or setting a single element!)
but certain operations are privileged and lend themselves to extremely
efficient implementation due to the bit-vector nature of machine integers.
These are:
done:
& | $ ~ copy reverse fill sum prod
todo:
shift trans rowswap
would be nice:
channel interleave
Important note:
Out-of-place functions always assume dest and source have the same amount
of space available.
shr_to, shl_to, not_to, and reverse_to assume source and dest don't overlap
and_to, or_to, and xor_to allow overlap.
*/
#include <stdlib.h>
#include <assert.h>
#include <string.h>
#include "dtypes.h"
#include "bitvector.h"
#ifdef WIN32
#include <malloc.h>
#define alloca _alloca
#endif
// greater than this # of words we use malloc instead of alloca
#define MALLOC_CUTOFF 2000
u_int32_t *bitvector_resize(u_int32_t *b, size_t n, int initzero)
{
u_int32_t *p;
size_t sz = ((n+31)>>5) * 4;
p = realloc(b, sz);
if (p == NULL) return NULL;
if (initzero) memset(p, 0, sz);
return p;
}
u_int32_t *bitvector_new(size_t n, int initzero)
{
return bitvector_resize(NULL, n, initzero);
}
void bitvector_set(u_int32_t *b, u_int32_t n, u_int32_t c)
{
if (c)
b[n>>5] |= (1<<(n&31));
else
b[n>>5] &= ~(1<<(n&31));
}
u_int32_t bitvector_get(u_int32_t *b, u_int32_t n)
{
return b[n>>5] & (1<<(n&31));
}
u_int32_t bitreverse(u_int32_t x)
{
u_int32_t m;
#ifdef __INTEL_COMPILER
x = _bswap(x);
#else
x = (x >> 16) | (x << 16); m = 0xff00ff00;
x = ((x & m) >> 8) | ((x & ~m) << 8);
#endif
m = 0xf0f0f0f0;
x = ((x & m) >> 4) | ((x & ~m) << 4); m = 0xcccccccc;
x = ((x & m) >> 2) | ((x & ~m) << 2); m = 0xaaaaaaaa;
x = ((x & m) >> 1) | ((x & ~m) << 1);
return x;
}
// shift all bits in a long bit vector
// n is # of int32s to consider, s is shift distance
// lowest bit-index is bit 0 of word 0
// TODO: handle boundary case of shift distance >= data size?
void bitvector_shr(u_int32_t *b, size_t n, u_int32_t s)
{
u_int32_t i;
if (s == 0 || n == 0) return;
i = (s>>5);
if (i) {
n -= i;
memmove(b, &b[i], n*4);
memset(&b[n], 0, i*4);
s &= 31;
}
for(i=0; i < n-1; i++) {
b[i] = (b[i]>>s) | (b[i+1]<<(32-s));
}
b[i]>>=s;
}
// out-of-place version, good for re-aligning a strided submatrix to
// linear representation when a copy is needed
// assumes that dest has the same amount of space as source, even if it
// wouldn't have been necessary to hold the shifted bits
void bitvector_shr_to(u_int32_t *dest, u_int32_t *b, size_t n, u_int32_t s)
{
u_int32_t i, j;
if (n == 0) return;
if (s == 0) {
memcpy(dest, b, n*4);
return;
}
j = (s>>5);
if (j) {
n -= j;
memset(&dest[n], 0, j*4);
s &= 31;
b = &b[j];
}
for(i=0; i < n-1; i++) {
dest[i] = (b[i]>>s) | (b[i+1]<<(32-s));
}
dest[i] = b[i]>>s;
}
void bitvector_shl(u_int32_t *b, size_t n, u_int32_t s)
{
u_int32_t i, scrap=0, temp;
if (s == 0 || n == 0) return;
i = (s>>5);
if (i) {
n -= i;
memmove(&b[i], b, n*4);
memset(b, 0, i*4);
s &= 31;
b = &b[i];
}
for(i=0; i < n; i++) {
temp = (b[i]<<s) | scrap;
scrap = b[i]>>(32-s);
b[i] = temp;
}
}
// if dest has more space than source, set scrap to true to keep the
// top bits that would otherwise be shifted out
void bitvector_shl_to(u_int32_t *dest, u_int32_t *b, size_t n, u_int32_t s,
bool_t scrap)
{
u_int32_t i, j, sc=0;
if (n == 0) return;
if (s == 0) {
memcpy(dest, b, n*4);
return;
}
j = (s>>5);
if (j) {
n -= j;
memset(dest, 0, j*4);
s &= 31;
dest = &dest[j];
}
for(i=0; i < n; i++) {
dest[i] = (b[i]<<s) | sc;
sc = b[i]>>(32-s);
}
if (scrap)
dest[i] = sc;
}
// set nbits to c, starting at given bit offset
// assumes offs < 32
void bitvector_fill(u_int32_t *b, u_int32_t offs, u_int32_t c, u_int32_t nbits)
{
index_t i;
u_int32_t nw, tail;
u_int32_t mask;
if (nbits == 0) return;
nw = (offs+nbits+31)>>5;
if (nw == 1) {
mask = (lomask(nbits)<<offs);
if (c) b[0]|=mask; else b[0]&=(~mask);
return;
}
mask = lomask(offs);
if (c) b[0]|=(~mask); else b[0]&=mask;
if (c) mask=ONES32; else mask = 0;
for(i=1; i < nw-1; i++)
b[i] = mask;
tail = (offs+nbits)&31;
if (tail==0) {
b[i] = mask;
}
else {
mask = lomask(tail);
if (c) b[i]|=mask; else b[i]&=(~mask);
}
}
void bitvector_not(u_int32_t *b, u_int32_t offs, u_int32_t nbits)
{
index_t i;
u_int32_t nw, tail;
u_int32_t mask;
if (nbits == 0) return;
nw = (offs+nbits+31)>>5;
if (nw == 1) {
mask = (lomask(nbits)<<offs);
b[0] ^= mask;
return;
}
mask = ~lomask(offs);
b[0]^=mask;
for(i=1; i < nw-1; i++)
b[i] = ~b[i];
tail = (offs+nbits)&31;
if (tail==0) {
b[i] = ~b[i];
}
else {
mask = lomask(tail);
b[i]^=mask;
}
}
// constant-space bit vector copy in a single pass, with arbitrary
// offsets and lengths. to get this right, there are 16 cases to handle!
#define BITVECTOR_COPY_OP(name, OP) \
void bitvector_##name(u_int32_t *dest, u_int32_t doffs, \
u_int32_t *src, u_int32_t soffs, u_int32_t nbits) \
{ \
index_t i; \
u_int32_t s, nw, tail, snw; \
u_int32_t mask, scrap; \
\
if (nbits == 0) return; \
nw = (doffs+nbits+31)>>5; \
\
if (soffs == doffs) { \
if (nw == 1) { \
mask = (lomask(nbits)<<doffs); \
dest[0] = (dest[0] & ~mask) | (OP(src[0]) & mask); \
return; \
} \
mask = ~lomask(doffs); \
dest[0] = (dest[0] & ~mask) | (OP(src[0]) & mask); \
for(i=1; i < nw-1; i++) \
dest[i] = OP(src[i]); \
tail = (doffs+nbits)&31; \
if (tail==0) { dest[i]=src[i]; } else { \
mask = lomask(tail); \
dest[i] = (dest[i] & ~mask) | (OP(src[i]) & mask); } \
return; \
} \
snw = (soffs+nbits+31)>>5; \
if (soffs < doffs) { \
s = doffs-soffs; \
if (nw == 1) { \
mask = (lomask(nbits)<<doffs); \
dest[0] = (dest[0] & ~mask) | ((OP(src[0])<<s) & mask); \
return; \
} \
mask = ~lomask(doffs); \
dest[0] = (dest[0] & ~mask) | ((OP(src[0])<<s) & mask); \
scrap = OP(src[0])>>(32-s); \
for(i=1; i < snw-1; i++) { \
dest[i] = (OP(src[i])<<s) | scrap; \
scrap = OP(src[i])>>(32-s); \
} \
tail = (doffs+nbits)&31; \
if (tail==0) { mask=ONES32; } else { mask = lomask(tail); } \
if (snw == nw) { \
dest[i] = (dest[i] & ~mask) | (((OP(src[i])<<s)|scrap) & mask); \
} \
else /* snw < nw */ { \
if (snw == 1) { \
dest[i] = (dest[i] & ~mask) | \
(((OP(src[i])<<s) | scrap) & mask); \
} \
else { \
dest[i] = (OP(src[i])<<s) | scrap; \
scrap = OP(src[i])>>(32-s); \
i++; \
dest[i] = (dest[i] & ~mask) | (scrap & mask); \
} \
} \
} \
else { \
s = soffs-doffs; \
if (snw == 1) { \
mask = (lomask(nbits)<<doffs); \
dest[0] = (dest[0] & ~mask) | ((OP(src[0])>>s) & mask); \
return; \
} \
if (nw == 1) { \
mask = (lomask(nbits)<<doffs); \
dest[0] = (dest[0] & ~mask) | \
(((OP(src[0])>>s)|(OP(src[1])<<(32-s))) & mask); \
return; \
} \
mask = ~lomask(doffs); \
dest[0] = (dest[0] & ~mask) | \
(((OP(src[0])>>s)|(OP(src[1])<<(32-s))) & mask); \
for(i=1; i < nw-1; i++) { \
dest[i] = (OP(src[i])>>s) | (OP(src[i+1])<<(32-s)); \
} \
tail = (doffs+nbits)&31; \
if (tail==0) { mask=ONES32; } else { mask = lomask(tail); } \
if (snw == nw) { \
dest[i] = (dest[i] & ~mask) | ((OP(src[i])>>s) & mask); \
} \
else /* snw > nw */ { \
dest[i] = (dest[i] & ~mask) | \
(((OP(src[i])>>s)|(OP(src[i+1])<<(32-s))) & mask); \
} \
} \
}
#define BV_COPY(a) (a)
#define BV_NOT(a) (~(a))
BITVECTOR_COPY_OP(copy, BV_COPY)
BITVECTOR_COPY_OP(not_to, BV_NOT)
// right-shift the bits in one logical "row" of a long 2d bit vector
/*
void bitvector_shr_row(u_int32_t *b, u_int32_t offs, size_t nbits, u_int32_t s)
{
}
*/
// copy from source to dest while reversing bit-order
// assumes dest offset == 0
// assumes source and dest don't overlap
// assumes offset < 32
void bitvector_reverse_to(u_int32_t *dest, u_int32_t *src, u_int32_t soffs,
u_int32_t nbits)
{
index_t i;
u_int32_t nw, tail;
if (nbits == 0) return;
nw = (soffs+nbits+31)>>5;
// first, reverse the words while reversing bit order within each word
for(i=0; i < nw/2; i++) {
dest[i] = bitreverse(src[nw-i-1]);
dest[nw-i-1] = bitreverse(src[i]);
}
if (nw&0x1)
dest[i] = bitreverse(src[i]);
tail = (soffs+nbits)&31;
if (tail)
bitvector_shr(dest, nw, 32-tail);
}
void bitvector_reverse(u_int32_t *b, u_int32_t offs, u_int32_t nbits)
{
index_t i;
u_int32_t nw, tail;
u_int32_t *temp;
if (nbits == 0) return;
nw = (offs+nbits+31)>>5;
temp = (nw > MALLOC_CUTOFF) ? malloc(nw*4) : alloca(nw*4);
for(i=0; i < nw/2; i++) {
temp[i] = bitreverse(b[nw-i-1]);
temp[nw-i-1] = bitreverse(b[i]);
}
if (nw&0x1)
temp[i] = bitreverse(b[i]);
tail = (offs+nbits)&31;
bitvector_copy(b, offs, temp, (32-tail)&31, nbits);
if (nw > MALLOC_CUTOFF) free(temp);
}
u_int32_t bitvector_count(u_int32_t *b, u_int32_t offs, u_int32_t nbits)
{
index_t i;
u_int32_t nw, tail;
u_int32_t ans;
if (nbits == 0) return 0;
nw = (offs+nbits+31)>>5;
if (nw == 1) {
return count_bits(b[0] & (lomask(nbits)<<offs));
}
ans = count_bits(b[0]>>offs); // first end cap
for(i=1; i < nw-1; i++) {
/* popcnt can be computed branch-free, so these special cases
probably don't help much */
/*
v = b[i];
if (v == 0)
continue;
if (v == ONES32)
ans += 32;
else
*/
ans += count_bits(b[i]);
}
tail = (offs+nbits)&31;
ans += count_bits(b[i]&(tail>0?lomask(tail):ONES32)); // last end cap
return ans;
}
u_int32_t bitvector_any0(u_int32_t *b, u_int32_t offs, u_int32_t nbits)
{
index_t i;
u_int32_t nw, tail;
u_int32_t mask;
if (nbits == 0) return 0;
nw = (offs+nbits+31)>>5;
if (nw == 1) {
mask = (lomask(nbits)<<offs);
if ((b[0] & mask) != mask) return 1;
return 0;
}
mask = ~lomask(offs);
if ((b[0] & mask) != mask) return 1;
for(i=1; i < nw-1; i++) {
if (b[i] != ONES32) return 1;
}
tail = (offs+nbits)&31;
if (tail==0) {
if (b[i] != ONES32) return 1;
}
else {
mask = lomask(tail);
if ((b[i] & mask) != mask) return 1;
}
return 0;
}
u_int32_t bitvector_any1(u_int32_t *b, u_int32_t offs, u_int32_t nbits)
{
index_t i;
u_int32_t nw, tail;
u_int32_t mask;
if (nbits == 0) return 0;
nw = (offs+nbits+31)>>5;
if (nw == 1) {
mask = (lomask(nbits)<<offs);
if ((b[0] & mask) != 0) return 1;
return 0;
}
mask = ~lomask(offs);
if ((b[0] & mask) != 0) return 1;
for(i=1; i < nw-1; i++) {
if (b[i] != 0) return 1;
}
tail = (offs+nbits)&31;
if (tail==0) {
if (b[i] != 0) return 1;
}
else {
mask = lomask(tail);
if ((b[i] & mask) != 0) return 1;
}
return 0;
}
static void adjust_offset_to(u_int32_t *dest, u_int32_t *src, u_int32_t nw,
u_int32_t soffs, u_int32_t newoffs)
{
if (newoffs > soffs)
bitvector_shl_to(dest, src, nw, newoffs-soffs, true);
else
bitvector_shr_to(dest, src, nw, soffs-newoffs);
}
#define BITVECTOR_BINARY_OP_TO(opname, OP) \
void bitvector_##opname##_to(u_int32_t *dest, u_int32_t doffs, \
u_int32_t *a, u_int32_t aoffs, \
u_int32_t *b, u_int32_t boffs, u_int32_t nbits) \
{ \
u_int32_t nw = (doffs+nbits+31)>>5; \
u_int32_t *temp = nw>MALLOC_CUTOFF ? malloc((nw+1)*4) : alloca((nw+1)*4);\
u_int32_t i, anw, bnw; \
if (aoffs == boffs) { \
anw = (aoffs+nbits+31)>>5; \
} \
else if (aoffs == doffs) { \
bnw = (boffs+nbits+31)>>5; \
adjust_offset_to(temp, b, bnw, boffs, aoffs); \
b = temp; anw = nw; \
} \
else { \
anw = (aoffs+nbits+31)>>5; \
bnw = (boffs+nbits+31)>>5; \
adjust_offset_to(temp, a, anw, aoffs, boffs); \
a = temp; aoffs = boffs; anw = bnw; \
} \
for(i=0; i < anw; i++) temp[i] = OP(a[i], b[i]); \
bitvector_copy(dest, doffs, temp, aoffs, nbits); \
if (nw>MALLOC_CUTOFF) free(temp); \
}
#define BV_AND(a,b) ((a)&(b))
#define BV_OR(a,b) ((a)|(b))
#define BV_XOR(a,b) ((a)^(b))
BITVECTOR_BINARY_OP_TO(and, BV_AND)
BITVECTOR_BINARY_OP_TO(or, BV_OR)
BITVECTOR_BINARY_OP_TO(xor, BV_XOR)