bit.c

#include <stdarg.h>
#include <string.h>
#include "assert.h"
#include "mem.h"
#include "bit.h"
#define T Bit_T
struct T {
    int length;
    unsigned char *bytes;
    unsigned long *words;
};
#define BPW (8 * sizeof(unsigned long))
/* &(~(BPW - 1)) in case for OVERFLOW
 * If len = 0xfffffff + 1 - BPW, the result without the and operation
 * is nwords(len) = 0
 * */
#define nwords(len) ((((len) + BPW - 1) & (~(BPW - 1))) / BPW)
#define nbytes(len) ((((len) + 8 - 1) & (~(8 - 1))) / 8)
#define __index(n) ((n) >> 3)
#define __offset(n) ((n) % 8)
/* Marco for bit operations.
 * sequal, snull and tnull are the return value when set
 * s and t is equal, s is null and t is null respectively.
 * */
#define setop(sequal, snull, tnull, op) \
    if (s == t) { assert(s); \
         return sequal; } \
    else if (s == NULL) {assert(t); \
         return snull;} \
    else if (t == NULL) { \
         return tnull; } \
    else { \
        int i; T set; \
        assert(s->length == t->length); \
        set = Bit_new(s->length); \
        for (i = nwords(s->length); --i >= 0; ) { \
            set->words[i] = s->words[i] op t->words[i]; \
        } \
        return set; \
    }
unsigned char msbmask[] = {
    0xFF, 0xFE, 0xFC, 0xF8,
    0xF0, 0xE0, 0xC0, 0x80
};
unsigned char lsbmask[] = {
    0x01, 0x03, 0x07, 0x0F,
    0x1F, 0X3F, 0X7F, 0XFF
};

static T copy(T t)
{
    T set;
    assert(t);
    set = Bit_new(t->length);
    if (t->length > 0)
        memcpy(set->bytes, t->bytes, nbytes(t->length));
    return set;
}

T Bit_new(int length)
{
    T set;
    assert(length >= 0);
    NEW(set);
    if (length > 0)
        set->words = CALLOC(nwords(length),
                sizeof(unsigned long));
    else//empty set
        set->words = NULL;
    set->bytes = (unsigned char *)set->words;
    set->length = length;
    return set;
}

void Bit_free(T *set)
{
    assert(set && *set);
    FREE((*set)->words);
    FREE(*set);
}

int Bit_length(T set)
{
    assert(set);
    return set->length;
}

int Bit_count(T set)
{
    int length = 0, n;
    static char count[] = {
  /*0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F */
    0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4};
    assert(set);
    for (n = nbytes(set->length); --n >= 0; ) {
        unsigned char c = set->bytes[n];
        length += count[c & 0xF ] + count[c >> 4];
    }
    return length;
}

int Bit_get(T set, int n)
{
    unsigned int idx = __index(n), offset = __offset(n);
    assert(set);
    assert(n >= 0 && n < set->length);
    return ((set->bytes[n >> 3] >> (n % 8)) & 1);
}

int Bit_put(T set, int n, int bit)
{
    int prev;
    unsigned int idx = __index(n), offset = __offset(n);
    assert(set);
    assert(bit == 0 || bit == 1);
    assert(n >= 0 && n < set->length);
    prev = ((set->bytes[idx] >> (offset)) & 1);
    if (bit == 1)
        set->bytes[idx] |= 1 << (offset);
    else
        set->bytes[idx] &= ~(1<<(offset));
    return prev;
}

void Bit_set(T set, int lo, int hi)
{
    assert(set);
    assert(0 <= lo && hi < set->length);
    assert(lo <= hi);
    if (__index(lo) < __index(hi)) {
        int i;
        unsigned int hi_index = __index(hi);

        set->bytes[__index(lo)] |= msbmask[__offset(lo)];
        for (i = __index(lo) + 1; i < hi_index; ++i) {
            set->bytes[i] = 0xFF;
        }
        set->bytes[hi_index] |= lsbmask[__offset(hi)];
    } else {//same index
        set->bytes[__index(lo)] |=
            (msbmask[__offset(lo)] & lsbmask[__offset(hi)]);
    }
}

void Bit_clear(T set, int lo, int hi)
{
    assert(set);
    assert(0 <= lo && hi < set->length);
    assert(lo <= hi);
    if (__index(lo) < __index(hi)) {
        int i;
        unsigned int hi_index = __index(hi);

        set->bytes[__index(lo)] &= ~msbmask[__offset(lo)];
        for (i = __index(lo) + 1; i < hi_index; ++i) {
            set->bytes[i]  = 0;
        }
        set->bytes[hi_index] &= ~lsbmask[__offset(hi)];
    } else {
        set->bytes[__index(lo)] &=
            ~(msbmask[__offset(lo)] & lsbmask[__offset(hi)]);
    }
}

void Bit_not(T set, int lo, int hi)
{
    assert(set);
    assert(0 <= lo && hi < set->length);
    assert(lo <= hi);
    if (__index(lo) < __index(hi)) {
        int i;
        unsigned int hi_index = __index(hi);

        set->bytes[__index(lo)] ^= msbmask[__offset(lo)];
        for (i = __index(lo) + 1; i < hi_index; ++i) {
            set->bytes[i] ^= 0xFF;
        }
        set->bytes[hi_index] ^= lsbmask[__offset(hi)];
    } else {
        set->bytes[__index(lo)] ^=
            (msbmask[__offset(lo)] & lsbmask[__offset(hi)]);
    }
}

void Bit_map(T set,
        void apply(int n, int bit, void *cl), void *cl) {
    int n;
    int bit;
    assert(set);
    for (n = 0; n < set->length; ++n) {
        bit = ((set->bytes[__index(n)] >> __offset(n)) & 1);
        apply(n, bit, cl);
    }
}

int Bit_eq(T s, T t)
{
    int i;
    assert(s && t);
    assert(s->length == t->length);
    for (i = nwords(s->length); --i >= 0; ) {
        if (s->words[i] != t->words[i])
            return 0;
    }
    return 1;
}

int Bit_leq(T s, T t)
{
    int i;
    assert(s && t);
    assert(s->length == t->length);
    for (i = nwords(s->length); --i >= 0; ) {
        if ((s->words[i] &~ t->words[i]) != 0)
            return 0;
    }
    return 1;
}

int Bit_lt(T s, T t)
{
    int i, lt= 0;
    assert(s && t);
    assert(s->length == t->length);
    for (i = nwords(s->length); --i >= 0; ) {
        if ((s->words[i] &~ t->words[i]) != 0)
            return 0;
        else if (s->words[i] != t->words[i])
            lt |= 1;
    }
    return lt;
}

T Bit_union(T s, T t)
{
    setop(copy(t), copy(s), copy(s), |)
}

T Bit_inter(T s, T t)
{
   setop(copy(t), Bit_new(t->length), Bit_new(s->length), &)
}

T Bit_minus(T s, T t)
{
    setop(Bit_new(s->length), Bit_new(t->length), copy(s), &~)
}

T Bit_diff(T s, T t)
{
    setop(Bit_new(s->length), copy(t), copy(s), ^)
}