#include "bitmap.h"
#include <stdio.h>
#include <stdlib.h>

#ifdef bitmap_64
#define bitmap_type unsigned long long int
#define bitmap_shift 6
#define bitmap_mask 63
#define bitmap_wordlength 64
#define bitmap_fmt "%016llx"
#else // assumed to be 32 bits
#define bitmap_type unsigned int
#define bitmap_shift 5
#define bitmap_mask 31
#define bitmap_wordlength 32
#define bitmap_fmt "%08x"
#endif

// get the types right
#define bitmap_one (bitmap_type)1

// we expect 0 <= n and n < b->bits, but it is not verified

// arch a 8 bit
// bitmap shift 3
// wordlength 8

// n = 10 -> 00001010
// 00000001 -> word = 1
//
// n = 12 ->   00001100
// mask = 7 -> 00000111
//             00000100 = 4
// 00000001 -> word = 1
//
// n = 32 ->    00100000
// mask = 7 ->  00000111
// 00000000
// 00000100 -> word = 4
//
// n = 127 ->      01111111
// mask = 7 ->     00000111
// position = 7 -> 00000111
//

void bitmap_set(bitmap *b, int n) {
  int word = n >> bitmap_shift;   // n / bitmap_wordlength
  int position = n & bitmap_mask; // n % bitmap_wordlength
  b->array[word] |= bitmap_one << position;
}

void bitmap_clear(bitmap *b, int n) {
  int word = n >> bitmap_shift;   // n / bitmap_wordlength
  int position = n & bitmap_mask; // n % bitmap_wordlength
  b->array[word] &= ~(bitmap_one << position);
}

int bitmap_read(bitmap *b, int n) {
  int word = n >> bitmap_shift;   // n / bitmap_wordlength
  int position = n & bitmap_mask; // n % bitmap_wordlength
  return (b->array[word] >> position) & 1;
}

bitmap *bitmap_allocate(int bits) {
  // error-checking should be better :-)
  bitmap *b = malloc(sizeof(bitmap));
  b->bits = bits;
  b->words = (bits + bitmap_wordlength - 1) / bitmap_wordlength;
  // divide, but round up for the ceiling
  b->array = calloc(b->words, sizeof(bitmap_type));
  return b;
}

void bitmap_deallocate(bitmap *b) {
  // error-checking should be better :-)
  free(b->array);
  free(b);
}

void bitmap_print(bitmap *b) {
  for (int i = 0; i < b->words; i++) {
    printf(" " bitmap_fmt, b->array[i]);
  }
  printf("\n");
}